In an urban environment, not all vultures are created equal
Not being picky about your food means you can live just about anywhere, and some vultures are good at adapting to landscape fragmentation caused by humans, but new research forthcoming in The Condor: Ornithological Applications shows that different vulture species use city environments in different ways.
The city of Manaus, Brazil, is home to two species—the gregarious Black Vulture (Coragyps atratus) and the shyer, more solitary Turkey Vulture (Cathartes aura)—and their presence has lead to a variety of problems, from the nuisance that results from vultures congregating around dumpsters to the serious hazard of bird-aircraft collisions. To learn more about how these two vultures navigate the urban landscape and to help manage potential human-vulture conflicts, Weber Novaes and Renato Cintra of Brazil's Instituto Nacional de Pesquisas da Amazônia made repeated visits to 80 sites around the city to record how many vultures were present, which type they were, and what might be attracting them.
Novaes and Cintra found that the more dominant Black Vultures were widely distributed around the city, attracted by trash containers and street markets where food waste is often left out in the open due to inadequate garbage collection, while Turkey Vultures were less abundant and found mostly on Manaus's outskirts and near forest fragments. "I became interested in studying vultures when I started my master's degree in 2005," explains Novaes. "There was a problem caused by the large concentration of vultures in the city of Ilhéus, Bahia, Brazil, which was a danger to aircraft, and this became the subject of my research." For his Ph.D., he continued his work on vultures in Manaus, a city that was carved out of the Amazon rainforest and is dotted with forest fragments and crisscrossed by streams.
Novaes and Cintra suggest that the vigilant removal of small animal carcasses from the airport grounds, as well as possibly modifying aircraft lighting and removing or blocking access to perches, could make the airport less attractive to the area's Turkey Vultures. From January 2011 to May 2013, there were 12 collisions between vultures and aircraft at Manaus's airport, most of which involved Turkey Vultures. Turkey Vultures often fly at lower elevations than Black Vultures and prefer smaller food items, and they are likely attracted to the forested areas and populations of small animals in the airport area.
"Populations of Black and Turkey vultures continue to expand, and these species are increasingly in conflict with human activities. Each species displays an opportunistic, adaptable lifestyle compatible with urban environments," according to USDA scientist Michael Avery, an expert on vulture management. "The findings of this study reflect differences between species in social and foraging behaviors, and they provide a foundation for developing species-specific management plans to reduce property damage and hazards to aircraft in Brazil and elsewhere in the range of the species."