An annotated checklist of the birds of the upper Siang region , Arunachal Pradesh , India

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for floral and faunal diversity in Arunachal Pradesh.The river Tsangpo enters India in the north from Tibet (China) to become the Siang and cuts deep through the mountains to emerge as the primary tributary of the Brahmaputra.This valley attains a unique character as the river carves through the snow-laden mountain ranges to depths as low as 300m), 'carrying' wet tropical conditions very close to the northern mountain ranges (Birand & Pawar 2004).
The earliest bird records for these areas were restricted to the lower reaches of the valley closer to the plains of Assam, due to lack of access (Baker 1913;Stevens 1915;Ludlow & Kinnear 1944).The first comprehensive avian survey that included the upper Siang Valley was by Katti et al. (1992) who identified 116 species for this region.The biodiversity potential of Arunachal Pradesh was becoming more apparent when a review by Singh (1994) reported 519 species for the state of Arunachal Pradesh at a time when detailed surveys had hardly been conducted in most areas.Bird surveys in Arunachal Pradesh have tended to concentrate on its western (Pakke Tiger Reserve, Eaglenest Wildlife Sanctuary) and eastern (Namdapha National Park) borders due to easier access, and had neglected the north-central regions of the Siang and the Dibang valley except for rare surveys by Salim Ali (Ali & Ripley 1948).Subsequent surveys by Sen & Mukhopadhyay (1999), Singh in Haridasan et al. (1999), Birand & Pawar (2004), Naoroji & Sangha (2006), Choudhury (2010) and Mize et al. (2014) has helped in presenting the remarkable diversity of species that are found in this area.Most of these surveys, however, have had the disadvantage of working within a short period of dry weather in the winter, which provides only a limited picture of the seasonal migrants.The current survey is the most comprehensive list of birds for this area with numerous species that have not been reported earlier.

Materials and Methods
Field surveys were conducted primarily in the district of Upper Siang in the Indian state of Arunachal Pradesh, which is inhabited by people belonging to the Adi tribe (Fig. 1; Image 1).A few observations were made along the road which largely follows the Siang River between Pasighat in the plains to Upper Siang while passing through areas of East Siang District.While the majority of the fieldwork was conducted in the study village of Bomdo, various other villages and locations in the district were visited at different times.Towards the northeastern part of the district, the remote Yangsang River valley was visited on three separate occasions.The other prominent areas visited included the villages of Ramsing, Karko, Shimong, Jengging and Yingkiong to the south and Gelling, Tuting, Migging and Janbo to the north (Fig. 2).Except for the study village of Bomdo, information on birds in all other areas was based on opportunistic encounters.
Records of bird presence were obtained over repeated visits from 2010 to 2016 between the months of November to May.Unlike previous surveys in this area which lasted from 20 days to a month, we spent a minimum of six months during the survey years in this landscape.Except for Chettri et al. (2006) who were surveying for raptors, no other study in the region went beyond the month of April.Detections were based on visual identification, calls, and identification of dead birds hunted by locals.Fieldwork consisted of walks along established trails and roads across a range of habitats such as primary and secondary forests, agricultural areas, riverine areas, plantations, etc. Point counts were conducted in the first year at the primary study village and all subsequent sightings were based on opportunistic detections.Walks would typically be conducted early in the morning and end only around late afternoon.
The survey areas ranged from 300m near the Siang to ~2000m in some of the villages located in the Yangsang River valley.It has to be emphasized that the surveys were conducted entirely in communitymanaged lands outside protected areas.This consisted of old growth forests and a matrix of shifting cultivation fields and fallows, secondary forests and plantations.It bears mentioning here that the survey locations in the Yangsang River valley were all located on the left bank of the Siang River while all other survey locations in the Adi area were located on the right bank.The locations of species relative to the Siang River has been provided in the species table.
We have referred to Praveen et al. (2016) as the taxonomic basis for the nomenclature of the species that we have reported here.For identification of birds in the field, we used Kazmierczak & Perlo (2008), Grimmett et  2016) and Robson (2000).Calls were cross-checked against the online database at http://www.xeno-canto.org/.

Results
A total of 252 species was identified for this region (Images 2-18).While the majority of identifications were done through field surveys based on sightings and calls, a few species were identified from dead specimens that had been killed by local hunters.Among the species recorded, five species (3 Vulnerable, 1 Endangered and 1 Near Threatened) are included in the IUCN Red List of Globally Threatened Bird Species (IUCN 2017).Birds belonged to 63 families and 17 orders with 66 species being reported for the first time from this region (IUCN 2017).We recorded nine species of cuckoos from this region, none of which had been recorded earlier.We also recorded the presence of migrating waterfowl such as Greylag Goose Anser anser and Mallard Anas platyrhynchos which have not been reported earlier from the Siang Valley.The most common families in this region were Muscicapidae (27 species), Leiothrecidae (22), Accipitridae (13 species) and Cuculidae (10 species).Detailed accounts are provided for 16 species and two species groups below.We chose to group similar species into the two species groups because they are all new and important records for this area and have been a prominent absence from existing studies till date.The other species described below are either new records, rare and unusual sightings for the region or globally threatened species.

Accounts of species of interest
Migrant Waterfowl (Northern Pintail, Greylag Goose, Common Teal, Mallard, Little Grebe): Various migratory waterfowl were recorded for the first time for this region.While the Little Grebe Tachybaptus ruficollis has been reported earlier by Naoroji & Sangha (2006) around Gelling, it was again seen in that same area in a small pond in the village of Norbuling below Gelling.A flock of 18-20 Northern Pintail Anas acuta were seen swimming in the Siang River below Bomdo in October 2015.They appeared to be floating down the river together.Five Greylag Geese Anser anser, three Common Teal Anas crecca and two Mallards Anas platyrhynchos were seen in a small pond in the village of Payengdam in the Yangsang Valley in March 2014.None of these species have been reported from this region earlier.
Barn Owl (Tyto alba Scopoli, 1769): A stray bird was found close to Bomdo Village by a villager who caught and photographed it in September (2014).It was identified from the photograph later.There is no other record for this species from this region and even villagers claimed to have never seen it before.
Cuckoos: Nine species of cuckoos were recorded in the landscape, none of which had been reported earlier.Dark-sided Thrush (Zoothera marginata Blyth, 1847): Unrecorded in this region earlier.A very shy and silent bird was seen (December 2013) in thick undergrowth beside a small stream in mature forest at ~600m.The individual was observed foraging in the shallow stream, probably for insects or molluscs.Good quality pictures allowed us to distinguish this species from the similar Long-billed thrush through the presence of rufous-brown upperparts and wing panel, strongly patterned sides of head, white eye-ring, contrasting patches on ear coverts and pale crescent behind ear coverts.
Long-tailed Thrush (Zoothera dixoni Seebohm, 1881): Identified from a dead specimen trapped by a villager in steep secondary forest close to a terrace cultivation plot below Bomdo Village.
Black-throated Thrush (Turdus atrogularis Pallas, 1776): Sighted near Payengdam Village at 1,500m in the Yangsang Valley in early March.Reported earlier from the Mouling area by Pratap Singh in Haridasan et al. (1999) as the previously recognised Dark-throated Thrush which included both the Red-throated and Blackthroated Thrush species.
Blyth's Tragopan (Tragopan blythii Jerdon, 1870): Identification was made based on the skin of an individual brought back by hunters from mature forest near the Mouling National Park.Reported to be largely absent around villages and agriculture but not uncommon in mature forests ~2,000m far from villages.The individual belonged to the subspecies Tragopan blythii molesworthi and was consistent with existing knowledge of the distribution of this subspecies being restricted to the north of the Brahmaputra.
Beautiful Nuthatch (Sitta formosa Blyth, 1843): Occasional sightings in winter always among mature forests.Usually seen as part of mixed flocks consisting of Chestnut bellied Nuthatch Sitta castanea, Cutia Cutia nipalensis and Lesser Racket-tailed Drongo Dicrurus remifer.This species is also classified as 'Vulnerable' in the IUCN Red List and has been reported earlier by other surveys from this area.
Black-headed Shrike Babbler (Pteruthius rufiventer Blyth, 1842): Two individuals sighted in February 2015 once in mature oak forest above 1,500m in a mixed flock consisting of Cutia and an unidentified Nuthatch close to Mouling National Park.Reported only once earlier by Sangha & Naoroji (2007)

Discussion
This is the longest faunal study for this region and provides the most comprehensive list of avian species for the Siang Valley.Sampling for this study took place across the seasons, unlike previous studies which were restricted to the dry, cold months.This temporal spread in sampling allowed us to record species which were present only during the warmer months such as cuckoos and migrant waterfowl which have never been recorded earlier for this region.
Rivers have been known to affect dispersal and consequently species distributions due to their deep gorges dissecting mountain ranges and/or their broad drainage basins that are seasonally inundated especially for sub-continental avifauna (Ripley & Beehler 1990;Ramachandran et al. 2017).Sister-species pairs occur across river barriers and populations of a species across such barriers have also been known to diversify over time (Burney & Brumfield 2009).Biogeographically, the Brahmaputra is one such barrier (Dalvi 2012), and the records of species in this study from the north and south bank of the Siang are consistent with the known distribution of species with reference to the Siang, Dibang, major tributaries of the Brahmaputra.
There remain drawbacks even in this study as we were unable to sample at higher altitude areas (>2,500m) and more extensively in primary forest areas.Intensive sampling of all the representative habitats should add substantially to this list.
The study, which was conducted entirely in community managed forests and mixed-use landscapes outside protected areas demonstrates the high biodiversity value of such landscapes.Recent studies from other parts of northeastern India also highlights the importance of Jhum (shifting cultivation) landscapes for bird communities, especially in view of large scale shifts to monoculture plantations (Mandal & Raman 2016).
The discovery of migrant waterfowl using the Siang River as a migratory route is a significant finding.The Siang Valley remains poorly represented in terms of IBA locations, with Mouling National Park being the only area for this region (ENVIS 2016).Our sighting of an unidentified crane flying over the Siang suggests that the Siang may also be used as a migratory route by cranes as shown by Choudhury (1994) for Common Cranes Grus grus in the Dibang River.We believe the current study provides adequate evidence for further investigation and designation of additional IBA sites for the upper Siang region.
The upper Siang region has been experiencing unprecedented changes in recent decades.Road and other infrastructure development, illegal timber felling and increase in acreage of cash crops have led to degradation and loss of habitat.Proposed hydroelectric projects on the Siang River further threaten to irreversibly alter the fragile ecology of the region.A comprehensive documentation of the avifauna for this region is necessary to counter these developmental threats.We believe such documentation can emerge only from focused surveys across seasons that are able to cover even the remote parts of this region.

Figure 1 .
Figure 1.Map showing the location of Upper Siang District (in red) within the northeast Indian state of Arunachal Pradesh.Inset map shows the location of the state of Arunachal Pradesh within India.

Figure 2 .
Figure 2. Map showing the locations of various survey sites within the district of Upper Siang.Survey sites are the names of villages but sampling included areas between two adjacent villages as well.The base layer satellite imagery is sourced from the freely available 'World Imagery' tiles provided by www.arcgis.com.

Rufous-necked Hornbill (Aceros nipalensis Hodgson
, 1829): A dead pair was brought back by village hunters from mature forest near Mouling National Park in December 2009.Only one previous report of this species by Katti et al. from 1992.This species is classified as 'Vulnerable' in the IUCN Red List of Threatened Species.Wallcreeper (Tichodroma muraria Linnaeus, 1866): An extended sighting of individual in non-breeding plumage in January 2012 on a steep rock face abutting the Siang River at ~450m below Bomdo Village.Another individual was seen in November 2015 close to Pangin in East Siang at around 380m.Both sightings were of solitary birds, relatively unafraid of human presence.Chestnut Thrush (Turdus rubrocanus Hodgson, 1846): Seen in areas above 1,500m in the Yangsang Valley in early March 2014.Fairly common at that altitude in Rhododendron bushes and secondary forests.
from a much lower altitude.