Essay About Semi-Evergreen Forest Habitat And V. V. Robin

The Birds
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Five species of shortwings (genus Brachypteryx, subfamily Turdinae) exist; four of which are found in the Himalayas. The fifth, the endemic White-bellied Shortwing Brachypteryx major, is the only shortwing found in the Western Ghats, South India and has two subspecies: B. m. major and B. m. albiventris. It has been described as ‘‘a shy and retiring species, affecting deep shades, found singly or in pairs in the undergrowth, rarely above three metres’’ (Ali and Ripley 1987). It is known only poorly, with just 78 records from 1881 to 2000, inclusive of both sightings and collections (20 from Kerala and 58 from Tamilnadu). There are also 113 ringing records for four years between 1970 and 1991 (Appendix 1). Although it was reported to be fairly common by Ali and Ripley (1987), there are very few recent records and the species has been listed as Vulnerable (+2a,b,c,d,e; BirdLife International 2001).

Of the various factors that may cause population decline, hunting and direct toxicological effects can be ruled out, as White-bellied Shortwing is neither a

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game bird nor one that is found in the proximity of industrialized areas. The most likely cause of the population decline of this species is habitat loss, frag- mentation or degradation. BirdLife International (2001) states that the ‘‘species has a small, severely fragmented, declining range owing to destruction and frag- mentation of its evergreen and semi-evergreen forest habitat’’. Before undertak- ing a detailed, long-term study to understand the biology and decline of the species, it was thought imperative to know its habitat preferences and abundance in different areas across the Western Ghats. This study therefore aimed to look at: (i) habitat preferences with reference to (a) altitude and (b) forest type; and (ii) abundance in different areas, with particular attention to areas of high local abundance, if any. The study covered the parts of the Western Ghats in Kerala and Tamilnadu as the first phase of a survey to cover the entire Western Ghats.

Methods
The study period consisted of four months of fieldwork, from 25 January to 20 May 2001. Areas with recent, frequent sightings of White-bellied Shortwing were identified from available literature and personal communications with various field biologists (Appendix 1). Two such areas, namely Rajamalai in Munnar, Kerala and Cairnhill Reserve forest in Ooty, Tamilnadu were visited to familiar- ize the authors with both subspecies of White-bellied Shortwing. For this pur- pose, observations were conducted from 05h00 to 18h00 every day (logistics permitting) for one week at each site. Once a bird was located and identified, it was followed for as long as possible. The calls were recorded (Sony WM- D6C recorder with Sony microphone) and motion as well as still pictures were taken (Pentax SF7 camera with Zigma 300 mm zoom lens, Sharp video camera). Peak activity time was noted as the time when most shortwings were singing. The survey commenced only after obtaining confidence that the bird could be identi- fied by sight or call without confusion.

For the full surveys, several forest areas in Kerala and Tamilnadu were chosen, representing different habitats at different elevational gradients (Appendix 2). Trails inside forests were walked in the morning (07h00 to 12h00) and afternoon (14h00 to 18h00) while looking and listening for shortwings. The habitats sampled were categorized into tropical wet evergreen forest (evergreen forest), montane temperate forest (shola forest), tropical moist-deciduous forest, or plantations, based on Champion and Seth (1968). The montane temperate forests have been better described as montane evergreen forests (Mehr-Homji 1984, Shanker and Sukumar 1999) and