Forest Preserve District of Cook County

Elgin, IL, United States

Forest Preserve District of Cook County

Elgin, IL, United States
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Nixon C.M.,Illinois Natural History Survey | Mankin P.C.,Urbana University | Hansen L.P.,Columbia College at Missouri | Brewer P.A.,660 West Polk Ave | And 2 more authors.
American Midland Naturalist | Year: 2010

This study of dominant and subordinate led social groups of white-tailed deer (Odocoileus virginianus) was designed to investigate longevity and associations among members as well as the reproductive success that determines the durability of these groups. Characteristics of 25 dominant and 17 subordinate female led social groups of white-tailed deer were studied on three areas in Illinois. Group size for dominant led social groups ranged between 3.8 and 5.2 deer/y and for subordinate led groups only 22.5 deer. Dominant females survived significantly longer (8.2 y) then did subordinate females (5.4 y) and fawns born to dominants were significantly more sedentary after independence. Fawn recruitment (fawns alive at 1 y) was also significantly higher for fawns born to dominant females. Members of a dominant female's social group generally confined themselves to the home range of the dominant female but as they aged were seen less often with her. Dominant females occupied stable habitats free of environmental problems while subordinates occupied ranges with frequent natural and human induced disturbances. By association, fawns of dominant females inherit a stable home range that fosters improved longevity and successful fawn recruitment © 2010, American Midland Naturalist.


Bowles M.L.,Morton Arboretum | Lawrence B.A.,DePaul University | Lawrence B.A.,University of Connecticut | Antlitz D.J.,Forest Preserve District of Cook County
Journal of the Torrey Botanical Society | Year: 2017

Formerly widespread Midwest savannas have become a rare vegetation type mainly due to fire exclusion and development of fire resistance as trees increase in size. As a result, restoration management including burning and thinning is a high conservation priority. We examined temporal changes in a thinned and fire-managed mesic oak savanna remnant in the Chicago region of northeast Illinois. Before 1960, this remnant was structured with an open canopy and apparently an oak grub layer. It was initially sampled in 1995 after near canopy closure due to fire exclusion, and was resampled in 2013-14 after management. Burning did not increase canopy openness. We asked how thinning to increase canopy openness affected ground layer diversity at multiple scales and whether species light adaptations and traits could predict responses to thinning. Thinning reduced stem density and increased canopy openness to > 30%, but also reduced canopy heterogeneity as large canopy gaps were not restored. Alpha diversity increased significantly due to increases in density and cover of light-Adapted rhizomatous woodland species. Beta diversity declined, reflecting reduced canopy heterogeneity and decline of shade-Adapted species. Gamma diversity of light-Adapted woodland species also increased. Despite close proximity of a species pool of C4 grasses and prairie forbs, a truncated canopy light gradient apparently prevented increases in these shade-intolerant species. Oak sprouts from cut stumps appear to be capable of regenerating a grub layer. Management implications include the need to apply additional thinning to further increase canopy openness and heterogeneity as well as diversity of ground layer vegetation at multiple scales, and to apply frequent fire to maintain an oak grub layer and enhance herbaceous species establishment. © Copyright 2017 by The Torrey Botanical Society.


Gehrt S.D.,Ohio State University | Kinsel M.J.,University of Illinois at Urbana - Champaign | Anchor C.,Forest Preserve District of Cook County
Journal of Wildlife Diseases | Year: 2010

Parasites have the potential to influence the population dynamics of mammalian hosts, either as a single devastating pathogen or as a community effect. Striped skunks (Mephitis mephitis) are typically host to rabies, which often regulates population numbers. We assessed micro- and macroparasite dynamics in striped skunk populations in the absence of rabies, to determine if a single pathogen, or community, was responsible for a majority of skunk deaths. We monitored mortality due to pathogens, and prevalence of pathogens via serology and necropsy, in two populations of striped skunks in northern Illinois during 1998-2004. Transmissible pathogens requiring direct transmission (i.e., canine distemper virus, canine parvovirus) exhibited high annual variability in prevalence. In contrast, those pathogens employing a more indirect, environmental route of transmission (i.e., Leptospira interrogans and Toxoplasma gondii) appeared to exhibit relatively less annual variability in prevalence. Skunks were diagnosed with infections from an average of 4.08 (SD=2.52, n=32) species of endoparasites, with a range of 1-11. Macroparasite prevalence and intensity did not vary among seasons, or sex or age of host. Severe infections occurred with multiple parasite species, and patterns of aggregation suggested some parasite species, or more likely the parasite community, act as a limiting mechanism in skunk populations. © Wildlife Disease Association 2010.


Piccolo B.P.,717 North Roscommon Road | van Deelen T.R.,University of Wisconsin - Madison | Hollis-Etter K.,Urbana University | Etter D.R.,562 East Stoll Rd | And 2 more authors.
Canadian Journal of Zoology | Year: 2010

Neonatal survival influences growth of unhunted populations of suburban white-tailed deer (Odocoileus virginianus (Zimmerman, 1780)). Understanding the interaction of habitat and survival may inform conservation efforts and studies of life history of cervids at high density. We chose two forest preserves representative of forests in suburban Chicago. We radio-marked 56 neonates (1999-2001) to investigate mortality and habitat use. Through 1 July, 21 of 29 (72%) neonates and 6 of 22 (27%) died mostly because of predation by coyotes (Canis latrans Say, 1823). Akaike's information criterion suggested that optimal mark-recapture models of survival contained covariates reflecting differences by preserve and timing chosen to coincide with behavioral change from hiding to accompanying the doe. Survival was lower during early parturition (0.26-0.78) relative to the latter part (0.90-0.96). Early fawns (hiders) at one site had lower survival (0.26-0.29) than fawns at the other (0.78). Lower survival associated with larger home ranges, greater movement, and reduced understory cover, suggesting that hiding cover may mediate fawn survival in the presence of predators. Our study demonstrates spatial heterogeneity in population biology of suburban deer and suggests that site-specific differences may influence neonate survival in the face of coyote predation.


Graser III W.H.,Ohio State University | Gehrt S.D.,Ohio State University | Hungerford L.L.,University of Maryland Baltimore County | Anchor C.,Forest Preserve District of Cook County
Journal of Wildlife Management | Year: 2012

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 (F2,17 = 4.66, P = 0.027): urbanized sites, ̄x = 4.96 ± 2.64 raccoons/km2, range = 1.25-10.00 raccoons/km2; urban open sites, ̄x = 14.84 ± 6.35 raccoons/km2, range = 3.00-29.25 raccoons/km2; rural open sites, ̄x = 15.50 ± 4.66 raccoons/km2, 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. Copyright © The Wildlife Society, 2012.


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.

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