SHORT COMMUNICATION 246 TAPROBANICA VOL. 07: NO. 04 Microhabitat use and activity budget of four Himalayan river-birds, India A wide variety of river-birds are found in the Eastern Himalayan region of Northeast India, but the literature on microhabitat use and resource use patterns of these river-birds is very sparse. The fundamental processes that determine niche structures and influence niche segregation in coexisting species is a basic concern of community ecology (Rosenzweig, 1987; Pianka, 1988). For example, when territories of different species overlap, those species utilize different local resources or the same resources differently due to either niche complementarity or resource partitioning (Schoener 1974). Understanding the role of microhabitat has been an unending quest of avian autecology and community ecology (Hilden, 1965; Cody, 1968; Wiens, 1969, James, 1971; Karr, 1971; Anderson & Shugart, 1974; Wiens, 1974; Willson, 1974; Cody, 1981, 1985). Such studies, particularly when understood in terms of resource partitioning (Schoener, 1974), have been successful largely because of the fundamental importance of microhabitat to bird ecology. In the present study, we looked at the microhabitat preferences of four species of birds namely plumbeous water-redstart (Rhyacornis fuliginosa), white-capped water- redstart (Chaimarrornis leucocephalus), brown dipper (Cinclus pallasii) and slaty-backed forktail (Enicurus schistaceus) in Kamlang Wildlife Sanctuary (KWS). The KWS is located in the South-eastern part of Lohit District of Arunachal Pradesh (27°40’– 28°00’N, 96°26’–96°55’E) covering an area of 783 km 2 with elevation ranging from 500 to 4500 m asl (Nageshwara & Chowlu, 2006). It experiences moderate temperatures and high humidity in lower areas, and intense cold in the upper reaches. Studies were done during the months of February and March 2012 in the second order channels of the river Kamlang located between 400–500 m altitude as these channels lie adjacent to the trek paths of the sanctuary. The width of the river streams ranged between 25–30 m. The activities of the four bird species were recorded based on their commonality of existence. We divided the river streams into two parts namely the central and the margin portions. The central portion included the boulders and fast moving waters and the margins included the stream bank, vegetation and boulders in the edges of the stream. The focal birds were observed for about 20.3 hours (plumbeous water-redstart: 6.2 hours, white-capped water-redstart: 5.4 hours, brown dipper: 4.6 hours, and slaty-backed forktail: 4.1 hours) in February 2012. Activity budgets of the birds were recorded whenever they were sighted either individually or along with other species. Observations were made by using binoculars (Olympus 8-16 × 40, Zoom DPS-I, Field 5.0°– 3.4°). Much care was taken to avoid eye to eye contact between the bird and the observer as the birds flew off whenever they sighted an observer. A stopwatch was used to calculate the time at every individual instance to the nearest one second. Behaviours were categorised as roosting, foraging, aggression/escape and others (Buckton & Ormerod, 2008). Aggression and escape are included under the same category because when a bird showed aggression the other tried escaping from the aggression. This behaviour included the time spent in chasing through flight or by pecking others. Foraging behaviour included all time spent by the birds in catching insects and time spent in walking in order to collect food. Roosting included the time spent in stationary postures. Other behaviours included preening etc. The plumbeous water redstart spent most of its time in the central portion of the habitat (mean: 79.0 ±1.4; n = 6). The white capped water redstart (mean: 76.5 ±3.2; n = 8), and slaty- backed forktail (mean: 65.8 ±1.4; n = 10) spent most of their time in the edges of the stream. Whereas, the brown dipper spent almost equal TAPROBANICA, ISSN 1800–427X. August, 2015. Vol. 07, No. 04: pp. 246–249. © Research Center for Climate Change, University of Indonesia, Depok, Indonesia www.taprobanica.org