White-sand vegetation (WSV) enclaves occur throughout Amazonia. WSV, known in Brazil as campina or campinarana, possesses peculiar floral and faunal communities, different from those in adjacent forests but with biogeographic affinities to those in similar ecosystems far distant. Recent ornithological studies of these ‘islands’ have yielded new taxa for science and enabled a better understanding of the zoogeography of many poorly known species in Amazonia. Here we report the results of an ornithological survey of a campinarana enclave in north-west Rondônia, southern Amazonian Brazil. The area was inventoried three times in 2010–12, totalling 899 net / hours and 110 hours of observations. A total of 171 bird species was identified, belonging to 44 families. Among them, at least nine species are closely associated with WSV: Green-tailed Goldenthroat Polytmus theresiae, White-fringed Antwren Formicivora grisea, Natterer's Slaty Antshrike Thamnophilus stictocephalus, Black Manakin Xenopipo atronitens, Plain-crested Elaenia Elaenia cristata, Pale-bellied Mourner Rhytipterna immunda, Campina Flycatcher Cnemotriccus fuscatus duidae, Plush-crested Jay Cyanocorax chrysops diesingii and Red-shouldered Tanager Tachyphonus phoenicius. Approximately 8% of the species recorded are migratory, most of them austral migrants. In addition, body mass and morphometrics of 136 individuals from 55 species are presented. Our results augment ornithological knowledge in Rondônia, aid our understanding of regional zoogeography, and serve as an alert to the need to preserve a region that has suffered severe anthropogenic impacts for >100 years.
Amazonia is the largest and most diverse biome on Earth (Mittermeier et al. 2003). It has the largest extent of continuous forest in the world and harbours impressive biodiversity (Kress et al. 1998, Mittermeier et al. 2003). The biome as a whole is very heterogeneous (Terborgh & Andresen 1998, ter Steege et al. 2003). It is a mosaic of different types of ecosystems resulting from variable regional edaphic and climatic conditions (Duivenvoorden et al. 2005, Haugaasen & Peres 2006, Fine & Kembel 2011, Fine et al. 2012). Among these ecosystems are several forest types, e.g., terra firme and várzea (Terborgh & Andresen 1998), as well as some non-forest environments, e.g. the enclaves or ‘islands' of open vegetation within forests (Anderson 1981, Fine et al. 2012, Fine & Bruna 2016, Mustin et al. 2017, Demarchi et al. 2018).
Enclaves of open vegetation are distributed discontinuously throughout Amazonia (Adeney et al. 2016). The origin of these enclaves is still being discussed—one hypothesis is a Pleistocene and Holocene provenance, when the climate in Amazonia became drier as a consequence of the last glacial maximum (Pessenda et al. 2001, Clark et al. 2009). The types of open vegetation in Amazonia are distinguished by their general physiognomy dictated by floristic composition according to the local edaphic, hydrological and climatic conditions (Adeney et al. 2016). The two main groups are savanna / cerrado (Sanaiotti et al. 1997, Silva et al. 1997, Sanaiotti & Cintra 2001, Aleixo & Poletto 2007, Aleixo et al. 2011, Boss & Silva 2014, Mustin et al. 2017) and a special type of vegetation that grows on white-sand soils, known in Brazil as campina and campinarana (Anderson 1981, Borges 2004, Borges et al. 2016a,b, Adeney et al. 2016). Recent ornithological studies of these ‘islands' of non-forest vegetation have revealed new taxa to science and helped to understand the zoogeography of the many patchily distributed species in Amazonia (Alvarez-Alonso & Whitney 2003, Whitney & Alvarez-Alonso 2005, Poletto & Aleixo 2009, Guilherme & Borges 2011, Alvarez-Alonso et al. 2013, Capurucho et al. 2013, Cohn-Haft et al. 2013, Whitney et al. 2013b,d, Borges et al. 2016a,b, Matos et al. 2016).
Rondônia state, in south-west Amazonian Brazil, lies within an area of endemism of the same name (Silva et al. 2005, Fernandes 2013). Although rich in endemic and / or rare species (Fernandes 2013), the state has already lost >30% of its forest cover due to logging and agroforestry (Serrão et al. 1996, Piontekowski et al. 2014, Fearnside 2017). Ornithological surveys in the state have progressively increased over the last 100 years (e.g. Hellmayr 1910, Stotz et al. 1997, Boçon 1999, Kirwan & Shirihai 2007, Olmos et al. 2011, Santos et al. 2011) and, as further areas are inventoried, several new species of birds have been discovered (Lanyon et al. 1990, Whitney et al. 2013a,b,c). Despite this, the richness of bird species and their distribution in the state as a whole are poorly known and have not been subject to major review. There are still numerous gaps in our ornithological knowledge of Rondônia because many areas are yet to be surveyed. Here, we present the results of a rapid inventory of an enclave of WSV near the BR-364 and the recently implemented Jirau hydroelectric power plant in north-west Rondônia.
Methods
Study area .—The study was undertaken in an enclave of WSV and its environs called Miratinga, located along a power transmission line west of the BR-364 (between Porto Velho and Abunã), c.30 km from Jaci Paraná in the municipality of Porto Velho, Rondônia (09°21′38.3″S, 64°39′29.2″W; Fig. 1).
Figure 1.
Location of the study area. TFF = terra firme forest, WSV = white-sand vegetation (campinarana), P = pasture. The black arrow indicates the commercial sand mining area. (Map adapted from Google Earth; satellite image courtesy of Google Inc. All rights reserved © 2018.)
Figure 2.
Overview of the white-sand vegetation (campinarana) survey area: (A) access road to campinarana, (B) panoramic view of the campinarana, (C) structure of the campinarana highlighting the presence of Mauritiella armata palms, (D) Pteridium sp. fern, (E) area where sand is being commercially mined.
Description of the area .—The campinarana enclave is mainly covered by dense shrubs, with sparse, small trees (2–5 m tall) (Fig. 2A–C) and some Astrocaryum acaule and Mauritiella armata palms (Fig. 2C). The soil is covered by grasses (Fig. 2A–B) and, as in other WSV environments, should be of low fertility and high acidity. At the edges of the patch, in areas of sparse vegetation and where the soil is more humid, an invasive fern Pteridium sp. is present (Fig. 2D). Part of the campinarana has been deforested and sand is being commercially removed (Fig. 2E). In the vicinity, there are small black-water streams and at least one medium-sized pond. During the wet season, puddles form where vegetation is sparse (Fig. 1) and in the campinarana, which is surrounded by fragments of terra firme forest severely modified by selective logging, and open pastures (Fig. 1).
Avifaunal sampling .—Three visits were made to the area in 2010–12. The avifaunal survey covered both the campinarana and surrounding fragments of terra firme forest and pastures (Fig. 1). Two approaches were used to inventory the area: (a) quantitative, using mist-nets and (b) qualitative, via field observations using binoculars. The campinarana was inventoried on 2 June 2010 (60 net / hours and two hours of observation), 26 February–3 March 2011 (439 net / hours and 54 hours of observation) and 20–24 August 2012 (400 net / hours and 54 hours of observation). Individuals captured with mist-nets were weighed using a Pesola® scale and their wing, tarsus and total lengths were taken with a millimetre ruler. Wing, tarsus and total lengths were measured in accordance with standard reference works, see Proctor & Lynch (1993: 295–297) and Sick (1997: 91, Fig. G). Ageing and sexing were performed whenever possible. Some specimens were collected as vouchers and were prepared using standard taxidermy techniques. Specimens were collected under ICMBio / SISBIO authorisation no. 23269-1, and deposited either at the Universidade Federal do Acre (UFAC), Rio Branco, or the Museu Paraense Emílio Goeldi (MPEG), Belém. Scientific nomenclature follows that of the Brazilian Committee of Ornithological Records (Piacentini et al. 2015).
Results and Discussion
A total of 171 species from 44 families was recorded in the campinarana enclave and its environs (Table 1). Of these, 74 (43.2%) species are non-Passeriformes and 97 (56.7%) Passeriformes. Among the latter, the families Tyrannidae (26), Thraupidae (17) and Thamnophilidae (12) were richest in species (Table 1). At least nine species recorded in the study area are closely associated with campinarana: Green-tailed Goldenthroat Polytmus theresiae, White-fringed Antwren Formicivora grisea, Natterer's Slaty Antshrike Thamnophilus stictocephalus, Black Manakin Xenopipo atronitens, Plain-crested Elaenia Elaenia cristata, Pale-bellied Mourner Rhytipterna immunda, Campina Flycatcher Cnemotriccus fuscatus duidae, Plush-crested Jay Cyanocorax chrysops diesingii and Red-shouldered Tanager Tachyphonus phoenicius (Table 1). Two other important records included Rondônia Bushbird Clytoctantes atrogularis (Guilherme & Souza 2013) and Buff-cheeked Tody-Flycatcher Poecilotriccus senex. Approximately 8% of the species recorded are visitors, mostly austral migrants, e.g. Large Elaenia Elaenia spectabilis, Chilean Elaenia E. chilensis, Small-billed Elaenia E. parvirostris, Fork-tailed Flycatcher Tyrannus savana, Crowned Slaty Flycatcher Griseotyrannus aurantioatrocristatus, Variegated Flycatcher Empidonomus varius, Southern Scrub Flycatcher Sublegatus modestus, Vermilion Flycatcher Pyrocephalus rubinus, Fuscous Flycatcher Cnemotriccus fuscatus bimaculatus, Chivi Vireo Vireo chivi, Creamy-bellied Thrush Turdus amaurochalinus, Yellow-bellied Seedeater Sporophila nigricollis and Double-collared Seedeater S. caerulescens, while Solitary Sandpiper Tringa solitaria was the only Nearctic migrant (Table 1).
Species accounts
GREEN-TAILED GOLDENTHROAT Polytmus theresiae
Relatively common but discontinuously distributed in enclaves of open vegetation throughout Amazonia (Schuchmann 1999, Borges et al. 2001, Sanaiotti & Cintra 2001, Aleixo & Poletto 2007, Schulenberg et al. 2007, Guilherme 2012). Hellmayr (1910) reported two collected by W. Hoffmanns around Rio Preto, in the north-east of the state, and Aleixo & Poletto (2007) the presence at MPEG of one collected by J. Hidasi at Guajará-Mirim, on the border with Bolivia. Additionally, the species was photographed in the municipalities of Cabixi and Vilhena in southern Rondônia (Wikiaves 2018). On 2 June 2010, three were collected (MPEG 70938, 70939, male, 70940) and on 22–23 August 2012 we collected another five (UFAC 507, 508, 511, 522, 523). Available records of P. theresiae in Rondônia indicate that the species is locally common, but only in enclaves of cerrado, campina and campinarana.
NATTERER'S SLATY ANTSHRIKE Thamnophilus stictocephalus
Previously treated as a race of a widespread Eastern Slaty Antshrike T. punctatus (Isler et al. 1997). Distributed patchily in campina and campinarana east of the Guaporé / Madeira Rivers to the island of Marajó in Pará (Isler et al. 1997, Zimmer & Isler 2003). Olmos et al. (2011) reported T. stictocephalus in savannas at Serra da Cutia National Park, in the south-west of the state, and at Campos do Urupa within the Uru-Eu-Wau-Wau Indigenous Territory, in central Rondônia. Natterer's Slaty-Antshrike has been found in several municipalities along the BR-364, between Vilhena and Porto Velho (Wikiaves 2018). Very common in the study area, being seen and caught in mist-nets daily (Fig. 3A). Five specimens were collected, a female on 2 June 2010 (MPEG 70950) and two pairs, on 27 February 2011 (UFAC 284, 286) and 1 March 2011 (UFAC 310, 309). Our records of T. stictocephalus extend the species' range to extreme north-west Rondônia.
TABLE 1
Birds recorded in a campinarana (white-sand vegetation) and its environs in north-west Rondônia, Brazil. Habitat: C = campinarana; TF = terra firme forest; R = reservoirs and lakes; AO = open areas; P = pasture and man-modified areas. Record types: V = vocalisation; O = sight; S = museum specimen. Nomenclature follows Piacentini et al. (2015). 1 = follows Handbook of the birds of the world (del Hoyo & Collar 2016). * = white-sand specialists following Stotz et al. (1996) and Borges et al. (2015). ** = migrants a = austral; n = Nearctic.
Continued
Continued
Continued
Continued
RONDÔNIA BUSHBIRD Clytoctantes atrogularis
A globally threatened species (BirdLife International 2017) whose unusual record in the study area was discussed by Guilherme & Santos (2013). The female collected (UFAC 473) represents the westernmost available record (Costa et al. 2017).
WHITE-FRINGED ANTWREN Formicivora grisea
Occurs from the right bank of the Madeira River east to the Atlantic coast, including all of north-east Brazil, as well as in northern South America including the Guianas, Venezuela and Colombia (Zimmer & Isler 2003). Recently found in campinarana in extreme south-west Amazonas (Guajará) and westernmost Acre (Cruzeiro do Sul and Mâncio Lima) (Poletto & Aleixo 2005, Guilherme 2012). In Rondônia, it was known from around Rio Preto in the north-east (Hellmayr 1910) and in savanna at Traçadal Biological Reserve and Serra da Cutia National Park (Olmos et al. 2011) in the centre-west. Abundant in campinarana at Miratinga. On 2 June 2010, three were collected (MPEG 70951, male, 70952, female, 70953, male). On 27–28 February 2011, four were trapped of which three were collected (UFAC 283, male, 288, female, 304, female) and on 20–23 August 2012 seven were trapped of which four were prepared as specimens (UFAC 476, juvenile male, 480, male, 510, female, 525, male). Records of F. grisea at Miratinga extend the species' range in Rondônia 232 km to the north-west and 227 km north, from Rio Preto and Traçadal Biological Reserve, respectively.
BLACK MANAKIN Xenopipo atronitens
Considered an indicator species of campinarana (Borges et al. 2016a). Although abundant in habitat, it is patchily distributed (Aleixo & Poletto 2007, Poletto & Aleixo 2005, Guilherme & Borges 2011, Borges et al. 2014, 2016b). Previous records in Rondônia were by Whittaker (2004) at Taquaras (BR-425) and by Olmos et al. (2011) in savanna at Traçadal Biological Reserve and Serra da Cutia National Park. Since 2010, it has been photographed in several municipalities in eastern Rondônia, e.g. Machadinho d'Oeste, Parecis and Chupinguaia (Wikiaves 2018). At Miratinga, Black Manakin was seen and trapped daily. A male was collected on 6 February 2010 (MPEG 70977), while another four were collected subsequently, three in 2011 on 26 February (UFAC 276, female, 282, male) and 1 March (AC 312, female), and one on 22 August 2012 (UFAC 512, male). Records of X. atronitens at Miratinga extend its range to far north-west Rondônia.
BUFF-CHEEKED TODY-FLYCATCHER Poecilotriccus senex
Until very recently, known only from the type locality at Borba, Amazonas state, on the right bank of the lower Madeira River (Hellmayr 1910, Hoyo et al. 2004). In recent years, recorded at localities on the right bank of the middle (Cohn-Haft et al. 2007, Whittaker 2009) and upper Madeira (Whittaker 2004, Wikiaves 2018). In Rondônia, reported initially in 2002, at a campina at Taquaras (BR-425), in the north-west of the state (Whittaker 2004). On 27 February 2011, we collected one at the edge of campinarana (MPEG 74005). Unfortunately, during its preparation, mass was not taken and neither was it possible to sex the bird (Fig. 3B; Table 2). Recent records indicate that the species inhabits patches of open vegetation in a swath from northern Rondônia and extreme south-east Amazonas (e.g. Humaitá National Forest) from the right bank of the Madeira east to the Madeira / Tapajós interfluvium (Whittaker 2004, 2009, Cohn-Haft et al. 2007, Wikiaves 2018).
Figure 3.
Bird specialists of white-sand vegetation in Amazonia: (A) male Natterer's Slaty-Antshrike Thamnophilus stictocephalus, 27 February 2011, (B) Pale-bellied Mourner Rhytipterna immunda, 28 February 2011, (C) Buff-cheeked Tody-Flycatcher Poecilotriccus senex, 27 February 2011, (D) Plush-crested Jay Cyanocorax chrysops diesingii, 1 March 2011 (Edson Guilherme)
PALE-BELLIED MOURNER Rhytipterna immunda (Figure 3C)
An uncommon species readily confused with a Myiarchus (Lanyon 1973). R. immunda is unique to savanna environments in Amazonia, from easternmost Colombia to the Guianas, and in Brazil it occurs patchily in WSV through the Negro drainage east to Pará, Amapá and Tocantins, and in southern Rondônia and Mato Grosso (Lanyon 1973, Scholes 2004, Whittaker 2004, Dornas et al. 2012). It has also been recorded in north-east Bolivia (Scholes 2004, Tobias & Seddon 2007). The first record in Rondônia was documented by Whittaker (2004) in the north-west of the state, in a campina at Taquaras, Porto Velho municipality. Subsequently, it was recorded in savanna at Serra da Cutia National Park, south-west Rondônia, and in Uru-Eu-Wau-Wau Indigenous Territory, in central Rondônia (Olmos et al. 2011). Also documented in the municipalities of Guajará-Mirim and Machadinho d'Oeste (Wikiaves 2018). Among species associated with campinarana, this was one of the mos abundant in mist-nets. Ten were trapped, of which five were collected: three on 26 and 28 February 2011 (UFAC 278, 295, 296) and two on 22 August 2012 (MPEG 82235–36). Records of R. immunda in north-west Rondônia (e.g. Miratinga) are the south-westernmost in Brazil.
CAMPINA FLYCATCHER Cnemotriccus fuscatus duidae
Strongly associated with campina / campinarana (Borges et al. 2016a). Differs from other races of C. fuscatus by its much more yellowish underparts (Zimmer 1938; Fig. 4A). It occurs patchily across almost all of Amazonia (Tobias & Seddon 2007, Guilherme & Borges 2011, Borges et al. 2016a). One was collected on 22 February 2011 in campinarana (UFAC 294; Fig. 4A–B), the first record of this taxon in Rondônia. The closest previous record of C. f. duidae was on the Bolivia / Brazil border at Piedritas, on the left bank of the Madeira River, c.100 km south-west of our study area (Tobias & Seddon 2007). C. f. duidae, unlike its congeners (see below), appears to be resident in campina / campinarana in the region.
FUSCOUS FLYCATCHER Cnemotriccus fuscatus
In addition to the specimen attributed to C. f. duidae (above), three other specimens of C. fuscatus were collected. Two (MPEG 70971 and UFAC 509) match C. f. beniensis and a third (UFAC 477) more closely resembles C. f. bimaculatus (Fig. 4A–C). Although Tobias & Seddon (2007) argued that C. f. beniensis could be synonymous with C. f. fuscatior, a series collected in Acre (Guilherme 2009, 2012, 2016) plus the two from Rondônia agree with the description presented by Gyldenstolpe (1945) to differentiate it from C. f. bimaculatus. Some of the differences noted by Gyldenstolpe (1945) and observed in UFAC 509 are: ‘…chin and throat grayish-white, usually without any yellowish tinge; breast greyish brown without olivaceous suffusion; bill larger and stronger…' (Fig. 4A–C). Although bill length is almost identical among specimens UFAC 509 (beniensis) and 477 (bimaculatus) (14.1 vs. 14.04 mm respectively), in UFAC 509 it is broader (5.0 vs. 3.92 mm) and flatter than in UFAC 477 (Fig. 4C). The morphological similarities, as a whole, between UFAC 509 from Rondônia (Fig. 4A–C) and the holotype of C. f. beniensis, from Bolivia, were proven by comparing it with the photograph of the type specimen (NRM 569425) online ( http://www.nrm.se). UFAC 509 also shows clear differences from the holotype of C. f. fuscatior (Fig. 4D). The latter, AMNH 211013 from Ecuador, as described by Chapman (1926) has ‘…Upperparts much darker and wing-bars narrower than in any other described race of the species… the breast grayish olive, the belly pale sulphur-yellow…' (Fig. 4D). In UFAC 509, the wingbars are broad as in UFAC 477 (bimaculatus) (Fig. 4B) and the back and chest are brown (Fig. 4A–B), not grey as in C. f. fuscatior (Fig. 4D). Additionally, C. f. fuscatior is associated with várzea and river islands (Tobias & Seddon 2007), while UFAC 509 (Fig. 4A–C) and MPEG 70971 are from a campinarana enclave in terra firme, which reinforces our conviction that the two latter specimens represent beniensis. Taxonomy of the group is confused (Chapman 1926, Zimmer 1938, Gyldenstolpe 1945, Tobias & Seddon 2007) and genetic and vocal analyses should seek to clarify how many species-level taxa are involved. The certainty is that at least three taxa of the C. fuscatus complex occur at Miratinga. This is the first record of beniensis in Rondônia (where its status is uncertain), while bimaculatus is an austral migrant (Hellmayr 1910, Stotz et al. 1997, Whittaker 2004, Santos et al. 2011).
PLUSH-CRESTED JAY Cyanocorax chrysops diesingii
This subspecies is the Amazonian substitute of C. c. chrysops, which is common in southeast Brazil, northern Argentina, Uruguay, Paraguay and Bolivia (Ridgely & Tudor 1994). C. c. diesingii is a specialist of campina / campinarana (Aleixo & Poletto 2007, Whittaker 2009, Borges et al. 2016a). On 1 March 2011 a pair was observed vocalising and later one was photographed at the edge of campinarana at Miratinga (Fig. 3D). In 2012, the species was seen daily in the same place. This taxon appears to be common in enclaves of campinarana along the BR-364 between Porto Velho and Abunã, in the north-west of the state. It is possible that C. c. diesingii occurs sympatrically with the recently discovered Campina Jay C. hafferi (Cohn-Haft et al. 2013) in campina / campinarana further north, in Amazonas, e.g. in WSV enclaves around Borba (Hellmayr 1910, Wikiaves 2018).
Figure 4.
Three specimens of the Fuscous Flycatcher Cnemotriccus fuscatus complex collected in campinarana and deposited at the Universidade Federal do Acre, Rio Branco (UFAC) compared to the holotype of C. f. fuscatior in the American Museum of Natural History, New York (AMNH 211013): (A–B) ventral and lateral views of UFAC 509, 477 and 294; (C) front view showing difference between bills of UFAC 477 and UFAC 509 (Edson Guilherme); (D) ventral and lateral views of AMNH 211013 (Paul Sweet). UFAC 294 = C. f. duidae; UFAC 477 = C. f. bimaculatus, UFAC 509 = C. f. beniensis and AMNH 211013 = C. f. fuscatior holotype.
RED-SHOULDERED TANAGER Tachyphonus phoenicius
Typical of open vegetation in Amazonia (e.g. cerrado, campina and campinarana) and present in three different biogeographic regions. North of the Solimões / Amazon River in the states of Roraima, Pará and Amapá, as well as in eastern Colombia, southern Venezuela and the Guianas; in the south, from the Madeira basin in the region of Guayaramerin in Bolivia (Tobias & Seddon 2007) to the east; and in the extreme south-west, in northeast Peru (Loreto), western Acre (Mâncio Lima and Cruzeiro do Sul) and south-western Amazonas (municipality of Guajará) (Hilty 2011, Guilherme 2012, 2016; E. Guilherme & A. Aleixo unpubl.). In Rondônia, T. phoenicius was recorded by Olmos et al. (2011) at Traçadal Biological Reserve and Serra da Cutia National Park, in the south-west of the state, with other documented records from the municipalities of Parecis and Vilhena (Naumburg 1930, Wikiaves 2018). A female was collected in campinarana at our study site on 20 August 2012 (UFAC 475), extending the species' range in Rondônia to the north, c.230 km from Traçadal Biological Reserve.
Discussion
Although our visits to the study site were short, totalling just nine days, a significant number of species was recorded. The avifauna found exclusively in campinarana represented 17.7% of all species recorded and consists of birds that colonise forest edge, open country or habitat specialists (sensu Stotz et al. 1996, Borges 2004, Borges et al. 2016a). Of the 35 taxa considered by Borges et al. (2016a) to be WSV specialists throughout Amazonia, 17.1% were recorded in this small campinarana. However, if we consider only the 11 WSV specialists from the southern Solimões / Amazon basin (sensu Stotz et al. 1996), representativeness increases to 54.5%. Some species (e.g. Xenopipo atronitens) have specialised to such an extent that they occur only in enclaves of open vegetation across Amazonia (Capurucho et al. 2013, Borges et al. 2016a). This implies that vegetation growing on white sand functions as ‘islands' or mini-refugia (sensu Isler et al. 1997) within the surrounding forest. These ‘islands' also offer a range of food resources capable of attracting seasonal migrants from other open biomes (e.g., Cerrado, Chaco, campos sulinos), which explains the comparatively large number of austral migrant species in this small patch of WSV. The result is a unique community of birds different from that in surrounding forest (Borges 2004). Therefore, the presence of an enclave of campinarana contributes significantly to regional diversity in Amazonia (Borges et al. 2016a).
Body mass and morphometrics .—These data, taken from 136 individuals of 55 different species (Table 2), are presented separately by age and gender (Table 2). Because many species in the study area are uncommon and patchily distributed, we consider it important to publish these mass and morphometric data. Such information forms the basis of comparative studies in various aspects of animal biology, including community structure and theoretical modelling (Hudson et al. 2013, Frasier 2016). Dunning (2008) compiled body mass data for 8,700 species worldwide, but for some the number of individuals sampled was very small and from a single locality, e.g. Thamnophilus stictocephalus, for which just one male from Bolivia was available to Dunning (2008). In this study, we not only increased the number of T. stictocephalus so measured, but we also collected mass and morphometrics for many other species from Brazil that were poorly sampled or unrepresented in Dunning's work, e.g. Rondônia Warbling Antbird Hypocnemis ochrogyna, which was recently split from H. cantator (Isler et al. 2007; Table 2).
Conservation .—The small enclave of WSV at Miratinga lies within a region that is highly threatened (Vale et al. 2008, Fernandes et al. 2010). It is directly impacted by the BR-364 and, according to the Socioecological and Economic Zoning of Rondônia, forms part of 1.2 Sub-zone, which is subject to accelerated occupation and uncontrolled deforestation. Furthermore, the area is likely to witness increasing agricultural and other anthropogenic disturbance in the future (Fernandes et al. 2010). A concrete example of this is the recently implanted Jirau Hydroelectric Plant, 9.5 km from the study site. Allied to this, an energy transmission line, linking the states of Rondônia and Acre, transects the campinarana (see Fig. 4 in Guilherme & Santos 2013) affecting also adjacent terra firme forests. Furthermore, commercial sand mining has directly impacted this small ‘island' of WSV in north-west Rondônia. This process completely destroys the vegetation, thereby exposing the soil (Ferreira et al. 2013, Adeney et al. 2016). Post-exploration, the mined areas are usually abandoned without any type of environmental recovery (Ferreira et al. 2013; Fig. 2E). Finally, human impacts on this area date back many decades. One evidence of this is the Madeira / Mamoré railway, whose scar, 52 years after its decommissioning, is still visible in the centre of the study site (Fig. 1).
TABLE 2
Body mass and morphometrics of 55 different species captured in a campinarana and its environs in north-west Rondônia, Brazil. Age: A= adult; Y = young. Sex: F = female; M = male, U = undetermined. Nomenclature follows Piacentini et al. (2015). Wing, tarsus and total length in mm; body mass in g. * No mass data from South America in Dunning (2008). ** No mass data from Brazil in Dunning (2008).1 Sample of fewer than ten individuals in Dunning (2008). 2 No mass data in Dunning (2008).
Continued
Continued
Although small and degraded, the patch of campinarana we surveyed still harbours many species of conservation concern (Table 1, Guilherme & Santos 2013). In general, patches of WSV in Amazonia are fragile and sensitive to anthropogenic activities, being both threatened and poorly represented within the protected area system (Adeney et al. 2016, Fine & Bruna 2016). Despite an increase in studies of these ecosystems in recent years, many remain largely unknown scientifically (Adeney et al. 2016, Fine & Bruna 2016). We recommend that the environmental authorities in Brazil aim to restore the environmental integrity of the site, and consider the possibility of incorporating our study area into a conservation unit.
Acknowledgements
We thank Francislaine Paulino for inviting us to monitor avifauna along the Porto Velho–Rio Branco powerline. CEPEMAR (Serviços de Consultoria em Meio Ambiente Ltda.) provided financial and logistical support. We also thank the team responsible for the ornithological collection of the Museu Paraense Emílio Goeldi, Belém, especially its curator, Dr Alexandre Aleixo, as well as Maria de Fátima Cunha Lima, Romina Batista and Sidnei de Melo Dantas for their support during this study. Paul Sweet of the American Museum of Natural History, New York, kindly photographed the holotype of C. f. fuscatior. Dr Evandro Ferreira (INPA) identified the two palm species in the study area via photographs. EG is grateful to CNPq for its support via project no. 474592/2010-3 (2010-2012). Specimen collection was authorised by the Chico Mendes Biodiversity Conservation Institute (ICMBio) of the Brazilian Ministry of the Environment, via SISBIO license no. 23269-1.
