Ecology and ethno-ornithology of Black Kites Milvus migrans in Delhi, India

Rapid worldwide urbanization is generating a steep growth in studies on urban ecology, but tropical cities have had extremely scarce attention. To fill this gap of knowledge, in this thesis, I studied a dense population of an avian predator and facultative scavenger, the Black Kite Milvus migrans, breeding within Delhi, a megacity with16-million-inhabitants. I studied the ways in which this species managed to adapt, respond and exploit such an extreme urban environment by running analyses at the individual as well as population-level, through sampling at 28 independent plots, stratified and (randomly) scattered, to cover all the urban configurations present in Delhi. In particular, I focused on the dependence of this population on anthropogenic subsidies, afforded as human waste (in the streets or at refuse tips) and as intentional “ritual offerings” of meat scraps for religious purposes, especially by people of Islamic faith that are concentrated in “Muslim settlements”. I found that the kite breeding population was stable over the past five decades, with a diet strongly dominated by human subsidies, especially ritual offerings, and with an extremely high density that makes it the largest raptor concentration of the world. Kites were not randomly distributed in the city but over-selected areas with high human density, poor waste management and a road configuration that facilitated ready access to resources provided by humans, in particular to Muslim colonies that provided ritual subsidies. Rather than a nuisance to avoid, as previously portrayed, humans were thus a keenly-targeted foraging resource. These individual-level preferences translated into population-level effects, with kite density tightly tied to Muslim subsidies. This relationship was further modulated by nest-site availability, mainly in the form of tree availability, which paved the way to potential population manipulation through tree management. Ecological responses were accompanied and mediated by behavioural adjustments to the urban gradient, which provided adaptive benefits and generated potential conflicts with humans. In particular, offspring defence was finely-tuned on human subsidies, probably as a result of the associated parental investments and familiarity with humans. In its most extreme form, nest defence led to attacks on humans, sometimes with serious physical harm. I show that such aggression was tied to frequent exposure to humans by kites while accessing their ritual subsidies and by constant close proximity to them while breeding, as caused by local architecture (balconies in the immediate proximity of nests). Despite the conflict, I also report the extremely benevolent attitudes of local people to the attacking kites, typical of southern-Asian cultural beliefs, but extremely unusual for western urban standards. Finally, I show how the stunning predator densities observed in Delhi are generated by the local breeding subspecies, but also by thousands of Black-eared Kites of the migratory M. m. lineatus subspecies that settle in Delhi during their wintering, non-breeding period. Through GPS-tagging, I found that they migrate to Delhi from their breeding quarters of Russia, Kazakhstan, China and Mongolia through a 3300-4700 km migration in which they regularly cross the Himalaya range at elevations of up to 5000-6000 m a.s.l., an aspect hitherto unknown. I discuss all my findings in terms of their contribution to broadening our views of urban ecology so that it is more inclusive of patterns and processes that better characterize the tropical cities of non-western nations. In particular, all my results stress the overriding importance of incorporating human socio-cultural factors in urban ecological studies