Variation in Demographic Patterns and Population Structure of Raccoons Across an Urban Landscape

摘要

Raccoons (Procyon lotor) are considered synanthropic, with high densities reported from urban landscapes. However, little information is available on population density and demography within the urban matrix. To better understand how urban land-use patterns influence raccoon density and demographic patterns, we sampled raccoons at multiple, replicated sites across an urban landscape. Density differed by land-use type (F-2,F-17 = 4.66, P = 0.027): urbanized sites, (x) over bar = 4.96 +/- 2.64 raccoons/km(2), range = 1.25-10.00 raccoons/km(2); urban open sites, (x) over bar = 14.84 +/- 6.35 raccoons/km(2), range = 3.00-29.25 raccoons/km(2); rural open sites, (x) over bar = 15.50 +/- 4.66 raccoons/km(2), range 13.00-20.25. Although we found no clear patterns in sex ratio, reproductive condition, or body condition, we observed differences in age structure among urban open, rural open, and urbanized sites. The most striking difference was the absence of older animals at urbanized sites and relatively low numbers of young individuals at urban open sites. Raccoons were the dominant mesocarnivore in open fragments, but less so in the urban matrix. Spatial variation in density across urban landscapes is likely influenced by site level differences in abundance of anthropogenic resources and differences in habitat quality. Furthermore, the association between changes in land-use and population age structure may have reflected different mortality sources across the landscape. Our results illustrate that wildlife species considered synanthropic may have complex relationships with urban landscapes. (C) 2012 The Wildlife Society.