The Lake Kutubu Wildlife Management Area (WMA) covers approximately 23,500 ha of freshwater lake and surrounding forest environments on the southern slopes of New Guinea's central cordillera in mainland Papua New Guinea (PNG). Ornithological work within the WMA spans more than 50 years, although most of the data are available only in the grey literature and are difficult to obtain. In light of a proposed review of PNG's protected area network, we collate bird records from the WMA and draw upon data from the nearby Agogo Range to consider the potential for additional species to occur within the gazetted area. The WMA inventory stands at 216 species, nearly one-third of all species resident or regularly occurring in the New Guinea region. The high species richness is attributable to the presence of a variety of forest and wetland habitats spanning nearly 600 m elevation, supporting bird species characteristic of lowland, hill and lower montane environments. Resident avifauna include five IUCN threatened or Near Threatened species (New Guinea Harpy Eagle Harpyopsis novaeguineae, Gurney's Eagle Aquila gurneyi, New Guinea Vulturine Parrot Psittrichas fulgidus, Striated Lorikeet Charmosyna multistriata and Banded Yellow Robin Gennaeodryas placens) and the restricted-range Greater Melampitta Megalampitta gigantea. Geographic and elevational range extensions are reported for numerous taxa, and recent data are presented to better document the distributional relationships of species pairs in the genera Talegalla, Megapodius, Micropsitta and Lonchura, and of races of Brown Cuckoo-Dove Macropygia amboinensis and Double-eyed Fig Parrot Cyclopsitta diophthalma.
Papua New Guinea's (PNG's) protected area system covers c.4% of its land surface (Adams et al. 2017, Leverington et al. 2017). Most of the gazetted land is contained within Wildlife Management Areas (WMAs), a legal instrument tailored to function in the context of customary land tenure which accounts for approximately 97% of land in PNG (Allen 2009). Under the WMA system, customary landowners, often in partnership with the government or NGOs, define the boundaries of the area to be protected, establish rules governing the use of its natural resources, and elect local representatives to a Wildlife Management Committee responsible for its regulation and management.
The management of PNG's protected areas has been problematic (Melick et al. 2012). Forest loss and degradation continue apace (Bryan et al. 2015), WMAs have no legal protection against exploitation (Leverington et al. 2017) and, in recent decades, the average rate of loss in most WMAs has been similar to that in unprotected areas (Shearman & Bryan 2011).
In 2014, the PNG government launched its Policy on Protected Areas outlining guidelines for improving the governance and management of protected areas and the biodiversity values they contain (Independent State of Papua New Guinea 2014). The scheme will review the values of existing protected areas and the wishes of customary landowners, and decide how each area should be defined under the future Protected Area Network. Following review, each area's protected status may be confirmed, reclassified or degazetted.
Within this context, our knowledge of the avifauna present within PNG's protected areas is highly variable. Detailed information is available for sites that are regularly visited by ornithologists (e.g. Varirata National Park: Eastwood 1997) or that have hosted detailed scientific research programmes (e.g. Crater Mountain WMA and YUS Conservation Area: Mack & Wright 1996, Sinclair 2002, Freeman et al. 2013, Mack 2014). At the other extreme, some sites remain biologically unexplored, while others have been the subject of one or more surveys but the data are reported only in the grey literature and the summary information is difficult to obtain.
Lake Kutubu WMA is located in Southern Highlands Province, on the southern slopes of New Guinea's central cordillera c.530 km north-west of the national capital Port Moresby (Fig. 1). It was established in 1992 ‘to conserve the outstanding and internationally significant scenic, geophysical and biodiversity values of the Lake Kutubu WMA, and safeguard the interests and maintain the cultural integrity of its traditional owners’ (quoted in D'Cruz 2008: 8–9). Multiple bird surveys have been conducted in the area, with the most recent efforts continuing to further our knowledge of the region's avifauna. Most of the relevant data appear in unpublished NGO reports (cf. Schodde & Hitchcock 1968). Here, we review the body of ornithological work conducted within Lake Kutubu WMA, and draw upon the results of surveys conducted on the nearby Agogo Range to consider the potential for additional species to occur in the WMA. This paper is based on a report previously published online (Woxvold & Legra 2018) and incorporates data from additional surveys not available at the time that report was written.
Study area
Lake Kutubu is mainland PNG's largest perched lake. Lying at c.820 m above sea level, and covering more than 4,900 ha, it is flanked by high-relief terrain with forested slopes rising more than 400 m above lake level within 1 km of its shore. Lake Kutubu WMA covers some 23,497 ha of the lake and the environs (Leverington et al. 2017) to above 1,380 m at Mount Kemenagi near the southern shore (Fig. 1).
Located in the ‘Kikori-Lake Kutubu Karst Area' of the Southern Fold Mountains, the geology is characterised by Tertiary limestones and Pleistocene volcanic deposits forming a north-west-trending series of ridges, plateaux and valleys (Löffler 1977, Bryan & Shearman 2008). Polygonal karst dominates major topographic features south and west of the lake, including the Kutubu anticline and, immediately outside the WMA boundary, the Agogo Range (here considered to include the Iagifu and Hedinia anticlines; Fig. 1). Recent alluvial deposits are located at each end of the nearly 19 km-long lake. Rainfall is ‘continuously heavy’ (little seasonality) and totals more than 4,000 mm annually (McAlpine et al. 1983, Bryan & Shearman 2008). The lake is drained from the north-west via the Soro River which forms part of the Kikori River drainage.
Three major natural vegetation groupings are mapped under the PNG Forest Inventory Mapping System (FIMS) (Hammermaster & Saunders 1995): (1) wooded freshwater swamps—dominated by complexes of Sago Metroxylon sagu / Pandanus swamp woodland and mixed swamp forest on flood-prone alluvium at each end of the lake, with reedbeds (including Phragmites) present at the lake margins; (2) hill forest—medium-crowned forest on slopes below 1,000 m, with Nothofagus present on most upper slopes and ridges more than a few hundred metres from the lakeshore; and (3) lower montane forest—on terrain above 1,000 m, alone or in complex form as structural variants (small- / very small-crowned) with or without Nothofagus prominent in the canopy.
Figure 1.
The Lake Kutubu Wildlife Management Area and places mentioned in the text. Land above 1,000 m is shaded darker grey.
The Lake Kutubu and adjacent Mubi River valleys are the traditional lands of the Foi people (Regis 2000). First contact with Europeans did not occur until the 1930s (Champion 1940). Half a century later, in the late 1980s commercial reserves of oil and gas were discovered in the uplands of the Kikori basin. Petroleum production is ongoing, and the Lake Kutubu area hosts a variety of support facilities and infrastructure.
Vegetation is predominantly intact except in areas cleared for oil and gas infrastructure and around local settlements. Local resident settlements are presently concentrated along the margins of the lake and at a few sites beside roads. Secondary forest in regenerating garden sites and natural forest degraded by local resource extraction is present around settlements and along some roads.
Existing data
The first ornithologist to visit Lake Kutubu was R. Schodde of the Commonwealth Scientific and Industrial Research Organization (CSIRO). In September–October 1961 he spent four weeks surveying birds at the north-west end of the lake between the Soro River outlet and the Mubi River valley (Schodde & Hitchcock 1968). In addition to general field observations, Schodde collected 132 specimens of 79 species (held at the Australian National Wildlife Collection, Canberra; ANWC). The records are well annotated, with most encounters traceable to within the WMA. Exceptions include those species shot by local Papua New Guinean assistants whose movements were not documented but are presumed to have been restricted to the local vicinity.
In partnership with industry leaders, in 1994 the World Wildlife Fund (WWF) initiated the Kikori Integrated Conservation and Development Project (KICDP), currently termed the Kikori Basin Conservation Program, aimed at preserving biodiversity within the Kikori drainage (Leary et al. 1996, McCall & Flemming 2000).
As part of the first KICDP survey programme, in 1994 and 1995 I. Burrows surveyed birds (1) within and immediately adjacent to Lake Kutubu WMA around Moro and the lake area, and (2) more than 4 km south and west of the WMA in the Agogo Range (at c.900–1,100 m; Hartshorn et al. 1994, Burrows 1995). No trapping was undertaken, and during a total of ≤10 observation days most of the forest survey effort was expended in the Agogo Range. Only the 1994 reconnaissance report (Hartshorn et al. 1994) distinguishes records from the Agogo Range and the Moro–Kutubu areas. Thus, in terms of locating records within the WMA boundary, the provenance of many species observed by Burrows only in 1995 cannot be determined. Nevertheless, all surveys were conducted at elevations within those covered by the WMA, and most species of uncertain provenance have been recorded locally by other workers.
During 1997–99, R. Jaensch (Wetlands International) and various co-workers surveyed birds on four occasions on and around Lake Kutubu (Jaensch undated a,b, Jaensch & Kulmoi undated). No trapping was undertaken. Jaensch made additional brief visits to the Agogo Range outside the WMA and annotated his results sufficiently to distinguish records from each site.
On behalf of WWF, JMD & KDB conducted repeat-visit surveys of the Moro–Lake Kutubu–Agogo Range area in 1998, 1999, 2001, 2003, 2006 and 2007. Their observation-based surveys (no trapping) were conducted at 790–1,440 m while based (1) at Moro near Lake Kutubu, and (2) at the ‘Ridge Camp’, a permanent industrial base located outside the WMA in the Agogo Range. Originally reported as a combined Agogo Range / Moro–Kutubu dataset (Diamond & Bishop 2003, 2007), the list of species recorded within the WMA is here presented separately.
Most recently, birds were surveyed by IAW & LL within the WMA in May 2017 (Woxvold & Legra 2018), and the Agogo Range in 2015 (Woxvold & Legra 2017), 2017 and 2018 (IAW & LL unpubl.). Survey methods included active searches, camera-trapping, mist-netting and screening of automated bioacoustic recorder data. Survey coverage and effort are described in detail in Woxvold & Legra (2018).
Insofar as locality information can be determined with certainty, the results of the above surveys are combined to provide a comprehensive list of birds recorded to date in the Lake Kutubu WMA. While the WMA was delineated to exclude converted habitats of the Moro camp and airstrip, birds recorded at these sites are here included among the WMA records as this area of exclusion is immediately surrounded by the WMA.
Conventions used
Taxonomy follows Beehler & Pratt (2016). Species appearing in square brackets (in text, tables and appendices) were only provisionally identified to species level; although not definitively identified, encounters are considered most likely to have involved the species named and these records are included in the overall species tally. Records denoted by ‘?’ in Appendices 1 and 3 are considered less certain and are not included in site totals.
Species of conservation concern include those listed in the IUCN Red List of Threatened Species (IUCN 2019) as threatened (Vulnerable—VU; no Endangered or Critically Endangered bird species have been recorded in the Lake Kutubu WMA), Near Threatened (NT) or Data Deficient (DD) and those listed as Protected (P) under the PNG Fauna (Protection & Control) Act 1966. The list of nationally protected species was obtained from Kula & George (1996). Restricted-range (RR) species are those having a total global breeding range smaller than 50,000 km2 (Stattersfield et al. 1998).
Results
At least 216 bird species from 63 families have been recorded in the Lake Kutubu WMA and / or immediately adjacent to the WMA in the Moro facilities area. The taxa recorded by various workers are listed in Appendix 1 along with their conservation status, trapping frequencies and residency / migratory status.
Nine species were recorded within the WMA for the first time during the most recent surveys in 2017–18. Three of these were confirmed present by camera-trapping alone—Wattled Brushturkey Aepypodius arfakianus, Cinnamon Ground Dove Gallicolumba rufigula and Thick-billed Ground Pigeon Trugon terrestris. Mottled Meliphaga Meliphaga mimikae was identified from mist-net captures, while other novel records were seen and / or heard during active searches and / or recorded by SM3 recorders—Buff-banded Rail Hypotaenidia philippensis, Sooty Owl Tyto tenebricosa, Nankeen Kestrel Falco cenchroides, Greater Melampitta Megalampitta gigantea and Eurasian Tree Sparrow Passer montanus.
During a review of prior studies, adjustments were made to the status / identity of seven previously recorded taxa. Reasons for these adjustments are outlined in detail in Appendix 2. The changes are as follows.
Removal from the WMA list of four unconfirmed species whose presence requires a range extension and / or is better assigned to a locally occurring species—Southern Cassowary Casuarius casuarius, Yellow-legged Brushturkey Talegalla fuscirostris, crowned pigeon Goura sp. and Fan-tailed Cuckoo Cacomantis flabelliformis.
In the absence of confirmed records, where two closely related species may occur locally and are difficult to distinguish in the field, the expansion of single taxon listings to dual-possibility records—White-throated Eurostopodus mystacalis / Papuan Nightjar E. papuensis, Uniform Aerodramus vanikorensis / Mountain Swiftlet A. hirundinaceus and Yellow-billed Syma torotoro / Mountain Kingfisher S. megarhyncha.
Including data from all surveys, the Lake Kutubu WMA avifauna includes some 192 breeding resident species and 23 species that occur in the Kikori basin only or predominantly as non-breeding migrants (Appendix 1). The residency status of the Eurostopodus nightjar recorded by Schodde (Schodde & Hitchcock 1968) is uncertain—it may have been a resident species (E. papuensis) or an Australian breeding migrant (E. mystacalis) (see Appendix 2). At least five breeding resident species have local regional populations seasonally augmented by non-breeding visitors from Australia—Green Pygmy Goose Nettapus pulchellus, Pacific Black Duck Anas superciliosa, Australasian Grebe Tachybaptus novaehollandiae, Eastern Koel Eudynamys orientalis and Oriental Dollarbird Eurystomus orientalis. Most migratory birds recorded in the WMA breed outside New Guinea in Australia (17 / 23; 73.9%). Six migratory species breed in the Northern Hemisphere and visit New Guinea during the austral summer—Oriental Cuckoo Cuculus optatus, Grey-tailed Tattler Tringa brevipes, Common Sandpiper Actitis hypoleucos, Red-necked Stint Calidris ruficollis, Sharp-tailed Sandpiper C. acuminata and Gray's Grasshopper Warbler Locustella fasciolata.
Eighteen species of conservation concern have been recorded in the WMA. They include seven birds listed by IUCN as Vulnerable or Near Threatened, 13 that are Protected under PNG law and three restricted-range species. IUCN listed and restricted-range species are discussed individually below (Species accounts).
One non-native bird species was recorded, the commensal Passer montanus having recently established itself across much of the Moro facilities area. P. montanus was first recorded in mainland PNG at Port Moresby in April 2009 (Gregory 2009). An accomplished colonist, its recent arrival has been followed by a rapid expansion into settled areas with the first record from nearby Gulf Province at Kerema in 2011 (Woxvold et al. 2015). This is the first reported occurrence in Southern Highlands Province, although it is likely already to be more widespread there.
Species accounts
Species accounts follow (in taxonomic order) for conservation listed taxa, restricted-range species, rarely recorded species, and wherever records (post-Schodde & Hitchcock 1968) extend a species' known geographic or elevational range. Unless otherwise stated, summary information on status and distribution is taken from Beehler & Pratt (2016).
RED-LEGGED BRUSHTURKEY Talegalla jobiensis
Occupies northern New Guinea from Yapen Island and the Mamberamo basin east to Milne Bay. Until recently, confirmed records from the southern watershed were restricted to a few sites in the Owen Stanley Range (Aroa River area) and the upper Purari River basin (Jones et al. 1995, Mack & Wright 1996; J. Ross Sinclair in litt. 2015). The shy behaviour of megapodes, and the difficulty in distinguishing closely related species based on vocalisations alone, has meant that some prior southern upland records were reported only at genus level, or followed earlier published authorities in assuming the species to be the southern lowland resident T. fuscirostris. However, emerging evidence suggests that T. jobiensis replaces T. fuscirostris at upland sites across much of southern mainland PNG with confirmed records in most major catchments from the upper Fly River east to the Moroka area (Beehler & Pratt 2016; IAW unpubl.). Camera-trapping in 2017 showed T. jobiensis to be fairly common (nine events on seven cameras; Fig. 2a) in hill forest and at the edge of wooded swamps north of the lake. Outside the WMA, it has been camera-trapped at 925–1,400 m in the nearby Agogo Range (Woxvold & Legra 2017). These are the first confirmed records from the Kikori basin.
[NEW GUINEA SCRUBFOWL Megapodius decollatus]
Until recently, M. decollatus was thought to predominantly occur in northern New Guinea, with Orange-footed Scrubfowl M. reinwardt replacing it across most of the southern watershed (Jones et al. 1995, Pratt & Beehler 2015). However, there is growing evidence that M. decollatus is widespread on the southern slopes of the central cordillera where it replaces M. reinwardt in upland environments (Woxvold et al. 2015, Beehler & Pratt 2016, Woxvold & Legra 2017). Unfortunately, many prior records of Megapodius from southern New Guinea, including from the Moro–Lake Kutubu–Agogo Range area, refer to Common (Dusky) Scrubfowl M. freycinet, within which both M. decollatus and M. reinwardt (inter alia) were formerly subsumed (Mayr 1938). Difficulties with observing these species in the field, and with collecting detailed and reliable information from local informants, mean that such records cannot be safely assigned to either taxon. M. decollatus has been camera-trapped at 920–1,400 m in forest on limestone in the Agogo Range, c.3–5 km outside the WMA (Woxvold & Legra 2017), and to the south-east at 540 m in the Gobe operations area (IAW unpubl.). These are the first confirmed records from the Kikori basin. Within the WMA, Megapodius calls were recorded at three SM3 stations in 2017. M. reinwardt certainly occupies lowland habitats further downstream in the Kikori basin (Woxvold 2018a,b). However, based on recent evidence regarding the distribution and habitat requirements of these species in New Guinea's southern watershed, and on confirmed records from comparable habitats nearby, the Lake Kutubu WMA records are here provisionally assigned to M. decollatus.
GREEN PYGMY GOOSE Nettapus pulchellus
Twenty-nine individuals seen on the lake by Jaensch (undated a) represent a high-elevation record for this species (Coates 1985).
BROWN CUCKOO-DOVE Macropygia amboinensis
Beehler & Pratt (2016) subsumed all New Guinean subspecies east of the Bird's Neck within M. a. cinereiceps. Simultaneously, Ng et al. (2016) rearranged the M. amboinensis species complex along bioacoustic lines, proposing that populations with monosyllabic calls in eastern New Guinea be treated as a separate species—Amboyna Cuckoo-Dove M. amboinensis—from those with disyllabic call motifs in the west—Sultan's Cuckoo-Dove M. doreya. Ng et al. (2016) noted that the contact zone of M. amboinensis and M. doreya is poorly understood, but mapped the distribution of M. amboinensis in southern New Guinea west to near the PNG / Indonesian border, aligning with other accounts of the range of M. a. goldiei (Baptista et al. 1997) which they include within M. amboinensis. However, birds in the Kikori River basin, including within the Lake Kutubu WMA, have disyllabic calls characteristic of M. doreya.
THICK-BILLED GROUND PIGEON Trugon terrestris
A large terrestrial pigeon endemic to lowland and foothill forests of New Guinea and Salawati Island. An individual camera-trapped in hill forest at 865 m on 7 May 2017 (Fig. 2b) is the highest confirmed record for the species (previously up to 640 m).
RUFESCENT IMPERIAL PIGEON Ducula chalconota
Two observed by Burrows ‘along the swing bridge road Lake Kutubu’ on 22 March 1994, and subsequently reported by Jaensch. While the exact location is unknown, the reference to Lake Kutubu suggests that this is the lowest reported elevation for this species by nearly 200 m (previously as low as 1,000 m).
GREY-TAILED TATTLER Tringa brevipes (NT) / RED-NECKED STINT Calidris ruficollis (NT)
Regionally present at highest density in tidal environments, in 1961 Schodde observed small numbers at the edge of Lake Kutubu—one C. ruficollis and ‘occasional groups of two to five birds’ of T. brevipes (Schodde & Hitchcock 1968: 23). In 2007 JMD & KDB recorded a single C. ruficollis at Moro airstrip.
BAT HAWK Macheiramphus alcinus
Rare in New Guinea from the lowlands to above 1,100 m. On 18 October 2007, KDB observed one in flight over a ridge above Kaimari Creek.
NEW GUINEA HARPY EAGLE Harpyopsis novaeguineae (VU, P)
Occupies forested habitats from sea level to above 3,000 m. Visually inconspicuous (does not soar), it is most readily detected by its distinctive and far-carrying call. It was observed by JMD & KDB within and / or near the WMA in most survey years (1998, 2001, 2002, 2006, 2007), and the species has been regularly recorded by other observers in the Agogo Range (Hartshorn et al. 1994, Burrows 1995; IAW unpubl.).
GURNEY'S EAGLE Aquila gurneyi (NT)
Widespread but very sparse in forested habitats throughout New Guinea, mostly below 1,000 m. Occasionally observed high over forest in the WMA—in 2001 a duo near the Soro River (JMD & KDB), and in 2017 singles at the north end of the lake and near Moro (IAW & LL).
WHITE-BELLIED SEA EAGLE Haliaeetus leucogaster
Observed over Lake Kutubu in 1998 and 2007 (Diamond & Bishop 2007) and in 2017. This is the highest reported location in New Guinea (previously up to 540 m; reported at 1,700 m on Sulawesi: Thiollay 1994).
NEW GUINEA VULTURINE PARROT Psittrichas fulgidus (VU, P)
Endemic to New Guinea where it inhabits hill and lower montane forest normally below 1,600 m. A nomadic and specialist frugivore, it feeds almost exclusively on a select variety of figs (Ficus spp.; Fig. 2c) (Mack & Wright 1998). P. fulgidus is regularly encountered in small numbers in the WMA where it has been recorded by all surveyors (Appendix 1). It is a mobile and easily detected species and multiple records at the same site may involve repeat encounters with the same individuals. Outside the WMA, in 2015 ten were observed at a single fruiting fig in the Agogo Range (Woxvold & Legra 2017).
STRIATED LORIKEET Charmosyna multistriata (NT, RR)
A rare blossom nomad, endemic to the southern slopes of the central cordillera from the Snow Mountains in Indonesia east into PNG as far as Crater Mountain (Mack & Wright 1996). On 5 May 1998, JMD & KDB observed a flock of six birds at 825 m near the Soro River.
DOUBLE-EYED FIG PARROT Cyclopsitta diophthalma
A widespread and geographically variable species with seven subspecies currently recognised from New Guinea, its satellite islands and north-east Australia (Gill & Donsker 2019). In southern New Guinea there are no published lowland records east of the Fly River (Coates 1985, Beehler & Pratt 2016). However, recent surveys reveal that C. diophthalma is widespread in the Kikori-Purari region. Observed in the Lake Kutubu WMA by JMD & KDB (April 2003 and May 2006), elsewhere it has been seen in the nearby Agogo Range (IAW unpubl.), in the Kikori basin lowlands (below 500 m) at Gobe, Kantobo, Pinini Creek and at Kopi (Diamond & Bishop 2003, 2007) and in the Purari basin lowlands (IAW unpubl.). It is often stated that C. diophthalma and Orange-breasted Fig Parrot C. gulielmitertii replace each other locally (Coates 1985, Beehler & Pratt 2016). However, both species have been recorded in Lake Kutubu WMA and at all of the above-listed lowland sites, and in the Purari lowlands they have been observed together in the same fruiting tree. It is uncertain which subspecies is present in the WMA. A lone male observed by IAW in the Agogo Range showed a blue spot in front of the eye and a red forecrown with a yellow posterior margin, recalling the nominate northern mainland form C. d. diophthalma. In contrast, a pair observed by IAW in the Purari basin lowlands (below 200 m) was most similar to C. d. aruensis, the male showing no obvious blue eye spot or yellow margin to the red forecrown, and the female lacked red facial markings but had grey cheeks and a blue forecrown. As provisionally observed below for two Micropsitta species, it is possible that these two Cyclopsitta subspecies overlap and separate altitudinally within the Kikori–Purari region.
YELLOW-CAPPED PYGMY PARROT Micropsitta keiensis / BUFF-FACED PYGMY PARROT M. pusio
The distributional limits of Micropsitta in southern New Guinea are poorly known. Of two similar-looking lowland species, M. keiensis occurs in the west and M. pusio in the east, with a potential zone of contact / overlap somewhere in the Gulf of Papua hinterland. Recent field guides and regional checklists report both species in the Kikori basin (Pratt & Beehler 2015, Beehler & Pratt 2016, Gregory 2017), although it is unclear on what records these assessments are based (Beehler & Pratt 2016 cite Schodde & Hitchcock 1968 as the source for a Lake Kutubu record of M. pusio, but no such record appears in that report). Both species apparently occur in the Lake Kutubu WMA, where Burrows observed a pair of M. pusio ‘along the swamp road, Lake Kutubu' (1995: 36) and KDB saw M. keiensis in 2007 (in addition to sightings of unidentified Micropsitta in other years). Burrows’ record is the westernmost sighting of M. pusio from the southern watershed, while M. keiensis occurs east at least as far as the lower Purari River basin (IAW unpubl.). Other Kutubu area reports refer to M. pusio / keiensis (Jaensch undated a) or to M. pusio without describing the encounter (Jaensch undated b). The Kikori–Purari region may represent a zone of overlap within which these two species separate altitudinally. Elsewhere in the Kikori basin, all confirmed records involve M. keiensis at elevations below 200 m—at Iviri and Keboi Kerowa (Leary undated), in the Wau Creek proposed WMA and at Uro Creek (Woxvold 2018a,b). In the Purari basin, M. pusio was reported from uplands in Crater Mountain WMA (above 850 m; Mack & Wright 1996), whereas M. keiensis is the only species confirmed present at lower elevations (all records below 250 m; IAW unpubl.). Further observations are required to confirm this pattern.
TROPICAL SCRUBWREN Sericornis beccarii × LARGE SCRUBWREN S. nouhuysi (PERPLEXING SCRUBWREN S. virgatus)
There is much confusion over the taxonomy of some Sericornis populations occupying the upper hill–lower montane zone of central and western New Guinea. Morphologically highly variable, they are considered by some to be hybrid populations involving S. nouhuysi and S. beccarii (e.g. Coates 1990, Beehler & Pratt 2016). Others treat them as a valid species—Perplexing Scrubwren S. virgatus (e.g. Diamond 1985, Gregory 2007, Gill & Donsker 2019)—although there is disagreement as to which populations this taxon should include. Scrubwrens of this troublesome group are present in the Kikori basin. Within the Lake Kutubu WMA, an adult male collected by Schodde at 820 m at the north-west end of the lake is most similar to S. beccarii, with a black-and-white pattern on the forehead and an incomplete white eye-ring (Schodde & Hitchcock 1968, Coates 1990). Outside the WMA, duller forms more similar to S. nouhuysi have been observed in the lower montane limestone forests of the Agogo Range and at Gobe 50 km south-east of Lake Kutubu (Diamond & Bishop 2003, 2007; IAW unpubl.). These birds show an obscure / thin buffy eye-ring and obscure pale tips to the wing-coverts. Their song—a tinkling Gerygone-like song of a couple of repeated short phrases—is the same as that of other populations encountered by JMD on the outlying mountain ranges on New Guinea's north and north-west coast.
BLACK THICKET FANTAIL Rhipidura maculipectus
Endemic to the lowland wet-floor forests of south and west New Guinea and satellite islands. Confirmed present in swamp forest north-west of the lake in 2006 and 2007 (Diamond & Bishop 2007), songs provisionally attributed to this species were fairly common there in 2017 and 2018. This is the highest reported elevation for the species.
TWELVE-WIRED BIRD-OF-PARADISE Seleucidis melanoleuca (P)
Endemic to lowland forests of New Guinea and Salawati Island, especially swamp forest with Metroxylon sagu and Pandanus spp. (Coates 1990, Frith & Beehler 1998). Recorded locally by JMD & KDB in 2001 and 2007, the Lake Kutubu swamps are the highest recorded locality for this species (elsewhere up to 180 m).
GREATER MELAMPITTA Megalampitta gigantea (RR)
One of New Guinea's most enigmatic birds, M. gigantea is a near-specialist inhabitant of forested karst where it is believed to roost and nest underground (Diamond 1983, Gregory 1995). It is a restricted-range species known from a few localities across New Guinea at 500–1,400 m. On 7 May 2017 one was heard from the road in an area of limestone forest north-west of Lake Kutubu near the KP 89–90 section of the pipeline right-of-way (ROW). Elsewhere in the Kikori basin it is fairly common in the Agogo Range and at Gobe (Diamond & Bishop 2003, 2007, Woxvold & Legra 2017; Fig. 2d).
[RUFOUS MONARCH Symposiachrus rubiensis]
An uncommon bird endemic to lowland forests of western and central New Guinea. There are few reports from PNG's southern watershed, including two from the Strickland basin—in the Nomad River area (Bell 1970) and near the Rentoul River (IAW unpubl.). In 1994, Burrows observed a ‘male seen at close range…in forest by the Moro camp’ (Burrows 1995: 37). Given the large extension in both altitudinal (not previously reported above 175 m) and geographic range, and the lack of records from subsequent surveys, this record is here treated as provisional.
BANDED YELLOW ROBIN Gennaeodryas placens (NT, RR)
Endemic to New Guinea and Batanta Island (Indonesia), with isolated populations scattered in hill and lower montane forest at 100–1,450 m. First reported from the WMA by Schodde who collected one from forest near Moro (Schodde & Hitchcock 1968), it was later recorded by JMD & KDB (in 2001, 2003, 2006, 2007) and on 9 May 2017 two were heard in forest on limestone at c. 950 m along the KP 89–90 section of the pipeline ROW.
GRAY'S GRASSHOPPER WARBLER Locustella fasciolata
There are few records of this Northern Hemisphere migrant from eastern New Guinea. Within the WMA, on 18 October 2007 JMD & KDB observed one in dense secondary scrub (<1 m tall) at the north-east corner of the WMA. Elsewhere locally, this species was observed in the Agogo Range in 2001.
STREAK-HEADED MANNIKIN Lonchura tristissima / WHITE-SPOTTED MANNIKIN L. leucosticta
The distributional limits of these uncommon and closely related species are poorly known. L. leucosticta occupies southern lowlands from the Lorentz River in Indonesia east at least to the Hegigio–Kikori basin in PNG (Coates 1990). L. tristissima occurs in northern New Guinea and the far east and west of the southern watershed; in southern PNG it has been recorded on the south-east peninsula as far west as the Lohiki River between the Purari and Lakekamu basins. Within Lake Kutubu WMA, KDB observed both species along the Swamp Road at the north-west end of the lake—L. tristissima in 2003 and L. leucosticta in 2006.
Discussion
The Lake Kutubu WMA supports a rich and varied avifaunal community. Surveys conducted to date have recorded nearly one-third of all bird species resident or regularly occurring in the New Guinea region (including satellite islands and excluding seabirds and vagrants: 216 / 696, 31.0%). The high species richness is attributable both to the diverse set of environments present and to the high accumulated survey effort spanning more than 50 years. The diversity, conservation value and potential for additional species within the WMA are discussed below.
Forest environments.—These habitats support the majority of bird species present within the WMA—of 216 bird species recorded, 170 (78.7%) occur in forest environments, most of which are forest-dependent (cannot persist in converted habitats alone). All resident (non-migratory) conservation listed and restricted-range bird species confirmed present in the WMA are dependent on forest habitats.
The WMA supports a wide range of forest environments. Approximately 160 km2 of upper hill and lower montane forests span nearly 600 m elevation across a variety of substrates, including limestone karst, non-calcareous sediments and volcanic slopes. In addition, some 19.6 km2 of swamp forest / woodland provide an unusually high example of a typically lowland forest ecosystem. Elevation exerts a marked influence on the structure of New Guinean bird communities (Diamond 1972, Beehler 1982), and while some forest birds are capable of utilising all of these environments, several species strongly prefer, or are specialist inhabitants of, just one or a few of these vegetation types. Resident forest birds typical of the upper hill–lower montane transition zone (around 1,000 m) on which the WMA is centred include (but are not limited to) Spotted Honeyeater Xanthotis polygrammus, Goldenface Pachycare flavogriseum, Papuan Cicadabird Edolisoma incertum, Drongo Fantail Chaetorhynchus papuensis, Crinkle-collared Manucode Manucodia chalybatus, Megalampitta gigantea, Black-winged Monarch Monarcha frater, White-eyed Robin Pachycephalopsis poliosoma and White-rumped Robin Peneothello bimaculata. A number of montane birds normally found above 1,000 m are also confirmed present, including Aepypodius arfakiensis, Pygmy Lorikeet Charmosyna wilhelminae, Goldie's Lorikeet Psitteuteles goldiei, Red-breasted Pygmy Parrot Micropsitta bruijnii, Mottled Berryhunter Rhagologus leucostigma and Black Fantail Rhipidura atra. Finally, lowland forest species reported at record or unusually high elevations within the WMA include Trugon terrestris, Little Bronze Cuckoo Chalcites minutillus, Yellow-streaked Lory Chalcopsitta scintillata, Streak-headed Honeyeater Pycnopygius stictocephalus, Large-billed Gerygone Gerygone magnirostris, Lowland Peltops Peltops blainvillii, Seleucidis melanoleucus, King Bird of Paradise Cicinnurus regius, [Symposiachrus rubiensis] and Black-sided Robin Poecilodryas hypoleuca. The well-integrated complex of multiple forest ecosystems present in the WMA thus supports a rich forest bird community that differs in composition among sites within a small geographic area.
The WMA forests are well connected with extensive areas of both similar and additional ecosystem types, including montane forest above 2,000 m and lowland forest below 500 m, both of which occur within 10 km of the WMA boundary. The WMA is thus positioned to support a variety of wide-ranging landscape-level nomadic bird species, including various large frugivores and birds of prey that may not permanently reside there.
The WMA's forests face a variety of pressures. Localised conversions to settlements and gardens were formerly largely confined to the lake's margins and islands (Schodde & Hitchcock 1968). Subsequent infrastructure development and local population growth has seen these losses expand to areas along the road networks within the north-west and north-east margins of the WMA (Fig. 1). As well as local losses, small-scale resource harvesting has degraded some areas of forest near settlements and along the road network. Other recent losses are industry based; while the Moro facilities area was excluded from the WMA limits, recent pipeline construction has converted a narrow, c.8 km-long ROW of hill, lower montane and swamp forest environments within the north-west margin of the WMA (Fig. 1).
Logging presents an additional threat (D'Cruz 2008). More than 49 km2 of the proposed Kutubu–Poroma logging concession (under the PNG Forest Authority draft National Forest Plan) overlaps the Lake Kutubu WMA at its north-east edge (Fig. 1). As of mid 2019 no commercial logging had taken place within the concession (PNG Forest Observatory, http://forest.pngsdf.com/; IAW pers. obs.).
Despite these threats, extensive areas of undisturbed forest remain in the Lake Kutubu WMA. These include much of the wooded swamps and c.80 km2 of hill and lower montane forest on the broad limestone ridge of the Kutubu anticline south of the lake. Swamplands and forest on karst are generally unsuitable for gardening and settlement, and are prohibited from logging under PNG law (PNGFA 1996). These areas are expected to remain largely intact into the foreseeable future, and are sufficient to support viable populations of most resident forest bird species.
Lake Kutubu and its environs are the most frequently surveyed area within the Kikori basin. Despite this effort, each new survey reveals the presence of additional birds, with the latest surveys in 2017–18 adding six forest species to the Lake Kutubu WMA list, all of them resident breeders. It follows that additional species probably remain undetected within the WMA. Notably, the Kutubu anticline includes the highest point within the WMA, reaching over 1,380 m at Mount Kemenagi in the south-east, and its limestone forests are unsurveyed.
The Agogo Range lies immediately south of and parallel to the Kutubu anticline, and its forests have been visited by most ornithologists who have worked the Kutubu area (with the exception of Schodde). Given their proximity and the similarity in habitat and elevation, it is reasonable to expect that birds recorded on the Agogo Range also occur on the Kutubu anticline ridge within the southern sector of the Lake Kutubu WMA. Appendix 3 lists 29 bird species not recorded within the WMA, plus four species only provisionally recorded in the WMA, that have been observed in the Agogo Range by the present authors and / or Burrows (1995). Nearly all of these (31 / 33; 93.9%) are forest bird species, including three nationally Protected birds of paradise—Carola's Parotia Parotia carolae, Superb Bird of Paradise Lophorina superba and Black-billed Sicklebill Drepanornis albertisi.
Wetland environments.—Twenty-four wetland species have been recorded on the lake, rivers and adjacent low vegetated swamps. They are listed in Table 1, along with their residency / migratory status and numbers reported by Schodde (Schodde & Hitchcock 1968) and Jaensch (undated a). Ten recorded wetland species breed locally in southern New Guinea. Breeding has not been reported within the WMA, though this may be an artefact of under-sampling. For species such as Nettapus pulchellus, Anas superciliosa, Tachybaptus novaehollandiae, White-browed Crake Amaurornis cinerea, Dusky Moorhen Gallinula tenebrosa and Australian Reed Warbler Acrocephalus australis, all of which prefer to breed along the vegetated margins of lakes and slow-moving freshwater systems, Lake Kutubu may represent an important breeding site within the region (for example at the province scale). Others such as Little Ringed Plover Charadrius dubius, Azure Kingfisher Ceyx azureus and Torrent Flycatcher Monachella muelleriana are better adapted to smaller waterways and / or fast-flowing rivers that are well represented across the local region. Haliaeetus leucogaster is predominantly a bird of coastal and estuarine environments; Lake Kutubu may support one or more breeding pairs, or they may occur locally as non-breeding visitors. Understanding the importance of the WMA to breeding waterbirds would require additional surveys of vegetated wetlands at the margins of the lake and larger watercourses, and discussions with local residents.
TABLE 1
Birds of rivers and wetlands, their residency / migratory status (Res / Mig), and notes on abundance by Schodde (Schodde & Hitchcock 1968; ‘RS') and Jaensch (undated a; ‘RJ'). Res / Mig status indicates: BR—breeding resident species; M—species that occur in New Guinea only as non-breeding migrants; BR/M—breeding residents with populations seasonally augmented by non-breeding visitors, and a widespread local breeding range potentially overlapping the study area; M(BR)—breeding residents augmented by non-breeding visitors but known breeding sites are localised and lie outside the Kikori basin.
Fourteen migratory wetland species have been recorded in the WMA (Table 1). Ten of these breed in Australia or are known to breed in New Guinea only outside of the Kikori–Purari area. Four are migratory shorebirds that breed in the Northern Hemisphere—Tringa brevipes, Common Sandpiper Actitis hypoleucos, Calidris ruficollis and Sharp-tailed Sandpiper C. acuminata. Lake Kutubu does not contain extensive areas of tidal mudflats that are typically required to support large numbers of Palearctic shorebirds, though it may regularly host larger congregations of migrants that breed in Australia or elsewhere in New Guinea. For example, numbers of Little Pied Cormorant Microcarbo melanoleucos recorded by Schodde and Jaensch (Table 1) may represent locally significant congregations—while they are much smaller than flock sizes recorded in the middle and lower Fly River wetlands of Western Province (Bishop 2005; up to c.9,000 birds: Gregory et al. 1996), they represent the highest concentrations reported to date for the Kikori–Purari systems (Beehler & Pratt 2016; IAW unpubl.).
Numerous additional wetland species have been observed in the expansive system of riverine and estuarine wetlands in the lower Kikori basin (summarised in Woxvold 2018b), many of which may regularly visit Lake Kutubu.
Conclusions
Lake Kutubu WMA is set in one of the world's most biologically diverse and endemically rich terrestrial regions (Olson & Dinerstein 1998, Brooks et al. 2006). More than one-third of all New Guinean bird species have been recorded within the WMA and / or the adjacent Agogo Range. The high species richness is attributable to the presence of multiple habitats, including a variety of dryland forest, open-water wetland and swamp vegetation types, spanning an elevational range of nearly 600 m within a small geographic area.
Resident avifauna include five IUCN threatened or Near Threatened species—Harpyopsis novaeguineae, Aquila gurneyi, Psittrichas fulgidus, Charmosyna multistriata and Gennaeodryas placens—and a suite of nationally Protected and New Guinean endemic taxa, including three restricted-range bird species—Charmosyna multistriata, Megalampitta gigantea and Gennaeodryas placens. Lake Kutubu WMA is the only PNG protected area in which Megalampitta gigantea is known to occur.
The area is potentially of great interest to international birdwatchers. ‘Adventuring into eco-tourism’ is one of four reasons for establishment of the Lake Kutubu WMA listed in its Protected Area Register. In addition to the spectacular scenery afforded by the lake and surrounding landscape, the region's avifauna may play a key role in supporting a sustainable local ecotourism industry.
Acknowledgements
IAW & LL are grateful to ExxonMobil PNG Limited for their funding and logistical support. They are especially indebted to Dr Jane Mogina and Stephen Richards for their vision and efforts in facilitating the multi-disciplinary 2017 biodiversity surveys. Thanks also to Kyle Armstrong and Stephen Richards for deploying SM3 automated sound recorders, and to Pita Amik, Kyle Armstrong and Enock Kale for deploying mist-nets. Anita Mosby, Chris Muller and Pagi Toko provided additional support and company in the field. Bird surveys were conducted in accordance with the permitting procedures of the PNG Conservation and Environment Protection Authority (CEPA). JMD and KDB thank the World Wildlife Fund, the National Geographic Society, Chevron, and Oil Search (PNG) Ltd. for their support. Thane Pratt and Mary LeCroy provided valuable comments on the submitted draft.
References:
Appendices
Appendix 1
Birds recorded in the Lake Kutubu WMA and immediate environs. Conservation status is shown in brackets after the English name for species listed by the IUCN as Vulnerable (VU) and Near Threatened (NT), species Protected (P) under Papua New Guinean law and restricted-range species (RR). Observers—Schodde (RS), Burrows (IB), Jaensch (RJ), JMD & KDB (D-B), IAW & LL (W-L). Square brackets indicate provisional records (uncertain but probable; see Conventions used). Capture rates for the 2017 survey (2017 capt.) are shown as the camera-trapping rate (Relative Abundance Index, proportion <1) and the number of birds mist-netted (integers with the suffix ‘n'). Residency / migratory (Res / Mig) status indicates: BR—breeding resident species; M—species that occur in New Guinea only as non-breeding migrants; BR/M—breeding residents with populations seasonally augmented by non-breeding visitors, and widespread local breeding range potentially overlapping the study area; M(BR)—breeding residents augmented by non-breeding visitors, but known breeding sites are localised and outside of the Kikori basin; t—birds of terrestrial environments, including forest, converted lands and aerial foraging species; w—birds of wetlands, including lakes, rivers and streams; wt—species of both wetland and open terrestrial environments; data from Coates (1985, 1990) and Beehler & Pratt (2016).
Appendix 2
The following accounts outline reasoning for adjustment to the status / identity of prior recorded species. They exclude recent taxonomic adjustments where there is no confusion over the identity of the recorded species.
SOUTHERN CASSOWARY Casuarius casuarius
A lowland species (most records below 300 m) replaced in upland environments, and on steep terrain in some lowland areas, by C. bennetti. The identity of cassowaries within Lake Kutubu WMA is yet to be confirmed. Schodde & Hitchcock (1968) presumed both species present based on reports from local residents and European officers. This is higher than all confirmed localities for C. casuarius in New Guinea and, given the unreliability of many second-hand accounts, requires confirmation from direct field sightings (Beehler & Pratt 2016). Until there is evidence to prove otherwise, all WMA records are provisionally referred to C. bennetti, which is known to occur locally outside the WMA in the Agogo Range (Woxvold & Legra 2017) and downstream in the Gobe area.
YELLOW-LEGGED BRUSHTURKEY Talegalla fuscirostris
A lowland species with one confirmed record above 400 m, on the Sogeri Plateau in Varirata National Park near Port Moresby where the species is known to breed (Richards & Rowland 1995). Emerging evidence suggests that T. jobiensis replaces T. fuscirostris in upland sites across much of southern mainland Papua New Guinea (see Species accounts), with the latter potentially occupying isolated hill-zone sites of relatively gentle terrain (such as at Varirata). Schodde & Hitchcock (1968) reported flushing a bird with ‘pale yellowish feet’ (R. Schodde in litt. 2015), implying T. fuscirostris, in the Mubi River valley. The Mubi River valley includes the largest area of flat alluvial terrain locally present, though this lies mostly outside of the WMA boundary. On similar terrain within the WMA (see Species accounts), camera-trapping revealed T. jobiensis to be fairly common with no images taken of T. fuscirostris. Given the fleeting nature and uncertain location (with respect to the WMA boundary) of Schodde's sighting, his record of T. fuscirostris is here excluded from the WMA tally. Burrows (Hartshorn et al. 1994) and Diamond & Bishop (2003, 2007) also reported T. fuscirostris from the Moro / Kutubu and Agogo Range areas. However, T. jobiensis is the only Talegalla confirmed present in the Agogo Range (Woxvold & Legra 2017) and Lake Kutubu WMA, and it is likely that, as many have done before them, these surveyors were interpreting fleeting glimpses and / or aural encounters based on incomplete distribution data available at the time. Until there is evidence to prove otherwise, these records are provisionally ascribed to T. jobiensis.
SOUTHERN CROWNED PIGEON Goura scheepmakeri
Crowned pigeons are terrestrial-foraging species endemic to the New Guinea lowlands where they prefer forest on gentle terrain. Schodde & Hitchcock (1968: 29) stated that ‘Goura pigeons … were reported by the CSIRO Resources Survey forest botanist … from the primary rainforest between Kutubu station and the Mubi River'. There are no other reports of crowned pigeons from above 500 m, and this record is excluded from subsequent regional handbooks or checklists (Coates 1985, Beehler & Pratt 2016). Without good views, inexperienced observers may confuse other large terrestrial birds such as Otidiphaps nobilis, Trugon terrestris or even megapodes for crowned pigeons. The Kutubu Goura record is here excluded from the WMA list.
FAN-TAILED CUCKOO Cacomantis flabelliformis
A ‘tentative identification’ by Jaensch (undated a) for the Moro / Lake Kutubu area, potentially within range of the rarely recorded migratory Australian subspecies C. f. flabelliformis (distribution poorly known) but below that of resident montane C. f. excitus (Beehler & Pratt 2016). The locality is within the elevational range of the similar looking, and almost identical sounding, common resident Chestnut-breasted Cuckoo C. castaneiventris, a bird confirmed present by other observers. Jaensch's record is here provisionally reassigned to the latter species.
WHITE-THROATED NIGHTJAR Eurostopodus mystacalis / PAPUAN NIGHTJAR E. papuensis
Schodde reported Eurostopodus nightjars from forest clearings near Moro, ‘tentatively' identifying them as E. papuensis, a poorly known species endemic to the lowlands of New Guinea and Salawati Island, ‘on account of the absence of large white marks in the wings and tail and the general locality and habitat, which should exclude [Archbold's Nightjar] E. archboldi’ (Schodde & Hitchcock 1968: 34). Another possible species is E. mystacalis, a non-breeding migrant from Australia that may remain in the area as late as September–October (Beehler & Pratt 2016). The highest reported elevation for E. papuensis is 400 m; that for E. mystacalis is above 1,500 m (Coates 1985, Beehler & Pratt 2016). Until their identity is confirmed, rather than invoking an elevational record for E. papuensis, the Moro nightjars are here recorded as Eurostopodus mystacalis / E. papuensis.
UNIFORM SWIFTLET Aerodramus vanikorensis / MOUNTAIN SWIFTLET A. hirundinaceus
Lake Kutubu WMA is located in an elevational zone of overlap for A. vanikorensis and A. hirundinaceus, two common and widespread species that are indistinguishable in flight. Aerodramus are common in the WMA and have been reported variously as A. vanikorensis? (Schodde & Hitchcock 1968), A. hirundinaceus (Hartshorn et al. 1994, Burrows 1995, Jaensch & Kulmoi undated), A. hirundinaceus? (Jaensch undated a), Aerodramus sp. (Jaensch undated b) and A. hirundinaceus and / or A. vanikorensis (Diamond & Bishop 2003, 2007). Until identifications are confirmed (requiring birds in the hand), all Aerodramus records are here presented as A. vanikorensis / hirundinaceus (Appendix 1). It is acknowledged that the rare Bare-legged Swiftlet A. nuditarsus and / or Three-toed Swiftlet A. papuensis may also occur locally; we consider that these larger species are (at least by some observers) distinguishable in the field and, if present, would occur at lower density than the common smaller species, so that A. vanikorensis / hirundinaceus would account for some, if not all, Aerodramus swiftlets observed by various workers.
Appendix 3
Possible additional species recorded in comparable habitats in the nearby Agogo Range by (observers) Burrows (IB), JMD & KDB (D-B), and IAW & LL (W-L) (some birds recorded by Burrows may have been recorded within the WMA but this cannot be ascertained from his report; see text). The symbol ‘[WMA]’ appears after the English name for species confirmed present in the Agogo Range and provisionally recorded within the WMA. Conservation status is shown in brackets after the English name for species Protected (P) under Papua New Guinean law. Residency / migratory (Res / Mig) status indicates: BR—breeding resident species; M—species that occur in New Guinea only as non-breeding migrants; BR/M—breeding residents with populations seasonally augmented by non-breeding visitors, and widespread local breeding range potentially overlapping the study area; M(BR)—breeding residents augmented by non-breeding visitors, but known breeding sites are localised and outside of the Kikori basin; t—birds of terrestrial environments, including forest, open areas and aerial foraging species; w—birds of wetlands, including lakes, rivers and streams; data from Coates (1985, 1990) and Beehler & Pratt (2016).
