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Contents : FORKTAIL 16 (2000): 1-3 Roost counts of harriers Circus spanning seven winters in Andhra Pradesh India T. GANESH and P. KANNIAH A roost of four species of wintering harriers (Eurasian Marsh Circus aeruginosus Montagu C. pygargus Pallid C. macrourus and Hen Harrier C. cyaneus) was monitored for a period of seven years from 1986 to 1994 at a grassland site near Secunderabad India. Eurasian Marsh Harriers accounted for more than 30% of harriers at the roost followed by ringtails and juveniles of Montagu s Pallid and Hen Harriers. A peak roost of over 200 harriers occurred in 1988 1989. Counts were not highly variable between years but a perceptible fall in numbers was noticed over the years. Peak numbers occurred in October and there was no significant increase later in the winter. Local factors such as grass cutting probably affected roost numbers. A survey of a network of sites is proposed to better ascertain regional trends in numbers. INTRODUCTION Long-term monitoring of bird numbers in India has been carried out for waterfowl species (Perennou et al. 1994) and for grassland birds such as the Great Indian Bustard (Rahmani and Manakadan 1988) and floricans (Narayan et al. 1989). Other migrants such as raptors have not been regularly monitored. Being at the pinnacle of the food chain raptors deserve more attention on their wintering grounds (Newton 1979). The migrant raptors which winter throughout the Indian subcontinent include several species of harriers Circus (Ali and Ripley 1983) which congregate in large numbers at grasslands for roosting (Rahmani and Manakadan 1986 Clarke 1996a Kanniah and Ganesh in press). Study Area Counts of harriers were made at a grassland roost site located in a mosaic of agricultural semi-urban and scrub forest habitat near Alwal 10 km north of Secunderabad Andhra Pradesh India (17 25'N 78 15'E). The area is about 550 m asl and receives about 800 mm of rainfall annually. The grassland near Alwal is approximately 1 km2 in size with complete grass cover and is maintained as a military dairy farm with periodic fodder harvesting. Though developed along the fringes this area remains relatively isolated and free from any major interference. Counts were made each winter 1986/1987 to 1993/1994 except for 1991/1992. METHODS Roost counts Counts were made in the evenings. Two strategic points at opposite ends of the grassland were chosen from which harriers were counted by each author independently. It was possible to keep track of incoming individuals because the grassland was on a slope with a shallow depression in the middle and could be watched from either end. Harriers approached largely from one direction. Observations began about 2 hours before actual settling of the birds and each incoming individual was recorded. Birds already in the area before counting started and those in an adjacent pre-roost site were taken account of. Complete counts of birds milling before roosting were also made and were compared with the arrival counts. Both the counts tallied well and so counts during milling were not analysed. Counts were generally made at intervals of ten days. Weekly observations were made early in the season because the variability in numbers was high over a short period then and the chances of missing the maxima at intervals of ten days was high. Later in the season variability was very low. Peak numbers of birds sighted per month were used as data for analysis. The sex of individuals was noted where possible. However birds often could not be sexed due to distance or poor light conditions. Ringtails and juveniles of Montagu s Pallid and Hen Harriers were pooled into a single category as they look similar in the field. These are referred to as ringtails and juveniles in this paper. Grass cutting was evaluated by the time taken to harvest the grass. RESULTS Species composition Five species of harriers: Eurasian Marsh C ircus aeruginosus M ontagu s Harrier C. pygargus Pallid Harrier C. macrourus Hen Harrier C. cyaneus and Pied Harrier C. melanoleucos were recorded. The last two occurred irregularly and the Pied Harrier in particular was rare. Confirmed roosting of Hen Harriers was recorded only from 1989-1990 onwards. The other three harrier species occurred in all seven winters of observations. By far the most frequently recorded species was the Eurasian Marsh Harrier which contributed more than 30% of the summed counts (7 822 birds) followed by ringtails and juveniles of Montagu s Pallid and Hen Harriers (24%). Fluctuations in numbers Harriers were present from early September to mid April. The mean monthly peak numbers of harriers counted during each winter are shown in Table 1. Maxima 2 T. GANESH & P. KANNIAH Forktail 16 (2000) Table 1. Peak counts of each category of harrier Circus counted at their roost site near Alwal Andhra Pradesh India Winters Total Montagu s (males females (males) and juveniles) 19

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