Space Use and Habitat Selection by Bobcats in the Fragmented Landscape of South‐Central Iowa

Abstract

Historically, bobcats (Lynx rufus) were found throughout the Corn Belt region, but they nearly disappeared from this area due to habitat loss and unregulated harvest that occurred during the century after European settlement. Reports of bobcat occurrences have been increasing in Iowa, USA, and biologists would like to understand the mechanisms enabling bobcats to recolonize this fragmented agricultural landscape. We determined space use and habitat selection of bobcats by radiocollaring 68 bobcats in south‐central Iowa during 2003–2006. We triangulated 12,966 locations and recovered an additional 1,399 3‐dimensional locations from Global Positioning System collars. We used a fixed kernel estimator to calculate 95% utilization distributions (UDs) for home ranges and 50% UDs for cores. Annual home range area of males (x̄ = 58.6 km2, 95% CI = 49.2–69.9) was nearly 3 times that of females (x̄=19.9 km2, 95% CI = 17.0–23.3). Females used smaller home ranges during April‐September when they were suspected to have kittens with them (x̄ = 16.8 km2, 95% CI = 13.7–20.7), as compared to October‐March (x̄ = 24.1 km2, 95% CI = 19.0–30.7), whereas home ranges of males did not differ between seasons. Similarly, core area of males (x̄ = 7.7 km2, 95% CI = 6.2–9.6) was larger than that of females (x̄ = 2.3 km2, 95% CI = 1.9–2.7). Females used significantly smaller cores in April‐September (x̄ = 1.8 km2, 95% CI = 1.4–2.3) as compared to October‐March (x̄ = 2.8 km2, 95% CI = 2.2–3.7), whereas males did not. For both sexes, compositional analysis indicated that forest habitat was ranked higher than all other habitat classes at both the landscape and local scale. Standardized habitat selection ratios illustrate that female and male bobcats selected forest habitat about twice as frequently as any other habitat class, including grassland and Conservation Reserve Program land. Predictive models indicated that home range and core area was smaller in landscapes where perennial forest and grassland habitats were less fragmented. Predictive models indicated home ranges were more irregular in shape in landscapes where row crop patches were less aggregated within home ranges. Our results have practical implications for wildlife managers regarding expected bobcat habitat use and distribution as the species becomes more abundant in the agricultural landscape of the Midwest.

Mapping behavioral landscapes for animal movement: a finite mixture modeling approach

“…Male bobcats tend to have larger home ranges, move longer distances during the process of dispersal, and exhibit greater competition for space, which makes encounters with roads and urban areas more likely (Sandell 1989, Sunquist and Sunquist 1989, Janecka et al 2006, Tucker et al 2008. Studies of bobcat behavior in California suggest that there is either no difference in male vs. female bobcat use of urbanized areas or that females cross roads and use urbanized areas less than males ).…”

Habitat modeling used to predict relative abundance of bobcats in Iowa

“…Nearly all studies of bobcat habitat relationships have concluded that bobcat presence and abundance is influenced by the distribution and characteristics of forested habitat (Woolf et al 2002, Preuss and Gehring 2007), especially at the local scale (Lovallo et al 2001, Constible et al 2006, Tucker et al 2008). However, our analyses and modeling highlight that the quantity and configuration of other habitats, especially perennial grassland cover in association with woodlands, predicted relative abundance of Iowa bobcats at the county scale.…”

“…We also calculated metrics at the landscape level, representing the structure of the landscape mosaic, regardless of habitat class (Constible et al 2006). Past research suggested that Iowa bobcats selected forest habitat in their home range twice as often as predicted by random chance, grassland and CRP approximately equal to random chance, and row crop much less than random chance (Tucker et al 2008). Consequently, we assigned edge between forest and row crop a high contrast (0.8), edges between forest and grassland and forest and CRP a moderate contrast (both 0.5), and edge between grassland and CRP a low contrast (0.1).…”

“…Bobcats are most often associated with woodland habitats (Anderson and Lovallo 2003), but also occupy more open landscapes comprised of bluffs and brushy habitat where there is adequate stalking cover (Hamilton 1982, Koehler and Hornocker 1991). They are generally not a species of open grasslands (Anderson and Lovallo 2003) although it is reasonable to hypothesize that changes in the agricultural landscape associated with the Conservation Reserve Program (CRP) might have improved habitat for bobcats (Tucker et al 2008). Bobcats are adaptable and can be found in suburban habitat with dense cover even though they avoid humans (Riley et al 2003, Roberts et al 2010).…”

Can Orchards Help Connect Mediterranean Ecosystems? Animal Movement Data Alter Conservation Priorities

“…I used compositional analysis methods (as in Chamberlain et al 2003 andTucker et al 2008) to estimate the ratio of used to available habitat for each collared bobcat at three levels: home range to available habitat, core to available, and core to home range. I used a paired t-test to test whether the percent of avocado orchard in the used and available habitats differed.…”