The earth has become urbanized at an accelerating rate, with more than half of its population now living in cities. Human land use and resource consumption have profound impacts on the natural patterns and processes at the city, region, and global scales. But while humans are clearly the dominant drivers of urban ecosystems, animals living in cities can also play important roles. For example, movement of chemicals from human food sources into otherwise isolated urban forests by animals can produce unique chemical hot spots with multiple potential consequences. Even so, very few studies have linked the movement of chemicals with the behavior and dynamics of urban wildlife populations. This project will explore the links between the nesting behavior of American crows and the movement of nitrogen to create hotspots in the many small to medium sized cities in central New York. Under-represented minority students from local areas will be recruited for the project, which will also involve citizen scientists and lead to increased public awareness of human-nature connections. The project will also provide a base of science to local city managers and county soil and water conservation managers.
The central hypothesis of this project is that when urbanized American crow populations forage on human-subsidized food sources and roost in high densities in urban forest patches, they create high ? and sometimes episodic - nitrogen availability. That changes the pattern of nitrogen cycling in the forest fragments, affects critical ecosystem processes of denitrification and nitrogen leaching, and causes localized water and air pollution. This study poses two main questions. First, what is the distribution of crow roosts and its association with cities and towns? Second, what are the biogeochemical consequences of concentrated N input from crow roosts? The study will investigate a novel linkage between crow behavior, including foraging, roosting and defecating, and the formation of biogeochemical hot spots. It will compare and contrast nitrogen transformations and transfers between the hot spots and urban sites without concentrated bird activities. It will examine the patterns and mechanisms regulating different pathways of N loss (leaching vs. denitrification) and various potential end forms of nitrogen gas and dissolved losses in urban hot spots receiving pulsed, concentrated N input. Finally, it will advance urban ecological research by integrating population and ecosystem level studies beyond the usual foci of humans and trees. The project will examine fundamental aspects of how animal species affect ecosystem function in the novel context of a spatially heterogeneous urban landscape (driven by human land use decisions) and supplemental energy and material (driven by human food consumption).
