Changes in the List

The nine primates lost from the 2004–2006 list, were substituted by six which had never before been include amongst the World's 25 Most Endangered, and three which had been listed in previous years. The reasons why species were removed from the list differ. In the case of the Eastern gorillas and the Neotropical species considerable attention is being given to their plight and conservation measures—research, distribution and status surveys, evaluation and mitigation measures for threats, creation and management of protected areas, environmental awareness and community programs—are underway to the extent that some guarantees are evident for their survival in the short- to mid-term. There are three species which have coincident ranges in West Africa (Côte d'Ivoire and Ghana), and each jockeys for the position of the flagship—Miss Waldron's red colobus, the white-naped mangabey and the roloway guenon. In 2004–2006, the white-naped managabey was the one, in 2006–2008 it was the turn of the roloway guenon. They both call for urgent measures to protect their remaining forests and populations. Miss Waldron's red colobus was brought back onto the list (previously 2002–2004). Its extinction was even reported in 2000, but hope lingers on with rare signs and reports that there are some still living. Repeated efforts since 2000, however, have still failed to find any in the wild. It is significant that there are three red colobus monkeys on the 2006–2008 list—there could (should) undoubtedly be more. Distribution and population surveys and genetic studies are providing new information to help us clarify the complex taxonomy and poorly known ranges of the red colobus monkeys, and it is becoming increasingly evident that many are in very serious difficulties. The red colobus monkeys are uncommonly susceptible to hunting and forest loss, and listing three of them here signals the need for further research and urgent conservation measures for the entire genus.

Table 2.

The distribution by country of the the World's 25 Most Endangered Primates 2006–2008.

Table 3.

Primates on the 2004–2006 list of the world's 25 most endangered primates that were removed from the 2006–2008 list.

Table 4.

The six primates appearing on the list of the world's 25 most endangered primates for the first time, 2006–2008.

In the case of the Mt. Rungwe galago, its listing in 2004 resulted in distribution and status surveys that have indicated that it is less threatened than the Rondo dwarf galago to which its place was given. The listing of Perrier's sifaka was given over to the Sahamalaza Peninsula sportive lemur, serving as a representative of the possible and usually probable plight of many of the numerous lemurs described for the first time over the last two years—known only from single localities or desperately small forest patches. The kipunji, a dramatic find in Tanzania in 2003, is known from just two localities. Their populations are small and fragmented, and the place of this mangabey on the 2006 list was ceded by the Sanje River mangabey, which has been receiving increasing and promising attention for the protection of its populations and forests.

Many of the Asian langurs are now severely threatened, not only from subsistence hunting and habitat loss, but also from hunting for body parts and tissues to satisfy the insatiable demands of the Asian peoples for exotic dishes and concoctions of wild animals, for amulets, remedies and aphrodisiacs. Six of the Asian colobines are on this 2006–2008 list, and Miller's grizzled surili was an ephemeral representative of so many others which should also be highlighted. It is significant that 11 of the 25 Most Endangered Primates are from Asia. A list of the most threatened primates in Asia could easily reach 50, all as threatened as any on this list of the World's 25 Most Endangered.

Table 5 shows the four lists produced to date. Eight species have remained on the list since 2000: the silky sifaka (Propithecus candidus), four Asian colobines—Delacour's langur (Trachypithecus delacouri), the golden-headed or Cat Ba langur (T. p. poliocephalus), the grey-shanked douc (Pygathrix cinerea), and the Tonkin snub-nosed monkey (Rhinopithecus avunculus)—the Hainan gibbon (Nomascus hainanus), the Cross River gorilla (Gorilla gorilla diehli), and the Sumatran orangutan (Pongo abelii).

Greater Bamboo Lemur

Prolemur simus (Gray, 1871)

Madagascar

(2002, 2004, 2006)

Formerly in the genus Hapalemur, Groves (2001) placed the greater bamboo lemur in the genus Prolemur based on a suite of distinctive dental and chromosomal characteristics (Vuillaume-Randriamanantena et al. 1985; Macedonia and Stanger 1994; Stanger-Hall 1997). As its common name implies, the greater bamboo lemur is the largest of Madagascar's bamboo-eating lemurs (Albrecht et al. 1990). Genetic studies further support its separation from the other bamboo lemurs and suggest that Hapalemur may, in fact, be more closely related to the genus Lemur (Rumpler et al. 1989; Macedonia and Stanger 1994; Stanger-Hall 1997). Historical records (Schwarz 1931) and sub-fossil remains confirm that it was once widespread throughout the island (Godfrey and Vuillaume-Randriamanantena 1986; Wilson et al. 1988; Godfrey et al. 1999). Documented populations are very patchily distributed and restricted to the south-central portion of the country's eastern rain forests, including those of Kianjavato, Ranomafana and Andringitra National Parks (and the corridor between them), Evendra (near Ivato, southeast of Andringitra), Karianga (near Vondrozo), and possibly the forest fragments south of Ifanadiana (Meier and Rumpler 1987; Wright et al. 1987; Sterling and Ramaroson 1996; Goodman et al. 2001b; Irwin et al. 2005). Recent unpublished reports also indicate its presence in the forests of Karianga, northwest of Manombo (E. E. Louis Jr. pers. comm.) and north up to the region of Moramanga (Dolch et al. 2004; Rakotosamimanana et al. 2004). Shoots, young and mature leaves, and pith of the bamboo Cathariostachys madagascariensis can account for as much as 95% of the diet (Tan 1999, 2000). Other food items include flowers of the traveler's palm (Ravenala madagascariensis), and fruits of Artocarpus integrifolia, Ficus spp. and Dypsis spp., and leaves of Pennisetum clandestinum (Meier and Rumpler 1987). Observations of animals in the wild and captivity suggest that P. simus is cathemeral (Santini-Palka 1994; Tan 1999, 2000). They live in polygynous groups of seven to 11 animals occupying home ranges of 60 ha or more (Sterling and Ramaroson 1996; Tan 1999, 2000). The greater bamboo lemur is threatened by slash-and-burn agriculture, illegal logging, the cutting of bamboo, and hunting with slingshots (Meier 1987; Meier and Rumpler 1987). It has vanished from most of its former range and only a few relatively small populations have been documented thus far in the southeast. Hunting and habitat destruction are the presumed causes. It occurs in the national parks of Ranomafana and Andringitra (although limited by suitable microhabitat within these protected areas). The population in Ranomafana National Park is estimated at no more than 250 adult individuals (P. C. Wright pers. comm.). Opportunities exist to extend protection to lemur populations in neighboring forests, as well as to develop a fairly long corridor of protected forests between Ranomafana and Andringitra, within which it is presumed other greater bamboo lemur populations will be found.

Jörg U. Ganzhorn & Steig Johnson

White-collared Lemur

Eulemur albocollaris (Rumpler, 1975)

Madagascar

(2004, 2006)

The white-collared lemur was formerly classed as a subspecies of Eulemur fulvus (Tattersall 1982; Mittermeier et al. 1994; Pastorini et al. 2000). Recent cytogenetic and molecular genetic analyses support full species status for Eulemur albocollaris (Djletati et al. 1997; Wyner et al. 1999), despite natural hybridization between this taxon and Eulemur f. rufus (Sterling and Ramarason 1996; Johnson and Wyner 2000; Wyner et al. 2002). The white-collared lemur has one of the most restricted ranges of any Eulemur species, occurring only in southeastern Madagascar in a thin strip of rain forest that runs from just north of the Manampatrana River south to the Mananara River (Petter and Petter-Rousseaux 1979; Tattersall 1982; Irwin et al. 2005). The hybrid zone with E. f. rufus is centered on the headwaters region of the Manampatrana River in Andringitra National Park, extending south to the vicinity of Karianga and north to near Ankarimbelo (Irwin et al. 2005; S. Johnson unpublished data), and encompassing an area of up to 50% of the range of “pure” E. albocollaris. Two isolated populations also occur in the coastal fragments of Manombo Special Reserve and Mahabo Forest near Farafangana. Recent analyses combining ground surveys and Landsat imagery indicate that the total habitat remaining within this species' range is approximately 700 km2, with an estimated remaining population of 7,265 ± 2,268 individuals (Irwin et al. 2005). Information regarding the natural history of this lemur comes largely from recent studies conducted at Vevembe Forest, with new long-term studies underway at Manombo and Mahabo.

Table 5.

The four lists of the World's 25 Most Endangered Primates produced to date. The eight species shaded are those which have remained on the list since 2000.

The white-collared lemur has a largely frugivorous diet, supplemented with flowers, leaves, and fungi; Pandanus spp. flowers are an especially important food late in the dry season (Johnson 2002). The species is cathemeral (active both day and night) throughout the year. Social groups tend to be multi-male/multi-female and regularly exhibit fission-fusion. Selective logging, hunting and the conversion of its habitat to agricultural land are the greatest threats to the survival of the white-collared lemur. It is found in only two protected areas, the Andringitra National Park and Manombo Special Reserve, but the Andringitra population appears to be largely composed of hybrids (CBSG 2002; Wyner et al. 2002). Recent research has identified populations in unprotected forests (Vevembe, for example) that could be added to existing parks and reserves (Johnson and Overdorff 1999). The Missouri Botanical Garden is also presently active in managing and upgrading the protected status of the littoral forest of Mahabo. It should be noted that a possible third Eulemur species, E. cinereiceps, has been suggested to occur within or near the coastal portion of the range of E. albocollaris based on variant museum specimens and captive individuals (Groves 2001; Mittermeier et al. 2006). However, the weight of current evidence suggests this taxon is either synonymous with E. albocollaris or extinct. All surveyed remaining habitats appear to contain either E. albocollaris (Manombo and Mahabo, south of Farafangana) or are too small and/or disturbed to support Eulemur (for example, Analalava and Sakanany, north of Farafangana); however, exhaustive ground surveys and genetic sampling should be conducted in the region to confirm these findings.

Steig Johnson & William R. Konstant

Silky Sifaka

Propithecus candidus Grandidier, 1871

Madagascar

(2000, 2002, 2004, 2006)

Propithecus candidus is a large, white, rainforest sifaka found only within a small section of northeastern Madagascar. Surveys for these highly social diurnal indriids suggest that they are patchily distributed and occur at low densities within just a few protected areas: Marojejy National Park, Anjanaharibe-Sud Special Reserve, and (very rarely) the Anjanaharibe and Manandriana portions of Makira Protected Area north of the Antainambalana River. They have been observed primarily in undisturbed forest (except for the Betaolana Corridor) between 700 m and 1,875 m above sea level (Tattersall 1982; Duckworth et al. 1995; Schmid and Smolker 1998; Sterling and McFadden 2000; Goodman et al. 2003; Rakotondratsimba et al. 2007). The behavior and ecology of this species is known mainly from a short study (Kelley and Mayor 2002) and a 14.5-month study at Marojejy National Park (Patel et al. 2005; Patel 2005, 2006, 2007, submitted).

The silky sifaka°s diet is highly folivorous, including mature and young leaves. They also eat fruit, flowers, seeds, bark, soil, and roots. Silky sifakas are the flagship species of a newly proposed World Heritage Site (Marojejy National Park) and are the species that most tourists come to view. Their social structure appears variable (pair-living and polygynandrous), with group sizes ranging from 2 to 9 individuals. Home ranges can exceed 40 ha (Patel 2006). They inhabit several types of elevation-specific habitats including primary montane rainforest, sclerophyllous forest, and even low ericoid bush at their highest elevations (Goodman 2000). Their primary conservation threat appears to be hunting (Patel et al. 2005). Habitat disturbance, such as slash-and-burn agriculture (‘tavy’), logging of precious woods (for example, rosewood) and fuel-wood, also occurs within and adjacent to the protected areas where they are found (Patel submitted). The remaining population may be as low as a few hundred individuals and is unlikely to be larger than a few thousand (Mittermeier et al. 2006).

Erik R. Patel, David Meyers & Frank Hawkins

Sahamalaza Sportive Lemur

Lepilemur sahamalazensis Andriaholinirina et al., 2006

Madagascar

(2006)

The Sahamalaza sportive lemur (Lepilemur sahamalazensis) is one of the numerous lemurs recently described based on genetic and morphometric data (Andriaholinirina et al. 2006). Although the range of this medium-sized, nocturnal primate is not precisely known, it is thought to be strictly limited to the Sahamalaza Peninsula in northwestern Madagascar. The peninsula is part of a transition zone between the Sambirano region in the north and the western dry deciduous forest region in the south. The forests in this area contain a mixture of plant species typical of dry forest and some typical of the Sambirano domain (Birkinshaw 2004). Lepilemur sahamalazensis depends on these semi-humid forests, of which only a few fragments now remain. Very little is known about the ecology and behavior of the Sahamalaza sportive lemur. During preliminary night observations, individuals were mostly encountered alone or in groups of two. During the daytime, they were found sleeping in tree holes. This suggests that they have a social structure typical for the Lepilemur genus, i.e., pair-living animals defending exclusive territories. Encounter rate is high in the forest of Ankarafa (Olivieri et al. 2005). This could be due to recent loss of habitat, forcing all animals to concentrate in the few remaining forest fragments.

Total numbers are unknown but, taking into account the limited distribution of L. sahamalazensis and the small extent of remaining forest cover, they are probably in their low thousands. The species is present in the recently established Parc National de Sahamalaza — Iles Radama (Aire Protégée Terrestre, Marine et Côtière) which is part of the Malagasy protected area network managed through the Association Nationale pour la Gestion des Aires Protégées (ANGAP). The Sahamalaza Peninsula is also a UNESCO Biosphere Reserve (declared in 2001). Although the protected area probably covers the entire distribution of L. sahamalazensis, forest-clearing for agriculture, and timber-cutting for charcoal and construction continue at an alarming rate. Additionally, as is true for all sportive lemurs, it suffers from a high hunting pressure. These animals are easy and defenceless prey for hunters that find their sleeping sites during the day and cut the tree down or climb it to fetch them. Furthermore, traps are laid, harming not only L. sahamalazensis but also the Critically Endangered blue-eyed black lemur (Eulemur macaco flavifrons,) which has a similar distribution.

The combination of a very limited range containing only little and rapidly decreasing suitable habitat with a high hunting pressure makes this species especially vulnerable. A consortium of the Association Européenne pour l'Etude et la Conservation des Lémuriens (AEECL), the Wildlife Conservation Society (WCS), ANGAP, and the local communities is currently establishing structures to ensure better protection of the few remaining forest fragments in the park (Schwitzer et al. 2006). Simultaneously, studies are under way to determine the exact distribution of L. sahamalazensis as well as the density and size of the remaining population.

Gillian L. Olivieri, Christoph Schwitzer, Nora Schwitzer, Mathias Craul & Guy H. Randriatahina

Rondo Dwarf Galago

Galagoides rondoensis (Honess in Kingdon, 1997)

Tanzania

(2006)

Weighing approximately 60 g, this is the smallest of all galago species (Honess 1996b). It is distinct from other dwarf galagos in its diminutive size, a bottle-brush-shaped tail, its reproductive anatomy, and its distinctive “double unit rolling call” (Bearder et al. 1995; Honess 1996a, 1996b). Current knowledge indicates that this species occurs in two distinct areas, one in southwest Tanzania near the coastal towns of Lindi and Mtwara, the other approximately 400 km further north, above the Rufiji River, in pockets of forest around Dar es Salaam. One further population occurs in Sadaani National Park, approximately 100 km north of Dar es Salaam. Rondo dwarf galagos have a mixed diet of insects and fruit, often feed close to the ground, and move by vertical clinging and leaping in the shrubby understorey. They build daytime sleeping nests, which are often in the canopy (Bearder et al. 2003). As with many small primates, G. rondoensis is probably subject to predation from owls and other nocturnal predators. Among these, genets, palm civets and snakes are known to invoke intense episodes of alarm calling (Honess 1996b).

The IUCN Red List gives G. rondoensis as Endangered B2ab(i–v) (IUCN 2006). It has an extremely limited and fragmented range in a number of remnant patches of Eastern African Coastal Dry Forest (sensu Burgess and Clarke 2000, p. 18) in Tanzania, namely those at Zaraninge forest (06°08′S, 38°38′E) in Sadaani National Park (Perkin 2000), Pande Game Reserve (GR) (06°42′S, 39°05′E), Pugu/Kazimzumbwi (06°54′S, 39°05′E) (Perkin 2003, 2004), Rondo (10°08′S, 39°12′E), Litipo (10°02′S, 39°29′E) and Ziwani (10°20′S, 40°18′E) forest reserves (FR) (Honess 1996b; Honess and Bearder 1996). Specimens of G. rondoensis, originally described as Galagoides demidovii phasma, were collected by Ionides from Rondo Plateau in 1955, and Lumsden from Nambunga, near Kitangari, (approximately 10°40′S, 39°25′E) on the Makonde Plateau in Newala District in 1953. Doubts surround the persistence of this species on the Makonde Plateau, which has been extensively cleared for agriculture. Surveys there in 1992 failed to detect any extant populations (Honess 1996b).

No detailed surveys have been conducted to assess population sizes of G. rondoensis. Limited distribution surveys have been conducted, however, in the southern (Honess 1996b) and northern coastal forests (27 surveyed) of Tanzania and coastal Kenya (seven surveyed) (Perkin 2000, 2003, 2004). Absolute population sizes remain undetermined but recent surveys have provided estimates of density (3–6/ha at Pande Game Reserve [Perkin 2003] and 8/ha at Pugu Forest Reserve [Perkin 2004]) and relative abundance from encounter rate (3–10/hr at Pande Game Reserve and Pugu/Kazimzumbwi Forest Reserve [Perkin 2003, 2004] and 3.94/hr at Rondo Forest Reserve [Honess 1996b]). There is a clear and urgent need for further surveys to determine population sizes in these dwindling forest patches. The total area of forest in which G. rondoensis is currently known to occur does not exceed 92.6 km² (Pande GR: 2.4 km², Rondo FR: 25 km², Ziwani FR: 7.7 km², Pugu/Kazimzumbwi FR: 33.5 km², Litipo FR: 4 km² and Zaraninge forest: 20 km² [Minimum area data source: Burgess and Clarke 2000; Doggart 2003]). The major threat facing this species is loss of habitat. All sites are subject to some level of agricultural encroachment, charcoal manufacture and/or logging. All sites, except Pande GR and Zaraninge forest, are national or local authority forest reserves and as such nominally, but in practice minimally, protected. Given current trends in charcoal production for nearby Dar es Salaam, the forest reserves of Pugu and Kazimzumbwi will disappear over the next 10–15 years (Ahrends 2005). Pande, as a Game Reserve, is perhaps more secure, and Zareninge forest, being in a National Park, is the most protected part of the range of G. rondoensis. Conservation action is urgently needed, and more research is required to determine the continuing rate of habitat loss at these sites and to survey new areas for remnant populations.

Across its known range, the Rondo galago can be found sympatric with a number of other galagos, including two much larger species in the genus Otolemur: Garnett's galago, O. garnettii, and the thick-tailed galago, O. crassicaudatus. The Rondo galago is sympatric with the Zanzibar galago, Galagoides zanzibaricus, in the northern parts of its range (for example, in Zaraninge forest, Pugu/Kazimzumbwi FR and Pande GR). G. zanzibaricus is classified as Lower Risk (Near Threatened) in the 2006 IUCN Red List (IUCN 2006) due to threats to its habitat. In the southern parts of its range (for example, at Rondo, Litipo and Ziwani FRs), the Rondo galago is sympatric with Grant's galago, Galagoides granti, which is listed as Data Deficient (IUCN 2006). The Mountain dwarf galago, Galagoides orinus, ranked as Data Deficient (IUCN 2006), is restricted to areas of sub-montane and montane forest in the Eastern Arc Mountains further inland in Tanzania. As such G. orinus also has a very restricted range, although areas of its preferred habitat are believed to be at less risk of degradation because they are relatively inaccessible.

Paul E. Honess, Andrew Perkin & Simon K. Bearder

Roloway Guenon

Cercopithecus diana roloway (Schreber, 1774)

Ghana and Côte d'Ivoire

(2002, 2006)

There are two subspecies of Cercopithecus diana, both highly attractive, arboreal monkeys that inhabit the Upper Guinean forests of West Africa (Grubb et al. 2003). The Roloway subspecies is distinguished by its broad white brow line, long white beard and yellow thighs. Groves (2001) considers the two subspecies to be sufficiently distinct to be regarded as full species. Of the two forms, the Roloway, which is known from Ghana and eastern Côte d'Ivoire, is more seriously threatened with extinction. In fact, along with the white-naped mangabey (Cercocebus atys lunulatus) and Miss Waldron's red colobus (Procolobus badius waldroni), it is among the three most endangered monkeys of the Upper Guinea forest block and a target species of the relentless bushmeat trade (Oates 1996).

As primatologists search the tropical forests of Ghana and Côte d'Ivoire for evidence of living red colobus, they are also documenting the continued decline of both the Roloway guenon and white-naped mangabey, which seem to be found in and to be absent from many of the same forests (Struhsaker and Oates 1995; Oates et al. 1996/1997; McGraw 1998a; Kone 2004; Oates 2006). In Ghana, Roloway guenons have been steadily extirpated from both unprotected and protected areas (for example, Bia National Park) and the monkey is nearing extinction in that country if it has not disappeared already. Very recent surveys failed to confirm the presence of Roloways in four reserves in western Ghana including one—Krokosua Hills Forest Reserve—believed to harbor the monkey only several years earlier (Magnuson 2003; Oates 2006). It is possible that Ankasa Resource Reserve still contains a few Roloway individuals (Magnuson 2003), but in 2006 a wildlife guard reported to J. Oates (unpublished) that he had not seen the monkey for several years. A thorough new survey of Ankasa, and of the Dadieso Forest Reserve (where the monkey was also reported in the recent past) should be a high priority.

In neighboring Côte d'Ivoire, the Roloway guenon is not known from any protected areas and the monkey's status is equally dire. Surveys made ten years ago documented Roloways in two forests: the Yaya Forest Reserve and wet forest adjacent to the Ehy Lagoon (McGraw 1998b, 2005). Field surveys made in 2004 failed to document Roloways at additional sites in southern Côte d'Ivoire (Kone and Akpatou 2005) although hunters indicate that Roloways are present in small numbers in the Parc National des Iles Ehotilé (Kone and Akpatou 2005). Intensive and systematic primate inventories must be carried out at both Ehotilé and Ehy.

W. Scott McGraw & John F. Oates

Pennant's Red Colobus

Procolobus pennantii pennantii (Waterhouse, 1838)

Bioko Island, Equatorial Guinea

(2004, 2006)

The endangered Pennant's red colobus monkey Procolobus pennantii (Waterhouse, 1838) is presently regarded by the IUCN/SSC Primate Specialist Group as comprised of four subspecies, but their relationships within P. pennantii, and with other taxa of red colobus, need clarification (Groves 2001; Grubb et al. 2003). Future research may reveal that these four “subspecies” are better referred to as full species. P. pennantii takes its name from the form restricted to Bioko Island, Equatorial Guinea, P. pennantii pennantii. This endangered subspecies probably has the most restricted range of all of Bioko's 11 primates, and is now found only in a small part of the southwest of the island, within the Gran Caldera and Southern Highlands Scientific Reserve (51,000 ha). P. p. pennantii is threatened by bushmeat hunting, most notably since the early 1980's when a commercial bushmeat market appeared in the town of Malabo (Butynski and Koster 1994). Hearn et al. (2006) estimated numbers killed for bushmeat at 550 and 350 in the years 2004 and 2005, respectively, and a decline of more than 40% in the population over the 20 years from 1986 to 2006. The average price paid in the Malabo market for an adult P. pennantii in 2006 was about US$42. This is well over twice as much as the cost of the readily available, high quality, whole chicken and beef at the same market. Similar high prices are paid on Bioko for all seven species of monkeys and for both species of duikers. Bushmeat on Bioko is, obviously, now a ‘luxury food’ (Hearn et al. 2006). Probably all of the P. pennantii killed on Bioko at this time are coming from within the Gran Caldera and Southern Highlands Scientific Reserve, but small numbers may persist in the most remote and rugged parts of Bioko's other protected area, the Pico Basile National Park (330 km2). The continued high flow of primates, duikers and other wildlife into the Malabo bushmeat market indicates that neither ‘protected area’ is receiving adequate protection from the government of Equatorial Guinea.

The other three subspecies are: the critically endangered Bouvier's red colobus P. p. bouvieri (Rochebrune, 1887) of east-central Republic of Congo; the endangered Niger Delta red colobus P. p. epieni Grubb and Powell, 1999, of Nigeria; and the endangered Preuss's red colobus P. p. preussi (Matschie, 1900) of southeastern Nigeria and western Cameroon (Oates 1994, 2000; Struhsaker 2005). P. p. pennantii and P. p. preussi are particularly distinct taxa in terms of their vocalizations, while the vocal repertoire of P. p. epieni most closely resembles those of the red colobus in central and eastern Africa (T. T. Struhsaker unpublished data).

To the northwest of the P. pennantii complex of subspecies occurs the critically endangered Miss Waldron's red colobus P. badius waldroni (Hayman, 1936) of southwestern Ghana and southeastern Côte d'Ivoire (Struhsaker 1999; Oates et al. 2000; Groves 2001; Grubb et al. 2003). All five of these subspecies are today close to extinction, with very restricted ranges and small numbers as a result of intensive hunting and extensive habitat degradation and loss (Wolfheim 1983; Oates 1994, 1996; Oates et al. 2000; Struhsaker 2005; Hearn et al. 2006). Neither P. p. bouvieri nor P. b. waldroni have been observed alive by scientists for at least 25 years, raising concerns that they may be extinct (see profile for Miss Waldron's red colobus in this report).

The red colobus monkeys of West Africa and west Central Africa are probably more threatened than any other taxonomic group of primates in Africa. This is partly due to the fact that red colobus are especially sensitive to habitat degradation and vulnerable to hunters (Oates 1996; Oates et al. 2000; Waltert et al. 2002; Struhsaker 2005). None of the few protected areas in which any of these five subspecies of red colobus occur is well protected (e.g., McGraw 1998). Of very high priority for the conservation of primate biodiversity in Africa is the need to (1) immediately undertake field surveys to determine the current distributions and abundance of these five subspecies of red colobus, and, at the same time, (2) rigorously protect all of those populations that are known to exist.

Providing adequate protection to viable populations of these five subspecies of red colobus would greatly assist the conservation of numerous sympatric threatened taxa. Among primates, these include: the mainland Preuss's monkey Cercopithecus preussi preussi; Bioko Preuss's monkey C. p. insularis; Bioko red-eared monkey C. erythrotis erythrotis; golden-bellied crowned monkey C. pogonias pogonias; Roloway monkey C. diana roloway; Bioko greater white-nosed monkey C. nictitans martini; Bioko black colobus Colobus satanas satanas; white-naped mangabey Cercocebus atys lunulatus; mainland drill Mandrillus leucophaeus leucophaeus; Bioko drill M. l. poensis; western chimpanzee Pan troglodytes verus; and Nigeria chimpanzee P. t. vellerosus.

If a concerted effort is to be made to save all of the diversity present within the red colobus, then the major international conservation NGOs will need to focus their efforts on this taxonomic group and work closely with national conservation NGOs and national protected area authorities. For P. p. bouvieri and P. b. waldroni, however, it may already be too late.

Thomas M. Butynski, John F. Oates, W. Scott McGraw & Thomas T. Struhsaker

Tana River Red Colobus

Procolobus rufomitratus Peters, 1879

Kenya

(2002, 2004, 2006)

The gallery forests of the lower Tana River, Kenya, are home to two Critically Endangered primates, the Tana River red colobus and the Tana River mangabey, Cercocebus galeritus Peters, 1879. Along with six other primates, they inhabit small patches of forest along a 60-km stretch of river, from Nkanjonja to Mitapani (01°55′S, 40°05′E). While the other species of monkeys have larger geographic distributions, the red colobus and mangabey are restricted to these forests.

The two species receive some protection in approximately 13 km² of forest within the 169-km² Tana River Primate National Reserve (TRPNR). Forest loss to agriculture, however, has increased greatly over the last 15 years or so, and it is estimated that about 50% of the original vegetation has been lost. In addition, local people continue to depend on the remaining forest for materials to build homes and canoes, for the collection of wild honey and other non-timber products. Further losses of habitat have occurred due to the failure of the Tana Delta Irrigation Project's (TDIP) rice-growing scheme (under the administration of the Tana and Athi Rivers Development Authority and financing from Japan International Cooperation Agency) to protect forest patches on their land. A consequence of this continuing loss and degradation of forest is that the populations of the red colobus and the mangabey are believed to have each declined to fewer than 1,000 individuals. Ominously, new threats are now on the horizon with a proposal to establish a large sugar cane plantation in the TDIP area. This new plantation is likely to result in a large influx of people and an increase in the demand for forest resources.

A 5-year World Bank/GEF project begun in 1996 to enhance conservation and protection of the primates and forests was terminated prematurely due to poor project management. This left responsibility for the conservation and protection of the Tana River's remaining forests and primates entirely to the Kenya Wildlife Service (KWS). Nevertheless, there are some positive developments. In 2005, more than 250 families who farmed within the TRPNR were voluntarily relocated to Kipini (about 90 km away) by the KWS. In addition, there appears to be an increasing concern for forest and biodiversity conservation among the people of the area and a major focus of action among community-based organizations is likely to be reforestation and ecotourism activities over the next few decades. However, given the current level of threat for these primates, it will take many years before there is sufficient change on the ground to reverse the long-standing decline of the populations of the Tana River red colobus and the Tana River mangabey.

David N. M. Mbora & Thomas M. Butynski

Miss Waldron's Red Colobus

Procolobus badius waldroni (Hayman, 1936)

Ghana and Côte d'Ivoire

(2000, 2002, 2006)

Miss Waldron's red colobus, P. badius waldroni, of western Ghana and eastern Côte d'Ivoire is teetering on the very brink of extinction (Struhsaker 1999; Oates et al. 2000; Groves 2001; Grubb et al. 2003). Primatologists have searched its known range since 1993, but have failed to see a living animal (Oates et al. 1996/1997; McGraw 1998, 2005; McGraw and Oates 2002). A single skin found in the possession of a hunter near the Ehy Lagoon in southeastern Côte d'Ivoire in early 2002 raised hopes that at least one population of Miss Waldron's red colobus still hangs on, but subsequent fieldwork in this region, including several forest reserves and nearby Isles Ehotiles National Park, has yielded no evidence of living individuals (Kone 2004; Kone and Akpatou 2005; McGraw 2005; Kone et al. 2007).

Through a partnership of Conservation des Espèces et des Populations Animales (CEPA) and the Centre Suisse de Recherches Scientifiques en Côte d'Ivoire (CSRS), Kone et al. (2007) surveyed 14 forest reserves in Côte d'Ivoire between 2004 and 2006, including Isles Ehotiles National Park. These surveys failed to provide any sightings of Miss Waldron's red colobus, only a claim of a single vocalization in Ehotiles in 2006. The forest adjacent to the Ehy Lagoon has not been surveyed since 2002, when no red colobus were found. However, the Ehy forest seems to be the only place in Côte d'Ivoire where a small population of Miss Waldron's red colobus might hang on. The forest is under heavy poaching pressure from Ivorian and Ghanaian hunters, and it is being logged, but Kone et al. (2007) have begun an awareness and education campaign in the villages there. Their plans are to build a community-based conservation system centered on the eight villages surrounding the lagoon. A thorough survey of the forest is needed as a matter of urgency.

In Ghana, very recent surveys (Oates 2006) support earlier suspicions that this monkey is almost certainly extinct in that country (Oates et al. 1996/1997; Struhsaker and Oates 1995). If any animals have managed to survive, the numbers must be very small and it will take heroic efforts to preserve them. Many forms of red colobus are endangered, including three other forms in West Africa: Pennant's red colobus (Procolobus pennantii pennantii) of Bioko Island (see profile in this report), Preuss's red colobus (P. p. preussi) of Cameroon, and the Niger River Delta red colobus (P. p. epieni). In addition, Bouvier's red colobus (P. p. bouvieri) from the Congo Republic has not been seen by scientists for at least 30 years. The plight of these monkeys highlights threats faced by red colobus generally; they have patchy distributions, have suffered extensive habitat degradation and are particularly vulnerable to hunters (Wolfheim 1983; Oates 1996; Grubb and Powell 1999; Oates et al. 2000; Struhsaker 2005). Implementation of a red colobus action plan should be a high conservation priority in Africa.

W. Scott McGraw & John F. Oates

Kipunji (formerly the highland mangabey)

Rungwecebus kipunji (Ehardt, Butynski, Jones & Davenport in Jones et al. 2005)

(formerly Lophocebus kipunji Ehardt, Butynski, Jones & Davenport in Jones et al. 2005)

Tanzania

(2006)

The discovery of this new species of monkey in 2003 was the first in Africa in 20 years (Jones et al. 2005). First classified as Lophocebus kipunji, the highland mangabey, it has since been placed in a new genus Rungwecebus Davenport et al., 2006, on the basis of molecular data from an immature male specimen found in a trap in a farmer's field near Mt. Rungwe, Tanzania. While concerns have been expressed with respect to the designation of this new genus (Ehardt and Butynski 2006b), there is growing molecular (Olson et al. submitted) and also morphological evidence that Rungwecebus is valid. Taxonomic debates aside, this monkey is, without doubt, one of the world's most threatened primates (Davenport 2005; Davenport et al. 2006, submitted; Ehardt and Butynski 2006b). It has been assessed as Critically Endangered, following the IUCN Red List categories and criteria (Ehardt and Butynski 2006b; Hoffmann 2006).

The kipunji is believed to be endemic to two areas in Tanzania that are separated by c.350 km. The Ndundulu population lives at 1,300–1,750 m asl in an area of <700 ha of submontane forest in the Ndundulu Forest Reserve (about 18,000 ha of closed forest) in the Udzungwa Mountains of south-central Tanzania. Only three groups have been confirmed in this population, which is probably no more than 200 individuals in all (C. L. Ehardt unpublished; Ehardt and Butynski 2006b). The Mt. Rungwe-Livingstone population occupies <7,000 ha of degraded submontane and montane forest at 1,750–2,450 m asl in the Mt. Rungwe-Livingstone Mountains (about 562 km², including the Kitulo National Park) of Tanzania's Southern Highlands (Davenport et al. 2006; Davenport et al. submitted). The Rungwe-Livingstone population has received more research attention than the Ndundulu population (Davenport 2005; Davenport et al. 2006, submitted, in prep.; De Luca et al. submitted), although a complete census of both populations has been completed recently (Davenport et al. submitted).

The most serious threat to the Mt. Rungwe-Livingstone population is the destruction of its forest habitat, a process which has proceeded unabated in this area for many years. The Livingstone Forest has been incorporated into Kitulo National Park, which should significantly improve protection for the kipunji groups in this area. Mt. Rungwe, however, remains a Catchment Forest Reserve and the level of protection there continues to be inadequate (Davenport 2006). There is already evidence that the Mt. Rungwe-Kitulo portion of the population consists of a number of isolated sub-populations (Davenport et al. submitted). The situation is compounded by the imminent loss of the narrow (<2 km wide) Bujingijila Forest Corridor that joins Mt. Rungwe and Livingstone (Davenport 2005). With the loss of this corridor, the Mt. Rungwe-Livingstone population will be further fragmented. In addition to the continuing loss of habitat, this population continues to be hunted (Davenport 2005, 2006; Davenport et al. 2005, in prep.). Current rates of forest degradation and loss, especially through logging and charcoal production, could soon lead to the extirpation of the Mt. Rungwe-Livingstone population. What remains of the Mt. Rungwe-Livingstone forests requires immediate and sustained protection (Davenport and Jones 2005; Davenport 2006).

Of particular concern for the Ndundulu population is its extremely small size and the fact that poachers operate in this area (Ehardt and Butynski 2006b). Although local people have historically hunted in other parts of Ndundulu, there is no evidence that kipunji have been hunted here, and human disturbance in this part of the forest is minimal (Davenport and Jones 2005). The Ndundulu population is very small (Jones et al. 2005; Ehardt and Butynski 2006b; Davenport et al. submitted) however, and sizes of the groups thought to comprise this population appear to be smaller than those in the Mt. Rungwe-Livingstone population (Davenport et al. 2006, submitted; Ehardt and Butynski 2006b). These facts, alone, call into question the viability of this population of kipunji (Ehardt and Butynski 2006b; Davenport et al. submitted). Ndundulu Forest Reserve is currently subject to community-based management; however, with sanction from Tanzania's Ministry of Natural Resources and Tourism, Division of Forestry and Beekeeping, Tanzania National Parks is providing rangers to patrol the Ndundulu Forest Reserve, and a ranger post has been established at the edge of Ndundulu Forest.

Found in other forests of the Udzungwa Mountains is another of Tanzania's endemic monkeys, the Sanje mangabey Cercocebus sanjei Mittermeier, 1986, known to science only since 1979 (Homewood and Rodgers 1981). This mangabey is currently listed as Endangered (IUCN 2006), but was included in the 2004–2006 list of the World's 25 Most Endangered Primates (Ehardt and Butynski 2006a). Like the kipunji, it occurs in two populations (separated by c. 100 km) and probably numbers fewer than 1,300 animals (Ehardt et al. 2005). The Mwanihana population occurs entirely within the Udzungwa Mountains National Park, where there is adequate protection and management based on continuing ecological research (Ehardt et al. 2005; Ehardt and Butynski 2006a). The Udzungwa Scarp population is found within the Udzungwa Scarp Forest Reserve, and is under severe threat as a result of habitat degradation and hunting. Thus far, efforts to extend the Udzungwa Mountains National Park to include the Udzungwa Scarp Forest have been unsuccessful. As such, at least 40% of the world's population of the Sanje mangabey remains at substantial risk of decline and eventual extirpation.

These two of Tanzania's endemic species of monkey, both recently discovered, are threatened with extinction due to habitat loss and hunting. Without significant improvement in the protection of the Mt. Rungwe-Livingstone Forest, where roughly 85% of the kipunji monkeys are found, and of the Udzungwa Scarp Forest, where nearly half of the Sanje mangabeys live, these two flagship species will have been part of Africa's known primate diversity for only a brief period in history.

Carolyn L. Ehardt, Thomas M. Butynski & Tim R. B. Davenport

Cross River Gorilla

Gorilla gorilla diehli Matschie, 1904

Nigeria and Cameroon

(2000, 2002, 2004, 2006)

The Cross River gorilla (Gorilla gorilla diehli) is the most western and northern form of gorilla, and is restricted to the forested hills and mountains of the Cameroon-Nigeria border region at the headwaters of the Cross River. It is separated by about 300 km from the nearest population of western lowland gorillas (Gorilla gorilla gorilla), and by around 200 km from the recently-discovered gorilla population in the Ebo Forest of Cameroon. The most recent surveys suggest that between 200 and 300 Cross River gorillas remain. Groups of the gorillas concentrate their activities in eleven localities across a 12,000 km2 range, but genetic research has found evidence that despite their scattered distribution these subpopulations continue to maintain contact through the occasional migration of individuals.

There are currently two protected areas within the Cross River gorillas' range in Nigeria: the Afi Mountain Wildlife Sanctuary and the Okwangwo Division of Cross River National Park. In Cameroon, the Kagwene Gorilla Sanctuary is in the process of gazettement, and planning has begun for the creation of a Takamanda National Park. Beyond those protected areas, about half of the remaining Cross River gorillas occur in community-managed forests and a forest reserve (Mone River in Cameroon). There are many human settlements around the forests where the gorillas occur, and some villages are even enclaved within Okwangwo and Takamanda. The encroachment of farms, dry-season fires set to clear forest or improve pasture, and development activities, such as roads, are continuing threats to the integrity of gorilla habitat. However, large tracts of lower elevation forest remain between the localities where the gorillas are presently concentrated and if these areas can be protected, the animals could expand their range and their population. Genetic evidence suggests that the population of Cross River gorillas was much larger in the past, and that a dramatic decline has occurred over the last 200 years, almost certainly due to the introduction of hunting with firearms. After several years of awareness-raising by conservationists and researchers, hunting of Cross River gorillas for bushmeat has been reduced to a low level but it is still a potential threat, as are wire-snare traps set for other animals.

A conservation action plan for Cross River gorillas has been prepared, based on the deliberations of a workshop held in Calabar, Nigeria, in April 2006, organized by the Wildlife Conservation Society and funded by WWF's African Great Ape Programme and the U.S. Fish and Wildlife Service's Great Ape Conservation Fund (Oates et al. 2007). Among some of the key recommendations made by this workshop are for education and awareness efforts to be expanded, a transboundary conservation committee to be created, and new surveys to be launched in areas that are predicted by remote-sensing image analysis to support gorillas. The workshop recommended completion of the process to create protected areas at Kagwene and Takamanda, as well as the establishment of conservation systems at Mbe (Nigeria) and at Mone River, Mbulu and Bechati-Fossimondi (Cameroon). All these areas require management plans to be developed and implemented.

About 250 km south from the Cross River population, a small isolated population of gorillas occurs in a small portion of the 1,500 km2 forest straddling the Ebo River in southwestern Cameroon, approximately 50 km north of the Sanaga River. Field research undertaken by the Zoological Society of San Diego suggests that five or fewer gorilla groups survive in Ebo, which is also inhabited by ten other diurnal primates, including highly threatened forms such as the drill (Mandrillus leucophaeus), Preuss's red colobus (Procolobus pennantii preussi), and the Gulf of Guinea chimpanzee (Pan troglodytes vellerosus). The taxonomic affinities of the Ebo gorillas are still unclear. Based on measurements of a single skull, they may be most closely related to the gorillas of the inland plateau of Cameroon (south of the Sanaga River), rather than to Cross River gorillas. The Ebo gorilla population only became known to the outside world in 2001; they have been afforded little protection in the past, and the forest's primates are under extreme pressure from bushmeat hunting, given the proximity of the forest to the main urban centers in Cameroon. The Zoological Society of San Diego established a research station there in 2005, and with the full-time presence of researchers, along with technical assistance from WWF's Cameroon Coastal Forests Program, the conservation status of the Ebo Forest has improved and the area is currently being gazetted as a national park.

Jacqui Sunderland-Groves, John F. Oates & Bethan Morgan

Siau Island Tarsier

Tarsius sp. Shekelle et al., in prep.

Indonesia

(2006)

The Siau Island tarsier is a new, undescribed species that is Critically Endangered (A1 acd) and faces an imminent threat of extinction. Shekelle and Salim (in press) used GIS data and field surveys to list specific threats. They include: a very small geographic range, of 125 km², and an even smaller area of occupancy, perhaps as little as 19.4 km²; a high density of humans (311 people per km²) that habitually hunt and eat tarsiers for snack food; and an extent of occurrence that is entirely volcanic in its geological composition, with Mount Karengetang, a massive and highly active volcano, dominating more than 50% of the geographic range of this species. Furthermore, there are no protected areas within its range (Riley 2002; Shekelle and Salim in press; Shekelle et al. 2007), and all captive breeding programs for tarsiers, including several by leading zoos and primate centers, have been dismal failures, leaving no ex situ conservation options for any tarsier species anywhere (Fitch-Snyder 2003). The most reasonable interpretation of the scant data is that population size is very small, in the low thousands at best, and declining (Shekelle and Salim in press). Despite the fact that Sangihe Island is renowned for its Critically Endangered avifauna (Whitten et al. 1987; Whitten 2006), Shekelle and Salim (in press) found that the conservation threat for the tarsier on Siau Island was greater, for every variable measured, than that faced by T. sangirensis on Sangihe Island, which nevertheless is Endangered (B1 2ab). Thus, in spite of the fact that this species has yet to be described and is almost unknown, sufficient available evidence indicates that it teeters on the brink of extinction on an island where the entire endemic fauna and flora are at risk (Shekelle et al. 2007).

In Meyer's (1897) description of T. sangirensis, from Sangihe Island, he included a single skull from Siau Island (in the Dresden Museum, B321, from “Siao”). Sangihe and Siau Islands are part of a volcanic arc and are separated by approximately 60 km of deep ocean, greater than 1,000 m in depth. There is no feasible means for recurrent gene flow between these islands today, nor is there any historical indication of a land connection between these islands. Accordingly, Brandon-Jones et al. (2004) suggested that the Siau Island population is taxonomically distinct. Shekelle visited the island in March 2005 and found acoustic and morphologic evidence that supported taxonomic separation of the Siau Island population. Aside from the skull in Dresden, there is no evidence in the literature of research on this species. Shekelle's surveys found evidence of tarsiers in only two places, on the shores of a small fresh water pond at the extreme southern end of the island, and on a steep cliff face along the east coast road where it runs next to the ocean. Numerous other sites that looked promising, based upon experience with T. sangirensis, turned up no evidence of tarsiers. Interviews with several locals indicated that tarsiers had formerly been common at these sites as recently as 10 years ago, but were now rare or non-existent. They also added that tarsiers were a popular snack food called “tola-tola”, and that it had formerly been common to eat 5 to 10 at a single sitting after hunting them with air rifles. It is unsurprising that tarsiers are no longer found in these areas.

Myron Shekelle & Agus Salim

Horton Plains Slender Loris, Ceylon Mountain Slender Loris

Loris tardigradus nycticeboides Hill, 1942

Sri Lanka

(2004, 2006)

Slender lorises are small, nocturnal primates occurring in southern India and Sri Lanka. The two recognized species, comprised of six subspecies, are readily distinguished from all other primate taxa by large, close-set eyes, pencil-thin limbs, and a long body with only a hint of a tail. Unable to leap, these ninjas of the night move with a fluid and noiseless locomotion. Though they may be slow when startled, all of the slender lorises studied so far can move several kilometers per night, and have home ranges of 1.5 to 10 ha—not small, considering that the various subspecies range in size from 110–350 g.

The smaller of the two species, Loris tardigradus (Linnaeus, 1758), is found only in Sri Lanka's diminishing rainforests. In the 1960s, W. C. Osman Hill used the loris as the symbol of the Wildlife and Nature Protection Society of Sri Lanka, stating that it, being the most mysterious and rarely seen creature of Sri Lanka's jungles, was the most apt symbol for a society dedicated to revealing the unknown in nature. Two subspecies of this taxon, L. t. tardigradus and L. t. nycticeboides, are little better known today. The first long-term study of the red slender loris, L. t. tardigradus, was recently completed by Lilia Bernede of Oxford Brookes University, Oxford, UK. Continuing surveys of this subspecies by Nekaris and field assistants from the University of Ruhuna reveal that it is highly threatened, clinging to Sri Lanka's small remaining rain forest patches, which average only 1,300 ha in size.

The situation for the latter subspecies, L. t. nycticeboides, is no brighter. This rare little loris is found only in Sri Lanka's chilly highlands (where temperatures may drop to -4°C). To cope with these extremes, the Horton Plains slender loris has evolved a thick, woolly coat, which swathes its limbs, giving it the superficial appearance of its Southeast Asian counterpart, the greater slow loris, Nycticebus coucang. Even in 1942, Osman Hill wrote “That the animal is rare in the Horton Plains is evidenced by the fact that Mr. Tunein-Nolthenius has been on the look out for it for the previous twenty years without success.” In 1980, this statement was further qualified by W. W. Phillips who stated that it “would appear to be the rarest of all mammals in Sri Lanka.” This mysterious loris first appeared on this list of the World's 25 Most Endangered Primates in 2004, after Nekaris and Perera had carried out surveys for it at its type locality, the Horton Plains. They found only two animals after 60 km of surveys. This yielded an abundance estimate of 0.08–0.16 animals/km. A return visit in 2004 by Nekaris and colleagues from the Wildlife Heritage Trust yielded only one observation, giving an abundance estimate of 0.02 animals/km. These exceedingly low density estimates spurred Saman Gamage of the University of Ruhuna to lead a team in search of this most elusive of the lorises. Interestingly, after 21 nights of targeted efforts, abundance estimates generated in 2006 were the same: 0.02 animals/km.

On the brighter side, Gamage's team have found this loris in two new localities, Haggala Strict Natural Reserve, and Bomburella forest. An unusual museum specimen uncovered in the Natural History Museum of Colombo examined by Colin Groves also suggests that the range of this species may extend as far as Sri Lanka's Knuckles Range, expanding its known area of extent from 30 km² to 250 km². A search to identify the lorises in this region will be instigated in 2007 by Sandun Perera of Sabaragamuwa University of Sri Lanka.

Although still imperilled by continued habitat loss, gem mining, agricultural encroachment, as well as being hunted and captured for medicines, as pets, and uses resulting from local folklore, there is a glimmer of hope for this small nocturnal primate. Virtually ignored since its discovery in the 1940s, media exposure from this list has now spurred two studies of this primate by local researchers. It is our hope that in 2008, more populations will be discovered, and that the Horton Plains slender loris can sink back into that dubious comfort of being ‘only Endangered.’

K. Anna I. Nekaris

Simakobu or Pig-Tailed Snub-Nose Langur

Simias concolor Miller, 1903

Indonesia (Mentawai Islands)

(2002, 2004, 2006)

The simakobu monkey is serving as the flagship species for a group of endangered primates endemic to the remnants of forest on the 7,000-km2 Mentawai Islands. The four main islands are located 85–135 km off of the west coast of Sumatra and are home to three other primate species—Kloss's gibbon (Hylobates klossii), the Mentawai pig-tailed macaque (Macaca pagensis), and the Mentawai Island leaf langur (Presbytis potenziani). Simias concolor concolor Miller, 1903 inhabits the islands of Sipora, North Pagai, and South Pagai along with several small islets off southern South Pagai. Simias c. siberu Chasen and Kloss, 1927 occurs only on Siberut Island. Where Simias still occurs on the Pagai Islands, it exists at lower densities than on Siberut.

Although the first simakobu specimens were collected in 1902, researchers did not begin studying the Mentawai primates until the 1970s. In 1996, two simakobu groups were habituated to the presence of humans and studied in Betumonga, in the southwestern region of North Pagai Island. Researchers with the Siberut Conservation Project in the Peleonan Forest in northern Siberut are in the process of habituating more simakobu and other primate groups. Simakobus are arboreal quadrupeds that eat leaves, fruits, and flowers, and exhibit a variable social organization.

All four of the Mentawai primates are affected by habitat disturbance and hunting (Whittaker 2006). Although hunting appears to be declining and opportunistic, human encroachment and timber removal are increasing. Of the four Mentawai primates, simakobus seem to be the most sensitive to logging. On the Pagais, density estimates range from a high of 5.17 simakobus per km² in unlogged forests to a significantly lower density of 2.54 ind/km² in forests that were logged in the 1980s (Paciulli 2004). Twenty-five years ago, simakobus were found in areas of mixed primary and secondary forests on Siberut at densities as high as 220 ind/km² (Watanabe 1981). In 1990, however, no evidence could be found of Simias inhabiting several areas on Siberut and the Pagais (Tenaza and Fuentes 1995).

Today, the Mentawai primates continue to exist in some residual forest patches on the Pagais and Sipora, and parts of the 190,500-ha (470,735 acres) Siberut National Park (also a UNESCO Biosphere Reserve) that covers 47% of the island. Thus, while Simias and the other Mentawai primates still survive in spite of human encroachment, hunting, and timber removal, the vast majority of the remaining natural habitat lies outside of officially protected areas. Most of these areas are in logging concessions and could very well be lost in the near future as there is talk of clear cutting in 2008 for oil palm plantations.

Lisa M. Paciulli

Delacour's Langur

Trachypithecus delacouri (Osgood, 1932)

Vietnam

(2000, 2002, 2004, 2006)

Delacour's langur is endemic to Vietnam and occurs in a very restricted area of northern Vietnam which comprises about 5,000 km² between 20°–21°N and 105°–106°E. The distribution is closely linked to the limestone mountain ranges in the provinces of Ninh Binh, Thanh Hoa, Hoa Binh and Ha Nam. Currently there are 19 locations where Delacour's langur is or was known to occur. They are isolated populations and when combined total at most only 400 to 450 km². The extirpation of Delacour's langurs has been reported by local people in three localities that we know of. There is a smaller limestone mountain ridge to the west extending to a large limestone region north of Son La, but there is no evidence of Delacour's langurs in this area. The northwestern border of the distribution is Mai Chau between the Da River in the north and the Ma River in the south. The Da River appears to form the northern border of the species' range. The exact southern boundary is unclear. There are some smaller isolated limestone areas south of the Ma River. The only area south of the Ma River where Delacour's langurs have been confirmed is the limestone complex between Lang Chan and Ngoc Lan, but this population is now most probably extirpated. It seems that this species never occurred south of the Chu River.

During the decades following the discovery of Delacour's langur in 1930 there was only scanty information on its existence and distribution. The first sightings of live animals were reported in 1987 from Cuc Phuong National Park. The most important, and for some subpopulations the only factor for the decline in numbers is poaching, which is not primarily for meat, but for bones, organs and tissues that are used in the preparation of traditional medicines. The 19 isolated wild populations of Delacour's langur have been confirmed over 10 years of surveys and monitoring by the Frankfurt Zoological Society. The total population counted in 1999/2000 was about 280 to 320 individuals. The recorded numbers of animals hunted over the 10 years totaled 320, an annual loss of more than 30 individuals, but the real number is undoubtedly higher. Sixty percent of all existing Delacour's langurs occur in isolated populations with less than twenty animals. The loss of these subpopulations, and consequently sixty percent of the entire population, is foreseeable without management, strict regulations and law enforcement. Surveys in 2004 in two protected areas with important subpopulations, Cuc Phuong National Park and Pu Luong Nature Reserve, showed a decline in numbers of 20% in the last 5 years. It is to be expected that the population in unprotected areas which have yet to be surveyed will show a similar tendency. A reasonable estimate of the current population indicates numbers no higher than 200 to 250 individuals.

Four areas where Delacour's langurs occur are protected: Cuc Phuong National Park, Pu Luong Nature Reserve, Hoa Lu Cultural and Historical Site, and the Van Long Nature Reserve (established in 2001). Van Long Nature Reserve is believed to harbor the largest remaining population of about 60 to 80 animals. They are well protected there due to patrols and close cooperation between the provincial forest protection authorities and Frankfurt Zoological Society. Currently two doctoral students are working in the area, studying the biology and population dynamics of the subpopulation. Efforts to save this species are being led by Tilo Nadler, manager of the Vietnam Primate Conservation Program of Frankfurt Zoological Society and director of the Endangered Primate Rescue Center at Cuc Phuong National Park, established in 1993 primarily to safeguard the future of this and other endangered Vietnamese primates. The Endangered Primate Rescue Center is the only facility which keeps this species. The center started a breeding program with five confiscated animals, and 12 individuals have been born since 1996. The aim is to reintroduce the langurs into well-protected areas to establish additional free ranging populations.

Tilo Nadler & William R. Konstant

Golden-headed Langur or Cat Ba Langur

Trachypithecus poliocephalus poliocephalus (Trouessart, 1911)

Vietnam

(2000, 2002, 2004, 2006)

The golden-headed langur, Trachypithecus p. poliocephalus, is probably the most endangered of the Asian colobines. This species only occurs on the Island of Cat Ba in the Gulf of Tonkin, northeastern Vietnam. The Cat Ba Archipelago is in the world-famous Ha Long Bay, a spectacular karst formation that was invaded by the sea. The golden-headed langur inhabits tropical moist forest on limestone karst hills, and shares this habitat preference with the six to seven taxa of the T. francoisi group. Among these so called karst langurs, the Cat Ba langur and its closest relatives, the white-headed langur, T. p. leucocephalus Tan, 1955, in southern China, and the wide-ranging Francois' langur, T. francoisi (Pousargues, 1898), the northernmost representative of the genus, display the strictest behavioral adaptations to their karst habitat.

There are no systematic and reliable data available on the historic density of the langur population on Cat Ba Island. According to reports of indigenous people the entire island of Cat Ba (140 km²) and some smaller offshore islands were previously densely populated by langurs. Hunting has been the sole cause for the dramatic and rapid population decline from an estimated 2,400–2,700 in the 1960s to only 53 individuals by 2000. The langurs were poached mainly for trade in traditional medicines. Since the implementation of strict protection measures towards the end of 2000, the langur population on Cat Ba Island increased to a current 65 individuals (+22.5%).

Although the growth of the population is encouraging, the overall status of the species is most critical. As a result of habitat fragmentation, the remaining population is now divided into seven isolated sub-populations, five of which include or consist of all-female groups, thus non-reproducing social units. The estimated effective population size is 29 individuals at most. Only three groups are currently reproducing, and the total reproductive output in this species is accordingly low. Since a peak in births in 2003, the reproductive output of the Cat Ba Langur has stagnated at 1–2 offspring per year.

Cat Ba Island and the surrounding area are nationally and internationally recognized for their importance to biodiversity conservation. Cat Ba National Park was established in 1986. It presently covers more than half of the main island. The Cat Ba Archipelago (some 1,500–2,000 large and small islands, cliffs and rocks) was designated a UNESCO Man and Biosphere Reserve in 2004. Despite this, nature and wildlife protection on Cat Ba Island is deficient. Efforts to effectively conserve the langurs and their habitat face major obstacles because of the lack of partnership and commitment with the local communities and the need to better address their aspirations for development, and due to the steadily increasing human population, besides persistent, severe deficiencies in law enforcement. As elsewhere in the region, poaching is driven by increasingly attractive commercial gains in satisfying the immense local and regional demand for wildlife. The strictest protection regime possible is necessary for the survival of all the mammals and other species on Cat Ba that are, like the langurs, targeted by the Asian wildlife trade.

A conservation program for the golden-headed langur on Cat Ba was initiated in November 2000 by the Zoologische Gesellschaft für Arten- und Populationsschutz (ZGAP), München, in cooperation with Allwetterzoo, Munster, Germany. The aim is to provide for their protection, reduce population fragmentation, and contribute to the conservation of the biodiversity on Cat Ba Island in collaboration with Vietnamese authorities.

Roswitha Stenke, Phan Duy Thuc & Tilo Nadler

Western Purple-faced Langur

Semnopithecus vetulus nestor Bennett, 1833

Sri Lanka

(2004, 2006)

Endemic to Sri Lanka, this langur is restricted to a small area of the wet zone in the west of the country, most of which is threatened due to human activities (crops, infrastructure and industry, settlements, deforestation and forest fragmentation, and hunting). Colombo, the capital city of Sri Lanka, is in the center of its very limited range. Hill (1934) indicated that it was common around the capital, but this is no longer the case. Forest cover in Sri Lanka has declined drastically since the late 1950s, and the area of occupancy of this langur has been reduced to a highly fragmented 1,900 km² (Molur et al. 2003). Although still quite numerous (> 10,000), the declines in numbers are expected to have been precipitous—estimated at more 80% in three generations due to urbanization and development.

Western purple-faced langurs are highly arboreal and need good canopy cover, and there are possibly less than three forests that can support viable populations, none of which are protected areas set aside for conservation. The human-modified areas that sustain much of the langur population, such as gardens and rubber plantations, are under private ownership and changing rapidly due to human population expansion and development; large trees are cut down and entire forest patches are destroyed for housing and development. This severely restricts home ranges, isolating the groups, and resulting in escalated conflict with humans and low juvenile recruitment rates (Dela 1998). Long-term studies by Dela (1998) have shown that this taxon is unique in having subpopulations adapted to a diet high in mature/ripe fruit, a feature as yet unrecorded for any other colobine, and are dependent on fruits cultivated by humans.

The geographical range of the species has a very high human population density, and home ranges are being compressed due to loss of tree cover. Censuses are urgently needed to identify forest areas for conservation and to better quantify the decline of subpopulations in space and time, and to provide a better understanding of their demographics (especially reproductive rates, population turnover and dispersal) in the extremely disturbed habitats where they survive today.

Jinie Dela & Noel Rowe

Grey-shanked Douc

Pygathrix cinerea Nadler, 1997

Vietnam

(2000, 2002, 2004, 2006)

The colobine monkeys of the genus Pygathrix are native to Indochina. Until only ten years ago, just two distinct taxa were recognized: the red-shanked douc, Pygathrix nemaeus, named by Linnaeus in 1771, in the northern part of Central Vietnam and Central Laos; and the black-shanked douc, P. nigripes, from South Vietnam and east Cambodia, described exactly a century later by Milne-Edwards. The grey-shanked douc was first described as a subspecies of the red-shanked douc, but genetic studies have since demonstrated a divergence at species level. It occurs in Central Vietnam between 13°30′ and 16°N, and has been recorded in five provinces: Quang Nam, Quang Ngai, Kon Tum, Gia Lai and Binh Dinh. Currently grey-shanked doucs are known only from Vietnam, but records exist close to the border to Laos, and there are photos of hunted animals from southeast Laos and far northeast Cambodia that suggest that the species occurs in small neighboring areas in both countries. Surveys and research on this recently discovered primate have been conducted by the Frankfurt Zoological Society, led by Tilo Nadler, manager of the Vietnam Primate Conservation Program of Frankfurt Zoological Society and director of the Endangered Primate Rescue Center at Cuc Phuong National Park, and Ha Thang Long, biologist at the Rescue Center.

Grey-shanked douc populations are fragmented and estimated to total 600–700 individuals. Their occurrence has been confirmed in eight protected areas: Song Thanh Nature Reserve, Ngoc Linh Nature Reserve, Ba To Cultural and Historical Site, An Toan Nature Reserve, Kon Cha Rang Nature Reserve, Kon Ka Kinh National Park, Mom Ray National Park and A Yun Pa Nature Reserve. However, hunting, the principal threat to the species, is still a problem inside these parks and reserves. Snares are the most commonly used method since gun confiscation programs were carried out in a number of the areas. Often hundreds of traps are installed in trees frequently used by the langur groups, as well as on the ground where they are seen crossing between small forest patches. Trapped animals are often severely injured and mutilated. Forest loss within at least part of the species' range is attributable to the expansion of agriculture, illegal logging and firewood collection. Almost 10,000 ha of forest are destroyed every year in the Central Highlands.

The Endangered Primate Rescue Center has received 37 confiscated grey-shanked douc langurs since 1995, and has begun a breeding program to provide stock for reintroduction in protected forests. Based on information from villagers and forest protection authorities, less than one-quarter of the hunted animals are confiscated alive. Ha Thang Long, the biologist of the Endangered Primate Rescue Center, is studying the species in Central Vietnam specifically to provide recommendations for the establishment of special “Species Protection Areas,” which will promote connectivity between the currently isolated populations in the established parks and reserves.

Ha Thang Long & Tilo Nadler

Tonkin Snub-nosed Monkey

Rhinopithecus avunculus Dollman, 1912

Vietnam

(2000, 2002, 2004, 2006)

The Tonkin snub-nosed monkey is one of four unusual, large Asian colobine monkeys of the genus Rhinopithecus, all of which possess a characteristic turned-up nose. The three other species are endemic to China, while the Tonkin snub-nosed monkey is found only in northern Vietnam. This species was discovered in 1911, collected on perhaps no more than two occasions over the course of the next 50 to 60 years, and subsequently presumed to be extinct by a number of primatologists until it was rediscovered in 1989. Historically the species occurs only east of the Red River between about 21°09′–23°N. Due to massive deforestation and intensive hunting in recent decades, its distribution has become dramatically restricted.

Currently, there are only four known locations with recent evidence where Tonkin snub-nosed monkeys occur, and these are completely isolated. In 1992, a population was found in Na Hang District, Tuyen Quang Province. As a result of the discovery, a nature reserve was established in 1994. The nature reserve comprises two separate areas: the Ban Bung and Tat Ke sectors. A study in 1993 estimated a population of between 95 and 130 individuals in each sector, respectively, which was probably overestimated. A later study, in 2004–2005, found far lower densities, and estimated only 17–22 individuals in the Tat Ke sector. For the subpopulation of Na Hang Nature Reserve, the most serious threat was a hydropower and flood prevention dam project. Construction began in 2002. Some 10,000 workers moved into the area for dam construction, which has increased the demand for wildlife products and firewood. Conservation activities carried out by several organizations have been unsuccessful, and resulted in a reduction of this subpopulation.

A population of about 70 individuals was estimated for Cham Chu Nature Reserve, also in Tuyen Quang Province. Based on local interviews during a survey reported in 1992 the population was believed to have dropped to only 20–40 individuals. A survey in 2006 provided no sightings and no reliable evidence of the survival of the population. Local reports indicate, however, a small group of 8–12 individuals still in the area. A population of about 60–90 Tonkin snub-nosed monkeys was discovered 2001 in Khau Ca, close to Du Gia Nature Reserve, Ha Giang Province. This is the only population which is not immediately threatened. There, public awareness and community participatory activities are being linked to increased protection efforts under the supervision of Fauna & Flora International (FFI). The total population of the Tonkin snub-nosed monkey is believed to be less than 150 individuals.

Le Khac Quyet, Tilo Nadler & William R. Konstant

Hainan Gibbon

Nomascus hainanus (Thomas, 1892)

China (Island of Hainan)

(2000, 2002, 2004, 2006)

The taxonomy of the crested black gibbons, genus Nomascus is still in debate, but experts now believe there are three species: the Hainan gibbon, Nomascus hainanus, the most endangered of any of the gibbons and restricted to the island of Hainan (Geissmann 2003; Geissmann and Chan 2004; Wu et al. 2004; Zhou et al. 2004); the eastern black gibbon, Nomascus nasutus, occurring in northeast Vietnam (Nadler 2003), and adjoining Guangxi Zhuang Autonomous Region, China (Chan et al. in prep.); and the western black gibbon, Nomascus concolor, occurring in central Yunnan, China, and Indochina. A recent study found no molecular differences between the putative subspecies of N. concolor, but significant genetic differences between the forms hainanus and nasutus (Roos et al. 2007). The Hainan gibbon and eastern black gibbon differ in their hair coloration (Geissmann et al. 2000; Mootnick 2006) and territorial calls (La Q. Trung and Trinh D. Hoang 2004). These characteristics, in association with the newly discovered genetic differences, suggest that the Hainan gibbon and eastern black gibbon be considered distinct species (Roos and Nadler 2005; Roos et al. 2007).

Adult male eastern black gibbons are black and can have a slight tinge of brown hair on the chest. Adult male Hainan gibbons are entirely black (Geissmann et al. 2000; Mootnick 2006). Adult female Hainan gibbons and eastern black gibbons vary from a buffish to a beige brown and have a black cap (Geissmann et al. 2000; Mootnick 2006). The adult female Hainan gibbon has a thin, white face ring that is thicker above the mouth and below the orbital ridge. The hair surrounding the face of the female Hainan gibbon creates a rounded appearance encircling the face. The hair grows outwards on the side of the face and in a more downward direction as it gets closer to the chin. This contrasts with the female northern white-cheeked gibbon (Nomascus l. leucogenys), whose facial appearance is slightly similar to the female Hainan gibbon. The hair on the outer sides of the face of the female white-cheeked gibbon grows in a more upward direction giving the face a more triangular appearance. Depending on the amount of humidity, female Nomascus can acquire a more orangey color resulting from their sweat (Mootnick 2006). The only account of a live female eastern black gibbon in close proximity was of a female “Patzi” in the Berlin Zoo whose vocalizations were similar to that of the eastern black gibbon, but her pelage differed in that she had a very long and broad black crown streak that went past the nape, and extended to the brow, tapering to a thin face ring and becoming thicker at the chin (Geissmann et al. 2000; Mootnick 2006). This female had a narrow blackish-brown chest plate slightly wider than the face, beginning at the throat and tapering at the top of the abdomen. At this time Patzi had more black than what has been observed in the wild or in museum specimens of female eastern black gibbons.

The eastern black gibbon was thought to be extinct in southwestern provinces of China in the 1950s. In the 1960s, it was also feared extinct in Vietnam, but was rediscovered after intensive searches in January 2002 by Fauna and Flora International (FFI) biologists La Q. Trung and Trinh D. Hoang (2004). They found five groups totaling 26 individuals in the remaining 3,000 ha of limestone forest of Phong Nam-Ngoc Khe Mountains, Trung Khanh District, northern Cao Bang Province bordering Guangxi in China. Further surveys by the Vietnam Primate Conservation Programme of FFI and Trung Khanh District rangers in November 2004 located 37 individuals (VNA 2004). Recently, a team of researchers from Kadoorie Farm & Botanic Garden (KFBG) and China confirmed 17 eastern black gibbons in three groups in the Bangliang limestone forest of Jingxi County in Guangxi, neighboring the Phong Nam-Ngoc Khe Mountains of Vietnam. Some of the gibbons observed in Bangliang may be the same individuals counted by Vietnamese counterparts as gibbon groups were seen traveling between the two countries (People's Daily Online 2006; Chan et al. in prep.). There is rumor that there might be some eastern black gibbons in Kim Hy Nature Reserve, Bac Kan Province, Vietnam, as well as other border areas in Guangxi, China.

In the 1950s there were estimates of >2,000 Hainan gibbons on the island of Hainan in 866,000 ha of forests across 12 counties (Wang and Quan 1986). By 1989, the Hainan gibbon population was reduced to only 21 gibbons in four groups restricted to Bawangling Nature Reserve (Liu et al. 1989). In 1998 the population was said to be 17 (Kadoorie Farm & Botanic Garden 2001). A gibbon survey in October 2003 found two groups, and two lone males, comprising a total of 13 individuals (Fellowes and Chan 2004; Geissmann and Chan 2004; Chan et al. 2005; Zhou et al. 2005); another survey in 2001–2002 estimated 12–19 individuals in four groups (Wu et al. 2004). In recent months three newborns and at least one lone female have been observed, bringing the world total to 17 individuals (Hainan Daily Online 2007a).

Gibbons generally establish long-term pair bonds, but in Bawangling National Nature Reserve (BNNR) there have been repeated observations of two females in the same group both carrying offspring (Liu et al. 1989; Bleisch and Chen 1991; Hainan Daily Online 2007a). This “non-traditional” group could be the result of older offspring being unable to locate appropriate mates (Wu et al. 2004), limited space to establish new groups (Liu et al. 1989), or could reflect habitual bigyny as in the crested black gibbons of Yunnan (Bleisch and Chen 1991; Fan et al. 2006). If fresh feces could be collected from these individuals, it is possible that nuclear DNA sequencing could determine the relationships and confirm if observations are being conducted on the same group in different locations.

Since 2003, when the first Hainan Gibbon Action Plan was launched (Chan et al. 2005), several teams have continued to work roughly in line with the Plan, though with limited coordination. Conservation actions include surveying the distribution of the Hainan gibbon, providing training of staff to monitor the gibbons, restoring the forest, and community conservation work. One team consists of the KFBG, the Hainan Wildlife Conservation Centre of the Hainan Provincial Forestry Department (HWCC), and BNNR. The second (Franco-Chinese) team consists of East China Normal University of Shanghai (ECNU), the Zoological Society of Paris (PZS), and BNNR. A third team from Fauna and Flora International (FFI) China has also conducted monitoring, training and community work in the recent past.

With only 17 Hainan gibbons and 54 eastern black gibbons confirmed, each surviving in just one small forest block, the Hainan gibbon and eastern black gibbon are among the most critically endangered primates in the world. It is important to gain full support from the surrounding community for conservation of the gibbons and their habitat, possibly by ensuring benefits linked to their compliance with conservation goals, and ensuring longer-term commitment from the government and outside partners. Efforts are underway to contribute to the conservation of the eastern black gibbon in Vietnam with the establishment of community-based protection activities. Since there are unconfirmed reports of gibbon occurrences from other forests, additional surveys need to be conducted in both Guangxi and Hainan (Hainan Daily Online 2007b). There is an urgent need to secure and expand suitable forest for the survival of the few remaining gibbons and their habitats, which will require continued effort and cooperation among all parties.

Alan R. Mootnick, Xiaoming Wang, Pierre Moisson, Bosco P. L. Chan, John R. Fellowes & Tilo Nadler

Western Hoolock Gibbon

Hoolock hoolock (Harlan, 1831)

Bangladesh, India, Myanmar

(2006)

The hoolock gibbon was formerly in the genus Bunopithecus with just one species and two subspecies: B. hoolock hoolock, the western hoolock gibbon, and B. hoolock leuconedys Groves, 1967, the eastern hoolock gibbon from Myanmar and China. Mootnick and Groves (2005) informed that the name Bunopithecus was not valid, and placed it in a new genus, Hoolock, and at the same time argued that the two forms were distinct species (but see Mootnick 2006). The western hoolock gibbon (Hoolock hoolock) occurs in Bangladesh, northeastern India and western Myanmar, west of the Chindwin River. Its range in Myanmar, known from just a few field studies and mostly informal sightings, is restricted to the western parts, delineated from the populations of Hoolock leuconedys by the Chindwin River as far as the head waters in the north. In India and Bangladesh its range is strongly associated with the occurrence of contiguous canopy, broad-leaved, wet evergreen and semi-evergreen forests. The species is an important seed disperser; its diet includes mostly ripe fruits, with some flowers, leaves and shoots.

Western hoolock gibbons face numerous threats in the wild, and are now entirely dependent on human action for their survival. The debilitating threats include habitat encroachment to accommodate ever-growing human populations and immigration, forest clearance for tea cultivation, the practice of jhuming (slash-and-burn cultivation), hunting for food and “medicine” capture for trade, and the degradation and decline in quality of their forests that impacts fruiting trees, canopy cover and the viability of their home ranges. Isolated populations face the additional threats arising from the intrinsic effects of small populations. Some populations surviving in just a few remaining trees are subjected to harassment by locals and to lack of food, and are attacked by dogs while attempting to cross clearings between forest patches.

Based on habitat loss over the last 30–40 years, western hoolock gibbons are estimated to have declined from more than 100,000 (Assam state alone was estimated to have around 80,000 in the early 1970s) to less than 5,000 individuals (a decline of more than 90%). The species was known to occur in good numbers in contiguous forests, which have borne the brunt of persistent human impacts. Isolated forest fragments hold just some few families— numbers insufficient for survival in the mid- to long-term. Apart from some border forests between India and Myanmar, the remaining habitat is fragmented, holding minimal populations of this sort. We have documented the extirpation of western hoolock gibbons from 18 locations over the last 3–5 years; eight in Bangladesh and 10 in India. Bangladesh has about 200 western hoolock gibbons in 22 separate locations, twenty of which have less than 20 individuals each: 17 of these have less than 15 individuals, and 14 have less than 10 individuals. About 100 locations with hoolock gibbons have been recorded in India; 77 have less than 20 individuals, and 47 of these have less than 10 individuals. The Population Viability Analysis (PVA) predicts a 95% decline in the population in Bangladesh and a 75% decline in the population in India over the next two decades based on the current effects of human impacts and the intrinsic factors acting on very small and isolated populations.

The population of the western hoolock gibbon in Myanmar has not been surveyed. West of the Ayeyarwaddy-Chindwin River, there is about 50,000 km² of forest in the Rakhine Yoma region, but much of it is degraded and hunted. The area includes the Rakhine Yoma Elephant Range (about 175,500 ha), managed by the Nature and Wildlife Conservation Division of the Forest Department of Myanmar, in Rakhine State, in the lower part of the country (about 17°N). There are other forested areas farther to the north, including the Chin Hills Complex and the Naga Hills area, but they are considered unsafe for travelers. No published information is available on the current range and status of the western hoolock in Myanmar. Warren Brockelman has been carrying out surveys of the eastern hoolock, Hoolock leuconedys Groves, 1967, in accessible protected areas east of the Chindwin River in Myanmar since 2005, and preliminary results indicate that the situation there is considerably more encouraging, with relatively large populations still surviving. The population trends for the western hoolock observed over recent years in Bangladesh and northeast India indicate a very rapid decline in numbers and immediate measures are required by their governments, forest departments, local communities and NGOs.

Sally Walker, Sanjay Molur & Warren Y. Brockelman

Sumatran Orangutan

Pongo abelii Lesson, 1827

Indonesia (Sumatra)

(2000, 2002, 2004, 2006)

Sumatran and Bornean (Pongo pygmaeus Linnaeus, 1760) orangutans, now recognized as two distinct species, comprise the genus Pongo. While there are considered to be three subspecies of P. pygmaeus, the Sumatran orangutan is regarded as a single taxonomic unit. The viability of all taxa is in question, but the Sumatran orangutan faces a more immediate extinction risk than the Bornean, and is considered Critically Endangered.

The species is endemic to Sumatra, Indonesia, and is now entirely restricted to remaining lowland forests in Nanggroe Aceh Darussalam (NAD) and North Sumatra Provinces. About 7,000 individuals remain (based largely on 2002 satellite imagery), surviving in 13 fragmented habitat units stretching from northern NAD, south to the Batang Toru River in North Sumatra, with a notable gap in their distribution immediately west of Lake Toba. The southernmost populations may be genetically and culturally distinct from their more northern relatives. The largest populations live within NAD province, where until recently, a separatist conflict made monitoring and conservation work problematic.

By far the most significant populations, totaling about 5,600 animals, are found within the Leuser Ecosystem, a 26,000 km² conservation area established by presidential decree that encompasses the smaller Gunung Leuser National Park (10,950 km²; itself part of the Sumatran Rainforest World Heritage Site) and the 1,025 km² Singkil Swamps Wildlife Reserve within its boundaries. The Ecosystem and the national park within it form the only conservation area of note where viable wild populations of the Sumatran orangutan, Sumatran tiger, Sumatran rhinoceros and Sumatran elephant, each of which is endangered in itself, still occur living side by side. The National Park, however, is predominantly high mountains, and as the orangutan is a predominantly lowland creature, rarely being found above 1,000 m asl, the majority occur within the larger Ecosystem but outside the National Park. For example, the Ecosystem harbors c.75% of the remaining 7,000 Sumatran orangutans whilst only 24% are found within the National Park and 20% within the Singkil Swamps Wildlife Reserve.

Throughout its range, the primary threat to Sumatran orangutans is logging, both legal and illegal, which often leads to total conversion of forests for agriculture or oil palm plantations. Although exact figures are still unavailable, primary lowland forests in Sumatra have been devastated over the last 20 years. One analysis of satellite imagery concluded that habitat supporting around 1,000 orangutans was being lost each year in the Leuser Ecosystem alone during the late 90's (van Schaik et al. 2001). This was largely due to legal logging concessions and conversion of lowland forests to palm oil estates, but also illegal logging and encroachment in some places. Fortunately, however, the rate of habitat loss decreased markedly in many areas during the Aceh civil conflict, as activities in the forests became unsafe, and as a result of a moratorium imposed on logging in the province by the Aceh government. Orangutan populations have nevertheless plummeted in regions that have been affected by logging. Even small scale illegal logging can reduce local orangutan densities by as much as 60% in Sumatra (Rao and van Schaik 1997). At least six of the remaining seven populations containing over 250 individuals have experienced between 10 and 15% annual habitat loss due to logging. Encroachment and conversion, especially by settlers fleeing the conflict in NAD and migrants from Nias Island, have accelerated habitat loss in some parts. Relocation of people from coastal areas and an increase in demand for timber after the 2004 tsunami poses a significant new threat. Several proposed new roads (known as the Ladia Galaska project) will lead to a major increase in fragmentation of remaining orangutan populations. Throughout their range orangutans are sometimes killed as pests along forest edges as they raid agricultural crops, and in the far south of their range they are occasionally still hunted as food. A small but significant pet trade in young Sumatran orangutans also persists.

Key conservation interventions rely heavily on a dramatic and rapid improvement in enforcement of wildlife and forest laws and far greater consideration for environmental issues in spatial planning decisions. Implementing patrols, improving law enforcement, stopping illegal logging, halting legal logging and forest conversion to plantations, promoting forest restoration, halting road construction, addressing human-orangutan conflict, and providing connectivity in the landscape to allow for genetic exchange are all seen as pre-requisites for the species' survival. If current rates of habitat loss persist a further 50% of Sumatran orangutans will vanish within a decade. However, there is as much reason to believe the rate of decline will actually increase due to higher demand for timber, fragmentation by roads, expansion of plantations and general population pressure, as there is for mitigation of these threats. Solutions to conserve the remaining lowland primary forests are urgently needed.

Ian Singleton, Susie Ellis & Mark Leighton

Variegated or Brown Spider Monkey

Ateles hybridus I. Geoffroy, 1829

Colombia, Venezuela

(2006)

There are two recognized subspecies of the variegated or brown spider monkey. Ateles hybridus brunneus Gray, 1870 is restricted to Colombia, occurring between the lower Ríos Cauca and Magdalena in the Departments of Bolívar, Antioquia and Caldas. Ateles h. hybridus occurs east from the right bank of the Río Magdalena extending into western Venezuela. Both subspecies are Critically Endangered due to habitat loss, hunting and the pet trade.

The large size, slow reproductive rate (single offspring at 3–4 year intervals) and generally low population densities of spider monkeys make them especially vulnerable to hunting. Historically, A. hybridus has suffered from habitat destruction, and only 0.67% of the current remaining A. hybridus distribution is protected. Most of its range has been converted to farms for agriculture and cattle.

Ateles h. brunneus has a small geographic range in a region where forest loss, degradation and fragmentation is widespread. Currently the remaining populations are surrounded by human populations, compounding the already high level of threat. Only 9% of their potential range remains as continuous forest. Surveys have been conducted to determine the density of this subspecies in Maceo and Puerto Berrio (Antioquia). To date just one group of eight individuals has been found in an area of 1,000 ha. A refuge remains, however, in the Serranía San Lucas in southern Bolivar, identified as an important site for the establishment of a national park. A protected area is highly necessary for this subspecies, that also would include two other threatened endemic primates, the white-footed tamarin, Saguinus leucopus, and the woolly monkey, Lagothrix lugens.

Ateles h. hybridus is extremely endangered due to habitat destruction in both Colombia and Venezuela. This subspecies can be found in three protected areas in Venezuela, but little is known about the population densities and local threats there.

Ateles hybridus can be found in at least six zoos in Colombia, presenting problems of surplus animals and consanguinity. This species is suffering also from the pet trade; about 20 confiscated individuals are currently in residence in four rescue centers and need to be relocated. There is an urgent need for surveys to establish areas with populations of this species and to propose conservation measures. An ex situ breeding program is also necessary to maintain healthy and viable captive populations.

Erwin Palacios & Alba Lucia Morales-Jiménez

Brown-headed Spider Monkey

Ateles fusciceps fusciceps Gray, 1866

Ecuador, Colombia

(2006)

Ateles fusciceps lives in Central and South America, from southeast Panama to Ecuador, west of the Andes along the Chocó Ecoregion. It is a diurnal species that inhabits mostly evergreen humid tropical forest. It is strictly arboreal and prefers the uppermost levels of the canopy. The species lives in groups of up to 35 individuals and its diet comprises mainly ripe fruits, but also flowers and leaves of a number of different species. The subspecies Ateles fusciceps fusciceps inhabits the Pacific coast of Ecuador and possibly southern Colombia, in an altitudinal range between 100 and 1,700 m above sea level. This subspecies is listed as Critically Endangered (CR) in the Red List of the IUCN as well as the Red Book of Mammals of Ecuador (Tirira 2001b), due to its restricted distribution and the small size of its natural populations. Strong hunting pressure and high deforestation rates are the most critical threats for the species; destruction of the humid tropical forest in western Ecuador has surpassed 80% of its original area. Tirira (2003, 2004) presented information on the historical and current distribution of the species, reporting several localities where it is locally extinct, including the type locality (Hacienda Chinipamba, west of Ibarra, Intag sector, Imbabura Province), the whole central coast of Ecuador and the forests of the Ríos Cayapas, San Miguel, Ónzole and Santiago, in the Esmeraldas Province. Currently there are only two areas known where populations of Ateles fusciceps fusciceps remain, but their ecological characteristics and conservation status are unknown. One population is found north of the Río Mira, within the protected area “Reserva Etnica Awá” close to the Colombian border; the other, to the south, is largely within the limits of another protected area: the “Reserva Ecológica Cotacachi-Cayapas” and neighboring forest (mainly in a private reserve: “Reserva Biológica Los Cedros”). There is little information on the numbers and population densities of this species in the wild. Gavilanes-Endara (2006) reported 1.2 individuals/km2 in the Reserva Biológica Los Cedros. Its presence in Colombia is uncertain, but there is a record of A. fusciceps for Barbacoas, Nariño Department, that needs to be confirmed.

Diego Tirira & Alba Lucia Morales-Jiménez

Peruvian Yellow-tailed Woolly Monkey

Oreonax flavicauda (Humboldt, 1812)

Peru

(2000, 2006)

The Peruvian yellow-tailed woolly monkey, Oreonax flavicauda, is endemic to Peru, and is found only in a small area in the Tropical Andes. Oreonax flavicauda is known to persist only in primary premontane, montane and cloud forest between 1,500 to 2,700 m asl (Leo Luna 1982; Butchart et al. 1995; DeLuycker 2007). When O. flavicauda was first rediscovered in 1974, populations existed in the Departments of Loreto and La Libertad (Leo Luna 1980), but they have now been restricted to irregular, scattered parts of only two Departments, Amazonas and San Martín. There are no current estimates of remaining population numbers. Indiscriminate clear-cutting of primary cloud forest is the principal threat to this species, and its habitat has been largely deforested, resulting in a greatly fragmented landscape.

Very little is known about the ecology and behavior of the yellow-tailed woolly monkey. Results from studies in the early 1980s indicated that the sizes of its multi-male/multi-female groups ranged from 5 to 18 individuals. Oreonax flavicauda has been seen to eat a variety of fruits, flowers, leaves, lichens, leaf bases of bromeliads, epiphyte roots and bulbs, and possibly insects (Leo Luna 1982; DeLuycker 2007). In a recent field survey, an unusually large group (17–20 individuals) was encountered in areas relatively close to agricultural plots, which may indicate that due to recent and on-going loss of habitat they are finding less suitable habitat areas. The species appears to be highly sensitive to alterations in its habitat (Leo Luna 1987; DeLuycker 2007). Due to the forest disturbance resulting from illegal logging, O. flavicauda decreases its use of the area (Leo Luna 1984), often retreating further into high-altitude forests far away from human settlement in order to use large tracts of forest. In 1981, it was estimated that O. flavicauda occurred in low densities, from 0.25 to 1 group per km² (Leo Luna 1987). It is also suspected to have a large home range (DeLuycker 2007). The species is known to be present in the Río Abiseo National Park (2,745 km²), the Alto Mayo Protected Forest (1,820 km²), and the Reserved Zone Cordillera de Colán (641 km²), which was established in 2002 with assistance from the Asociación Peruana para la Conservación de la Naturaleza (APECO).

The current area occupied by O. flavicauda is unknown. In 1981, it was estimated that its potential forested habitat was at least 11,240 km² (Leo Luna 1984). It was predicted that at least 1,600 km² would be deforested for agriculture by 1991 (Leo Luna 1984). Projecting this value for 15 additional years, and using a very conservative similar rate of deforestation, this leaves an estimated 7,240 km² of potential habitat area. This estimate is probably much lower, due to a high rate of migration to the area combined with unregulated land use. In addition, much or most of this forest is now highly fragmented or isolated from other tracts of forest. Oreonax flavicauda has likely declined drastically in numbers due to a big reduction in their area of occupancy and a decrease in the quality of their habitat.

Clearing the forest for agriculture continues at an alarming rate, even in the Protected Forest of Alto Mayo (BPAM). It has been estimated that between 2,300 and 2,500 ha of forest have been destroyed in BPAM (ParksWatch, Peru). The forest of the BPAM is now considerably fragmented, a result of lack of enforcement and a substantial human population living in the Protected Forest itself. The BPAM also suffers from illegal selective logging. Members of several botanical expeditions conducted within the BPAM over the last ten years reported having never seen nor heard O. flavicauda there (M. Dillon, personal comm.). Towns that were previously connected only by footpaths are now more accessible due to road construction. For example, Vista Alegre, a town in the Department of Amazonas, and where O. flavicauda has been reported, has plans to build a road in the near future; the first in the region. Additionally, O. flavicauda has been extirpated from all but the most distant and isolated forests on the eastern side of the Río Alto Mayo. Illegal hunting still occurs, and if the monkeys are encountered, they are likely shot, because of their large size, conspicuousness, and trusting behavior toward humans. The species' velvety, thick, long fur, its skin and skull, and yellow genital hair-tuft are sought after as trophy items, and make this species a target for hunters even when they do not hunt it for subsistence. Infants taken when their mothers are shot are sold in markets as pets.

There is very little information on the biology and natural history of this species, resulting mainly from the difficulties imposed by the mountainous and precipitous terrain where it lives. A complete, range-wide survey of its cloud forest habitat is urgently needed to develop plans to protect the remaining populations of Oreonax flavicauda. These surveys should also include population genetic studies, to examine genetic variability and the viability of existing populations. Urgent conservation initiatives necessary for the yellow-tailed woolly monkey's survival include: increased protection within designated parks, reserves, and protected forests, which currently lack enforcement; the establishment of a contiguous area of protected forest, to create a biological corridor; the establishment of a national park or reserve in the semi-isolated Valle de los Chilchos area; control of illegal logging; purchase of land; the provision of alternative economic models for local communities living along buffer zones, in order to prevent further migration into the primary cloud forests; and the implementation of a strong conservation education plan.

Anneke M. DeLuycker & Eckhard W. Heymann