Offal dumping sites influence the relative abundance and roosting site selection of Black Kites (Milvus migrans govinda) in urban landscape: a study from Kolkata metropolis, India

Abstract

Although Black Kites (Milvus migrans govinda) serve as major scavenging raptor in most of the urban areas, scientific studies on this important ecosystem service provider are almost non-existent in Indian context. The present study was carried out in a metropolis in eastern India to find out the factors influencing relative abundance and roosting site selection of Black Kites. Separate generalized linear models (GLMs) were performed considering encounter rate and roosting Black Kite abundance as response variables. The study conclusively indicated that encounter rates of Black Kites were significantly influenced by the presence of garbage dumps in its vicinity. Numbers of Black Kites were also higher in the roosting sites situated closer to garbage dumps and open spaces. In addition, expected counts of Black Kites significantly increased in roosting sites situated away from buildings and water bodies. However, built-up area and tree cover around the roosting sites had no influence on the abundance of Black Kites therein. With rapid urbanization and changing offal disposal patterns, our findings would be useful to ensure continued availability of food and roosting sites of Black Kites in urban areas.

Population status and feeding behavior of black kite (Milvus migrans) in Dhaka city, Bangladesh

“…Whereas on the dumping sites they feed on human food refuse, garbage and a byproduct of dressing (chicken refuse, cow refuse and fish refuse). Our findings are bit different than the previous reports where rodents, squirrels, fishes, insects, amphibians, reptiles and birds were mentioned as the main prey (Ferguson-Lees & Christie, 2001;Malhotra, 2007;Mazumdar et al, 2018). Others reported kites as opportunist hunters and have been known to take birds, bats and rodents (Narayanan, 1989).…”

“…Similar observation to a study carried out in India by Naoroji (2007). The black kites are generally seen foraging nearer to garbage dumps (Blanco, 1994;Mazumdar et al, 2018) or agricultural field where they could easily get copious of food in all seasons. A total of 18 feeding, 7 roosting and 7 breeding sites were recorded in study area (Table 1).…”

“…Road transects seem to be a reliable method to estimate the numbers of kites (Viñuela, 1997). For population estimation, road transect and morning roost-count methods was used (Fuller & Mosher, 1987;Ethier, 1993;Mazumdar, 2013;Mazumdar et al, 2017Mazumdar et al, , 2018 and to study various feeding and foraging behavior focal sampling method was used (Altman, 1974;Sharma & Soni 2017).…”

“…Accurate estimates of their population can be made by conducting surveys in these sites during certain months of the year and times of the day (Taylor, 1983). In addition, improved monitoring techniques consist of counting birds at their breeding or roosting sites early in the morning or late in the evening before or after their daily foraging trips (Robertson & Boshoff, 1986;Meyer, 1998;Mazumdar et al, 2017Mazumdar et al, , 2018. The black kites often gather in large communal roosts and breeding colonies.…”

Influence of habitat features of urban streetscapes on richness and abundance of avian species

“…Bushes are important mainly for forest-dwelling birds and urban avoiders to thrive in the human dominated habitats (Brandt et al 2013, Gopal et al 2018) and increasing number of buildings have been reported to decrease species richness (Evans et al 2009). Few species of urban exploiters and scavengers congregate around the markets and its adjacent garbage dumping sites (Mazumdar et al 2016(Mazumdar et al , 2018(Mazumdar et al , 2019 and forage on the refuse as these foods are plenty and predictable. However, we did not notice any significant influence of bushes, markets and buildings on the species richness and abundance of birds.…”