Naperville, IL, United States
Naperville, IL, United States

Time filter

Source Type

Newsome S.D.,University of New Mexico | Garbe H.M.,Max McGraw Wildlife Foundation | Wilson E.C.,Ohio State University | Gehrt S.D.,Max McGraw Wildlife Foundation | Gehrt S.D.,Ohio State University
Oecologia | Year: 2015

With increasing urbanization, some animals are adapting to human-dominated systems, offering unique opportunities to study individual adaptation to novel environments. One hypothesis for why some wildlife succeed in urban areas is that they are subsidized with anthropogenic food. Here, we combine individual-level movement patterns with diet composition based on stable isotope analysis to assess the degree to which a rapidly growing population of coyotes (Canis latrans) in Chicago consumes anthropogenic resources. We used telemetry to classify coyotes into three groups based on social class and home range composition: (1) residents with home ranges in urban nature preserves; (2) residents with home ranges that had a high proportion of urban land; and (3) transients that had relatively large home ranges and variable use of urban land. We found that natural and anthropogenic resources in this system can be reliably partitioned with carbon isotopes. Mixing models revealed that resident coyotes associated with most urban nature preserves consumed trace to minimal amounts of anthropogenic resources, while coyotes that live in the urban matrix consume moderate (30–50 %) to high (>50 %) proportions of anthropogenic resources. Lastly, we found evidence of prey switching between natural and anthropogenic resources and a high degree of inter-individual variation in diet among coyotes. In contrast to the expectation that urban adaptation may dampen ecological variation, our results suggest individuality in movement and diet exemplifies the successful establishment of coyotes in urban Chicago. Our study also suggests that direct anthropogenic food subsidization is not a prerequisite for successful adaptation to urban environments. © 2015, Springer-Verlag Berlin Heidelberg.


Hauver S.A.,Ohio State University | Hauver S.A.,Max McGraw Wildlife Foundation | Gehrt S.D.,Ohio State University | Gehrt S.D.,Max McGraw Wildlife Foundation | And 5 more authors.
Journal of Mammalogy | Year: 2010

Spatial dynamics and frequency of interaction between mating individuals are difficult to observe in the wild, and linking behavioral and genetic mating systems is particularly challenging for nocturnal or otherwise cryptic mammals. We monitored 29 (11 male and 18 female) adult raccoons in northeastern Illinois to gain a better understanding of how individuals interacted with one another during the mating season (DecemberMarch) of 2005. Adults were monitored with proximity-detecting radiocollars to determine the amount of spatial overlap and rate of contact among members of the local population, including those parent pairs that had mated successfully. We identified successful matings by conducting parentage analyses on 43 juveniles using 15 highly variable microsatellite loci. We were unable to identify parents for 25 of 43 juveniles, which greatly reduced our ability to assess the raccoon mating system. However, we present novel data on contact rates and den-sharing incidents between known parental pairs. We found that 3 of 4 parent pairs shared >35% of their daytime resting areas and >26% of their core resting areas. Contact rates of parent pairs varied, ranging from 0•1 to 0•9 contacts/day. Parent pairs were not observed to share dens during the mating season. However, among the remainder of the adult population, we found a sharp increase in instances of den sharing between unrelated adults that coincided with the peak of the mating season. Finally, male coalitions were not successful at sequestering breeding access to reproductive females; only 38•8% of juveniles were sired by males known to live in groups. © 2010 American Society of Mammalogists.


Hauver S.A.,Max McGraw Wildlife Foundation | Gehrt S.D.,Ohio State University | Prange S.,Max McGraw Wildlife Foundation
American Midland Naturalist | Year: 2010

The response of postparturient females to conspecifics at the natal den can provide insights into intraspecific dynamics, particularly the risk of infanticide. In solitary species, the risk of infanticide may be high and mothers are expected to secure dependent young in dens and tolerate little, if any visitation by males. We monitored 10 male raccoons (Procyon lotor) and 11 females from pregnancy through lactation that were equipped with proximity detecting collars during the neonate rearing period (Apr.Jul.). Natal den trees were identified and proximity detectors were also attached to these trees to document the mother's movements and visitation by conspecifics. A total of 21 den trees (18 dens/mother) were used, yielding 337 den-nights of data. Besides those of the mother, 284 visits (02.9 visits/night) were recorded and dens were visited by three to 10 individuals. Time spent away from the den by the mother increased with litter age (F 45.36, P < 0.001, R2 0.19). Females who moved their litters from the primary natal den tended to receive more (t -1.99, P 0.08, df 8) male visits/night before their move, than females that stayed in the primary natal den. Males also visited natal den trees more often (t 2.26, P 0.05, df 7) when a natal family was occupying the den tree than once the family had stopped using the den tree. We were unable to examine den trees that were abandoned by their mothers, but our data suggested that female raccoons are intolerant of adult males at natal dens while raising their litters. This may be a response to the risk of male-driven infanticide. © 2010, American Midland Naturalist.


Thieme J.L.,Ohio State University | Rodewald A.D.,Ohio State University | Brown J.,Max McGraw Wildlife Foundation | Anchor C.,Forest Preserve District of Cook County | Gehrt S.D.,Ohio State University
Natural Areas Journal | Year: 2015

The proximity of urban green spaces to anthropogenic food sources can promote high densities of predators that may negatively affect breeding birds. Not only can high numbers of predators depress reproduction and survival, but birds may behaviorally respond by avoiding those patches, thereby diminishing the value of urban habitats. During 2010 and 2011, we examined relationships between avian territory density and activity of nest predators in 36 2-ha plots within six urban grassland and early successional parks (sites) near Chicago, Illinois. At the plot (i.e., local) scale, densities of common yellowthroats (Geothlypis trichas), field sparrows (Spizella pusilla), and savannah sparrows (Passerculus sandwichensis) were more strongly linked to habitat characteristics than predators. Song sparrow (Melospiza melodia) and eastern meadowlark (Sturnella magna) densities were not associated with habitat at the plot scale, but together were negatively related to activity of avian predators. Surprisingly, densities of song sparrows were positively associated with snake activity at both plot and site (i.e., landscape) scales, and densities of savannah sparrows increased moderately with activity of mesopredators at the site scale. Our results suggest that although habitat structure is a strong predictor of grassland bird densities in this urban matrix, activity of predators also may contribute to patterns of territory selection of certain bird species. With this in mind, managers encouraging settlement of grassland birds within urban preserves may consider (a) increasing dense groundcover that provides protective cover for songbirds, and (b) discouraging activities that promote activity of avian predators, particularly corvids.


Kristen Page L.,Wheaton College at Illinois | Delzell D.A.P.,Wheaton College at Illinois | Gehrt S.D.,Ohio State University | Gehrt S.D.,Max McGraw Wildlife Foundation | And 5 more authors.
Journal of Wildlife Diseases | Year: 2016

Baylisascaris procyonis, the raccoon (Procyon lotor) ascarid, is a common roundworm parasite of raccoons that is also a well-recognized zoonotic pathogen, and a cause for conservation concern. The transmission dynamics of B. procyonis differ with host population attributes, season, and landscape. We examined how the parasite’s population attributes change with season, parasite population structure, and host demographics. We examined 1,050 raccoon gastrointestinal tracts collected from 1996 to 2012. Of the 1,050 raccoons necropsied, 382 (36%) were infected with at least one B. procyonis (x=15.8 [95% confidence interval=13.39–18.26]; median=7; range 1–199 worms/host), and populations were overdispersed. There was a seasonal change in prevalence with a peak in October/ November. Worm burdens decreased approximately 28% per month from January to June and increased approximately 31% per month from June to December. The sex structure of B. procyonis populations was female-biased (56% female). Host demographics did not impact parasite population attributes. This study provides evidence that B. procyonis populations exhibit a yearly cycle of loss and recruitment that may impact the transmission dynamics of the parasite. © Wildlife Disease Association 2016.


Gehrt S.D.,Ohio State University | Gehrt S.D.,Max McGraw Wildlife Foundation | Wilson E.C.,Ohio State University | Brown J.L.,Max McGraw Wildlife Foundation | Anchor C.,Forest Preserve District of Cook
PLoS ONE | Year: 2013

Free-roaming cats are a common element of urban landscapes worldwide, often causing controversy regarding their impacts on ecological systems and public health. We monitored cats within natural habitat fragments in the Chicago metropolitan area to characterize population demographics, disease prevalence, movement patterns and habitat selection, in addition to assessing the possible influence of coyotes on cats. The population was dominated by adults of both sexes, and 24% of adults were in reproductive condition. Annual survival rate was relatively high (S=0.70, SE=0.10), with vehicles and predation the primary causes of death. Size of annual home range varied by sex, but not reproductive status or body weight. We observed partitioning of the landscape by cats and coyotes, with little interspecific overlap between core areas of activity. Coyotes selected for natural habitats whereas cats selected for developed areas such as residences. Free-roaming cats were in better condition than we predicted, but their use of natural habitat fragments, and presumably their ecological impact, appeared to be limited by coyotes through intraguild competition. © 2013 Gehrt et al.

Loading Max McGraw Wildlife Foundation collaborators
Loading Max McGraw Wildlife Foundation collaborators