Making the most of what remains: Examining the quality of urban grasslands for birds in Illinois

Abstract

Grassland bird populations have experienced steep declines across North America, with especially precipitous declines in the Midwest. The primary cause of these declines is thought to be loss and fragmentation of grassland habitat. Illinois alone has lost >99% of its native prairie, and has steadily lost agricultural grasslands over the past 50 years. Despite this statewide decline in grassland availability, there are >12,000 ha of grassland in the Chicago region that may provide valuable habitat for imperiled grassland bird species. However, little is known about the value of grasslands located in an urban matrix. To investigate whether grassland birds are using these grasslands and whether they support viable populations, I examined grassland bird habitat use, reproductive success, and nest predator identities along an urban-to-rural gradient in the greater Chicago metropolitan region. Of the seven obligate grassland species I studied, only Sedge Wrens (Cistothorus platensis) displayed a strongly negative association to the amount of development in the landscape. I found that nest predation rates decreased in more developed landscapes, as did the probability of brood parasitism. I also found that coyotes (Canis latrans) and white-tailed deer (Odocoileus virginianus) were the dominant nest predators in this study system. This research contributes to an ongoing effort to define what factors are important for designing grassland bird conservation areas in urban landscapes.