Professor University of Michigan Ann Arbor, Michigan, United States
As urbanization continues at a rapid pace around the globe, there is a growing concern about the impacts of habitat fragmentation on wildlife. Previous research has shown birds respond to urbanization in a variety of ways, with species often labeled as urban-adapters or urban-avoiders. Understanding why some bird species respond positively or negatively to urbanization is vital to proper management and planning conservation of native biodiversity. In this meta-analysis, we studied trends in the abundance of birds across the urbanization gradient and at sites with various annual averages of fine particulate matter (PM2.5) pollution. Although there is a swath of research on how PM2.5 pollution negatively impacts the health of humans, there is a lack of studies assessing the impacts on wildlife. We conducted a literature review and investigated the changes in abundance of birds across the urbanization gradient at sites around the world. We categorized sites from least to most urbanized, as biological preserves, agriculture or open-space recreational areas, golf courses or residential parks, residential neighborhoods, office parks or apartments, and business districts. We found the variation in abundance across the urbanization gradient correlated with life history traits of each species and the level of PM2.5 at each location. We hypothesize that the patterns of change in abundance across the urbanization gradient are related to the PM2.5 levels at the site and the species' life history traits. We have found that the urban response of a species is significantly different based on several life history traits including their nest type, preferred habitat, and diet. Parasite nesting birds have a more positive urban response while other nesting types all have an overall negative response to urbanization. Bird species that prefer Human Modified habitats also have a positive urban response. Birds with a granivore diet had a positive urban response, scavenger birds had the most negative urban response, and birds with an omnivore diet had an overall neutral response to urbanization. In conclusion, this study suggests that we need to consider the species of native birds’ life history traits when planning conservation projects and we need more studies on pollution impacts on wildlife.
