Population density, survival, and rabies in raccoons in an urban national park

Abstract

Density and survival of a raccoon (Procyon lotor) population in Rock Creek Park, an urban national park inWashington, D.C., were estimated using mark–recapture and radio-tracking over an 8-year period following the appearance ofthe mid-Atlantic States (Mid-Atlantic) rabies epizootic. Raccoon density ranged from 333.3 to 66.7/km2 , with an overall parkestimate of 125/km2 . This density places the Rock Creek population within the range of other urban and suburban populationsand is many times greater than raccoon densities reported from other habitats. Density was particularly high in one thin spur ofparkland with the smallest ratio of area to urban edge. Raccoon survival rates were high except among juveniles during therabies epizootic. Data on rabies prevalence from Washington, D.C., indicate a cycle with peaks in 1983 during the initialepizootic and again in 1987 and 1991, a pattern similar to that seen in other carnivores and in rabies models. We found evidenceof decreased raccoon density during and after the 1987 rabies resurgence relative to the years following the original epizootic,when rabies prevalence was low. While hunting and trapping represent a major mortality factor for many rural raccoonpopulations, urban and suburban populations and protected populations may frequently be subject to epizootics of diseasessuch as canine distemper and rabies, even years after initial contact with a disease.

Raccoon use of the urban matrix in the Baltimore Metropolitan Area, Maryland

“…Our results provide multiple lines of evidence that raccoons operate as a synanthropic species in the suburban Baltimore area, even in the urban matrix with reduced woodland habitat. Our density estimates are within the range reported for raccoons in urban areas, which have ranged between 38-125 raccoons/km 2 (Hoffman and Gottschang 1977; Rosatte et al Riley et al 1998;Prange et al 2003). However, these previous estimates are primarily for raccoons associated with urban parks or open spaces.…”

“…Raccoons have been observed readily utilizing anthropogenic resources, such as refuse for food and human structures for dens (Gehrt 2003;Hadidian et al 2010), and population densities reported for urban areas have consistently been high when compared to rural areas (Rosatte et al 1991;Riley et al 1998;Prange et al 2003). Likewise, home ranges are relatively small in size for raccoons in urban areas which, when combined with high population densities, produces an abundance that tends to exceed other mesocarnivores .…”

“…Indeed, urban raccoon populations appear to occur at their highest densities in woodland fragments embedded within the urban matrix (Rosatte et al 1991;Riley et al 1998;Prange et al 2003). It is important to note that most of the information on the urban ecology of raccoons, especially via radiotelemetry, has come from research focused on these natural fragments, such as urban parks or preserves.…”

THE IMPACT OF LAND USE, SEASON, AGE, AND SEX ON THE PREVALENCE AND INTENSITY OFBAYLISASCARIS PROCYONISINFECTIONS IN RACCOONS (PROCYON LOTOR) FROM ONTARIO, CANADA

“…An increase in contact rates between raccoons has been linked to higher prevalence of B. procyonis (Gompper and Wright 2005). Raccoons in urban areas often live at very high densities (Riley et al 1998), and male urban raccoons may be less solitary than their rural counterparts (Prange et al 2003), so the higher prevalence we detected in male raccoons may be a result of increased contact rates among urban male raccoons. There was no difference in the prevalence of B. procyonis in female raccoons from suburban/urban versus rural areas in either time period.…”

“…Raccoons can live at high densities in urban areas (Riley et al 1998), with population estimates of 37-94 raccoons/ km 2 in an urban area in southern Ontario, Canada (Broadfoot et al 2001). High raccoon density, combined with their close association with humans, has led to concerns about increased risk of pathogen transmission to humans in urban areas.…”