Avifauna of four protected areas of Terai-Arc Landscape, India: significant records and a checklist of species

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INTRODUCTION
The Terai-Arc landscape is a part of the Terai-Duar Savanna Eco-region, between River Bagmati (Nepal) to the Yamuna (India) spreading over an area of 30,000 km 2 .In India, the region runs parallel to the foothills of the Himalayas encompassing the Shivalik hills, the Bhabar tract, and the Terai plains (Rodgers & Panwar 1988).Once covered with a continuous mosaic of dense forest and tall grassland, the natural vegetation of the region today exists amid human habitation and agricultural land (Johnsingh et al. 2004).The natural vegetation is being conserved and managed under four national parks (NP): Rajaji NP, Corbett NP, Dudhwa NP, and Valmiki NP, along with five wildlife sanctuaries (WS): Sonanadi WS, Kishanpur WS, Katerniaghat WS, Suhelwa WS, and Sohagibarwa WS, which sustain birds and mammals representing Himalayan and Gangetic plain affinities along with many species of national and international importance (Rahmani et al. 1989;Pandey et al. 1994;Chanchani et al. 2014).
Protected areas (PAs) of the Terai-Arc landscape have been explored relatively less as far as bird communities are concerned.Previous research on avifauna was either to assess community structure and status of particular groups or species and has been restricted to limited PAs of this landscape.Pandey et al. (1994) assessed the bird community structure of Rajaji NP.Dhakate et al. (2008) and Kidwai et al. (2013) highlighted the status of water birds and terrestrial birds of Corbett NP respectively.Rahmani et al. (1989) and Javed et al. (1999) determine the status of Bengal Florican Houbaropsis bengalensis and Swamp Francolin Francolinus gularis, respectively, in Dudhwa NP.Maheswaran & Rahmani (2005) studied the breeding biology of Black-necked Stork Ephippiorhynchus asiaticus in Dudhwa NP.Kalam (2005) and Sethy & Chauhan (2011) conducted studies to look at avian diversity in Katerniaghat WS.Very few ornithological studies have been carried out in the Valmiki Tiger Reserve (TR) (Sinha 2012;Choudhury 2016).Hence avifaunal composition of many PAs of the Terai-Arc landscape is not known hitherto and it is therefore desirable to understand the avifaunal composition to bridge the knowledge gap.

STUDY AREA
Avifaunal surveys were carried out in Pilibhit TR and Valmiki TR, and Katerniaghat WS, and Udaipur WS.These PAs are situated on the Indo-Nepal border in Uttar Pradesh and Bihar (Figure 1).
Katerniaghat WS (KWS) (27.916-28.416 °N, 81.000-81.416°E) covers an area of 400.09 km 2 and is located in the Upper Gangetic plain in the Terai of Bahraich district, Uttar Pradesh, India (Figure 1).KWS was declared as a wildlife sanctuary in 1976.It is connected with Bardia NP in Nepal via the Khata corridor.The Girwa (Karnali) river and a major canal flow through this sanctuary, which is a part of the Dudhwa TR.Other areas of the sanctuary are disturbed because the narrow forest is bisected by a railway line and several roads.The major forest types found here are northern moist deciduous sal forest, northern dry plain sal forest, northern tropical dry deciduous sal forest, tropical seasonal swamp forest, low alluvial savannah, and moist sal savannah forests (WWF-India 2007).
Pilibhit Tiger Reserve (PTR) (28.866-28.767°N, 79.916-82.250°E) is spread over an area of 730.24 km 2 and is located in Pilibhit District of Uttar Pradesh, India.It is connected with the Terai-Bhabar forests of the Surai range of Terai East forest division in Uttarakhand in the north-west, Kishanpur WS in the south-east and Shuklaphanta NP in Nepal in the north.PTR supports a mosaic of dry and moist deciduous, scrub savannah and alluvial grasslands (Anwar et al. 2010).
Valmiki Tiger Reserve (VTR) (area 901.2 km 2 , 27. 167-27.50 °N, 83.833-84.167 °E) is located in the West Champaran district of Bihar in the eastern part of Terai-Arc landscape and the west by the Gandak River.It is contiguous with Nepal's Chitwan NP in the north, sharing a boundary of ~100 km along which is forested habitat.VTR's elevation ranges between 140 m and 874 m.Vegetation is represented by the bhabar dun sal forest, dry Shivalik sal forest, western Gangetic moist mixed deciduous forest, Khair-sissoo forest, cane brakes, eastern wet alluvial grassland, and Barringtonia swamp forest (Champion & Seth 1968;Maurya & Borah 2013) which makes it one of the 16 important bird area (IBA) in Bihar (Rahmani et al. 2016).
Udaipur Wildlife Sanctuary (UWS) (26.778-26.820 °N, 84.406-84.454 °E) encompassing an area of 887.35 ha of forest land is situated in the West Champaran district of Bihar, 50-60 km south to VTR.The unique feature of UWS is its being a forested wetland.The sanctuary has 'Saraiyaman Lake', an IBA (Rahmani et al. 2016).The vegetation is represented by mixed deciduous forest, riverine forest dominated by Syzygium cumini, plantation, grasslands, and aquatic vegetation.

METHODS
Birds were recorded traversing trail and road transects in PTR (between March and May 2014, February and May 2015); and KWS (during 2001-2004, 2006, 2008, and 2015) (MacKinnon & Phillips 1993).In VTR, birds were recorded randomly during camera traps exercises and while travelling within the forests between 2014 and 2017.Birds of UWS were surveyed between 17 and 19 February 2018 for terrestrial birds (MacKinnon & Phillips 1993) and the total count method for water birds.Species photo-captured in camera traps (used for tiger census) were also included to compile the species list of each protected area.
MacKinnon's species richness was used for terrestrial species enumeration.One km long linear transects were laid in/along various habitats viz.woodland (sal, salmixed, moist riverine, dry riverine, teak plantation), water body (river and streams), grassland, barren land, and scrubland.On each transect, a list of 20 different species in KWS, PTR, and VTR, while a list of 15 species in UWS was generated traversing slowly at a speed of 0.5 km/hr.Once a list was completed, another list was prepared.No species was recorded more than once in each list.A total of 266 lists in KWS, 108 lists in PTR, 58 lists in VTR, and 18 lists in UWS were prepared.Birds were surveyed between 0700 h and 1000 h in the morning and 1600 h to 1900 h in the evening.All the bird species identified by sight or calls were recorded along with their number.Only confirmed identified bird species were included in the study.
The total count method was used to determine the richness of water birds.Species were recorded along with their number from morning hours till noon (0700-1200 h).Since it was not possible to cover the entire 'Saraiyaman Lake' from a single point, birds were counted by selecting more than one point.The survey was not conducted during adverse climatic conditions like rain and cloudy days.Bird species recorded were classified into various feeding guilds and migratory status based on the diet descriptions available (Ali & Ripley 1987;Grimmett et al. 2011).Sorenson's similarity index was used to calculate the similarity between bird species in different study sites using the following formula:

RESULTS AND DISCUSSION
A checklist of 424 species; 298 terrestrial, 82 water birds, and 44 water-associated ones representing 20 orders and 78 families was compiled from four PAs of the Terai-Arc landscape (Table 1).The diversity of birds might be underestimated because some may have been missed due to their cryptic nature and observer inattention.The total bird species compiled from PAs of Terai-Arc Landscape represents around 30% of the Indian Subcontinent (Praveen et al. 2019) and 47% of the Indian Himalaya (Mandal et al. 2018) indicating that Terai-Arc landscape as among the most avifaunal diverse regions of India.The Terai-Arc landscape is located at the confluence of the Himalaya and Gangetic plains (Rodger & Panwar 1988) and hence supports species of both biogeographic zones.
The richness of species was observed maximum in KWS (n=358), followed by VTR (n = 306), PTR (n = 236), and UWS (n = 128, Table 2).The high richness of birds in KWS may be attributed to the structural complexity and diverse habitat that offer foraging and nesting opportunities to birds (Tews et al. 2004;Ahmed et al. 2019).Moreover, the Terai-Arc landscape is a mosaic of diverse habitat types; sal-forest, sal-mixed forest, dry riverine forest, moist riverine forest, grassland, scrubland, open lands, and wetlands and rivers (Chanchani et al. 2014).Benton et al. (2003) highlighted a heterogeneous landscape is likely to support more species owing to the (a) specialization of various resources and, (b) reduced competition between species (Fahrig et al. 2011) and landscape complementation (Dunning et al. 1992).
In VTR, an earlier study conducted by Choudhary (2016) has reported 246 species.Of these, 205 were found common with the present study (n = 306).There are 40 bird species such as Amur Falcon Falco amurensis, Vernal Hanging-Parrot Loriculus vernalis, Red-breasted Parakeet Psittacula alexandri, and Plumbeous Redstart Rhyacornis fuliginosa reported by Choudhary (2016) that we didn't report.We recorded 101 different species which were not observed in the earlier study by Choudhary (2016).
In PTR and UWS, no scientific studies have been carried out so far.However, records in the management plan of UWS report 91 species, of which, 89 were common with the present study (n = 128).

Vultures
Seven species of vultures: White-rumped Vulture (WRV), Indian Vulture (IV), Slender-billed Vulture (SBV), Red-headed Vulture (RHV), Egyptian Vulture Neophron percnopterus (EV), Himalayan Vulture Gyps himalayensis (HV) and Griffon Vulture Gyps fulvus (GV) were recorded from the PAs of Terai-Arc Landscape.In KWS, a flock of 155 individuals consisting of WRV (n = 152) and IV (n = 3) was sighted feeding on a cattle carcass near Bichia village in 2001.Besides, 32 active nests of WRV were found along the Girwa River.During March 2016, a mixed flock of HV, WRV, and SBV was sighted feeding on carcasses between Dhakerwa town and Bichia market near Katerniaghat WS.In VTR, a mixed flock of WRV and IV were sighted feeding on carcasses in the Harnatand range (36 individuals), perching on a Bombax ceiba tree in Valmiki Nagar Range (RHV: 1, HV: 2), and flying over Ganauli range (EV: 1).

Greater Spotted Eagle Clanga clanga
Vulnerable.A single bird was observed twice in the winter on the banks of Gandak River in Valmikinagar range of VTR in the last week of December 2016.

Bengal Florican Houbaropsis bengalensis
Critically Endangered.In PTR, a male Bengal Florican was sighted in Chaugebi grassland, Mahof range during April 2014.This species is considered as one of the most endangered bustards of the world.In Uttar Pradesh, the recorded estimated population of this species was 22 individuals (Sivakumar et al. 2014).Javed & Rahmani (1998) expected the possible occurrence of this species in KWS, however, no sighting of this species occurred during the survey.The patches of short grasses and mosaic of agriculture field throughout the terai is considered potential habitats for Bengal Florican.

Swamp Francolin Ortygornis gularis
Vulnerable and endemic to the Indian subcontinent, a small population is distributed along the foothills of the Himalayas in tall and swampy grasslands of Terai as well as the floodplains in northern India and Nepal.During the 2001 survey, the bird was sighted frequently on Bund road in Katerniaghat range.A maximum of 12 individuals were sighted in marshy habitats around 4-5 km before Kailaspuri gate in KWS.However, no individual was sighted during 2015.Two individuals of Swamp Francolin were seen on 23 Dec 2016 in the swamp habitat of Madanpur range in VTR.

Indian Skimmer Rynchops albicollis
Endangered.Seven individuals of Indian Skimmer were observed flying over the Girwa River on 24 April 2015 in Katerniaghat (Image 2).Earlier studies in the KWS have not highlighted the occurrence of this species (Kalam 2005;Sethy & Chauhan 2011;Rahmani et al. 2016).No sightings were reported from PTR, Dudhwa NP, and VTR.

White-eared Night Heron Gorsachius magnificus
Endangered.An immature female of White-eared Night Heron was photo-captured on 24 November 2016 in a camera trap deployed near a slow-flowing perennial rivulet surrounded by moist deciduous forest type in Raghia range of VTR (Image 3).The species was recorded for the first time in Indian subcontinent (Shafi et al. 2018).The species is very rare with only 250-999 mature individuals distributed over southern and eastern China and northeastern Vietnam (BirdLife International 2017).J TT (Grimmett et al. 2011).

Woolly-necked Stork
An analysis of avian species composition between the PAs indicated KWS had a high similarity index value with PTR (S = 0.77) and VTR (S = 0.74, Table 3).PTR shared a high proportion of similar species with VTR (S = 0.69, Table 3).Avian community composition of UWS differ from rest of PAs; PTR (S = 0.58), KWS (S = 0.50), and VTR (S = 0.50).This might be related to the prevalence of similar habitat, i.e., woodland in Valmiki, Pilibhit and Katerniaghat (Chanchani et al. 2014).Since majority of area of UWS is under wetland, hence different bird community structure could be expected.
Based on their food preferences, a majority of bird species (190 species, 44.8%) belonged to the insectivorous guild, followed by carnivores (88 species, 20.7%) and omnivores (70 species, 16.5%) (Figure 4).Nectivorous guild was the least represented guild in the region (10 species, 2.35%).The dominancy of insectivores has been observed in various regions of India (Sultana & Khan 2000;Sultana et al. 2007;Aggarwal et al. 2008;Acharya et al. 2010;Joshi & Bhatt 2011;Ahmed et al. 2015).High tree density along with moist conditions favour richness and abundance of insects (Erwin 1982;Chettri et al. 2005).Since the study was carried out in PAs with high tree density (FSI 2019), hence dominancy of insectivorous species in Terai-Arc landscape could be expected.
Terai-Arc landscape is a biologically diverse ecoregion and has been listed among the conservation landscapes of global importance for its unique Terai-Duar Savanna and Grassland habitats, which support more than 600 species of birds (Chanchani et al. 2014).Many Critically Endangered species were observed here during the study, showing the potential of the landscape as a good habitat for avifauna.The study will serve as  J TT baseline data for better management and conservation of the existing species.Further long-term studies in the landscape in different seasons are required to prepare a holistic checklist of birds found here as our study had limitations of being not continuous in all the mentioned PAs.Since the forest area in the landscape is surrounded by the rapidly increasing human population, which traditionally depends upon forest resources such as fuelwood, fodder, non-timber forest products and grazing, posing a serious threat to the habitats of the PAs (Wikramanayake et al. 2010).The presence of an all-weather road and railway track inside the KWS and VTR is leading to a high level of disturbance (Maurya & Borah 2013;Chanchani et al. 2014).Water bodies in KWS and UWLS are very important for water birds including waders, many winter visitors and local migrant species recorded here.Illegal fishing is one of the threats to water birds observed here (Chanchani et al. 2014).
The infestation of grassland by Lantana spp.due to over-grazing and other human-induced disturbances, including fire as management practice, are among the major threats to the grassland ecosystems (Javed & Rahmani 1998).The present study reports nearly 19% species (n = 80) are dependent on grassland and grassland-associated habitats, therefore conservation of grassland with adequate scientific knowledge with proper monitoring plan is needed.

Figure 1 .
Figure 1.Map of study areas in Terai Arc landscape, India.
Habitat type: GL-Grassland | AGR-Agricultural grassland | WGL-Wooded grassland | ML-Marshland | SF-Sal forest | MF-Mixed forest | RF-Riverine forest | WL-Wetland | RB-Riverbank | DG-Degraded.Numeral represents year of sightings in study areas.IUCN Red List status: CR-Critically Endangered | EN-Endangered | NT-Near Threatened | LC-Least Concern | VU-Vulnerable.Status in PAs: R-Resident | WV-Winter visitor | SV-Summer visitor | LM-Local migrant | PM-Passage migrant | UC-Uncertain | VA-Vagrant.J TT 2002.An individual was also sighted in February 2016 between Naughat and the watch tower in Katerniaghat range of KWS.And another individual near Koleshwar mandir on the bank of Gandak river in VTR during March 2017.
Ciconia episcopus Vulnerable.Except for Udaipur WS, Woolly-necked Stork was commonly sighted in groups of one to four individuals in and around the PAs (Image 4).In PTR, a single individual was sighted on 16 February 2014 in the Mala range and on Madhotanda road on 29 March 2016.In Katerniaghat, two individuals were sighted on the bank of Girwa river near watch tower in Katerniaghat range during March 2008 and four individuals in bhainsalot phanta (grassland) in Nishangada range during April 2008.In VTR, an individual of Woolly-necked Stork was sighted in Bhasahwa and Madrahwa ghat in the Madanpur range on 17 and 22 January 2017.Lesser Adjutant Leptoptilos javanicus Vulnerable.A group of 24 individuals was sighted in a crop field around 2 km from Madanpur forest rest house towards Bagaha road in VTR in February 2017.In KWS, three individuals of Lesser Adjutant were sighted on Banda road near Mantri Mod on 28 March 2006.Two individuals were recorded in Sujauli range while Image 1. Steppe Eagle.© Shariq Safi

Figure 2 .
Figure 2. Order-wise richness of avian species observed in protected areas of Terai-Arc landscape, India.

24707-24729 Avifauna of four protected areas of Terai-Arc Landscape Safi et al. 24714 J TT Family Species name Habitat Feeding guild IUCN Red List status KWS PTR VTR UWS Status in PAs
Journal of ThreatenedTaxa | www.threatenedtaxa.org| 26 February 2024 | 16(2):

24707-24729 Avifauna of four protected areas of Terai-Arc Landscape Safi et al. 24718 J TT Family Species name Habitat Feeding guild IUCN Red List status KWS PTR VTR UWS Status in PAs
Journal of ThreatenedTaxa | www.threatenedtaxa.org| 26 February 2024 | 16(2):

24707-24729 Avifauna of four protected areas of Terai-Arc Landscape Safi et al. 24720 J TT Family Species name Habitat Feeding guild IUCN Red List status KWS PTR VTR UWS Status in PAs
2017 R Journal of Threatened Taxa | www.threatenedtaxa.org| 26 February 2024 | 16(2):