Variation in demographic patterns and population structure of raccoons across an urban landscape

Abstract

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 2,17 ¼ 4.66, P ¼ 0.027): urbanized sites, x ¼ 4.96 AE 2.64 raccoons/km 2 , range ¼ 1.25-10.00 raccoons/km 2 ; urban open sites, x ¼ 14.84 AE 6.35 raccoons/km 2 , range ¼ 3.00-29.25 raccoons/ km 2 ; rural open sites, x ¼ 15.50 AE 4.66 raccoons/km 2 , range ¼ 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. ß 2012 The Wildlife Society.

Population Ecology of Free-Roaming Cats and Interference Competition by Coyotes in Urban Parks

“…For example, striped skunks ( Mephitis mephitis ) were 60% seropositive for T. gondii [22], raccoons ( Procyon lotor ) 38% [23], and coyotes range from 38 to 63% annually (Gehrt unpublished data). Our results for T.…”

Wildlife Population Dynamics in Urban Landscapes

“…For example, urban landscapes Graser et al 2012) typically support comparatively few insectivorous and migratory birds relative to nonurban areas (Beissinger and Osborne 1982;Rodewald and Bakermans 2006). Snakes, too, tend to decline in number with urbanization (Patten and Bolger 2003), in part due to vehicular-related mortality and persecution (Akani et al 2002).…”

Born to be wild? Response of an urban exploiter to human-modified environment and fluctuating weather conditions

“…We showed that distinct life stages and sexes respond contrastingly to environmental characteristics at different spatial scales, in opposite directions, and with variable effect sizes. Many studies focused exclusively on the general impact of human activity (i.e., urbanization) and its effect on body mass (Cypher and Frost 1999;Auman et al 2008;Graser et al 2012). We went further by trying to disentangle the effect of being near humans and being near food sources provided by humans.…”

“…For example, it has been shown for several species that individuals inhabiting urban areas or areas in close proximity to artificial food sources are heavier (Cypher and Frost 1999;Beckmann and Berger 2003;Wright et al 2012). Conversely, body mass in other successful urban species appeared unrelated or negatively affected by human activity (Hungerford et al 1999;Graser et al 2012). Furthermore, in some circumstances, effect of humandriven changes varies according to sex or life stage.…”

“…Such high densities are likely caused by the presence of abundant artificial resources that are by-products of human activity, such as discarded foods or unused buildings (for a review see Bateman and Fleming 2012). Identifying how novel ecological factors emerging from human activities affect wild animals is critical to improve management of human-adapted abundant species and species of conservation concern (Bateman and Fleming 2012; Graser et al 2012).…”