Predator Spatial Behavior and Response to Human Modification
While sex had no effect on bobcat home range size, study site did have a significant effect. Overall, increased levels of human modification within home range was correlated with larger home range size in bobcats. Bobcats tend to use larger home ranges in more fragmented and developed landscapes (Riley et al. 2003, Tucker et al. 2008) and lynx (Lynx lynx ) have been found to expand their home ranges in order to increase hunting efforts in areas with declining prey abundance (Schmidt 2008). Therefore, the fragmentated, patchy landscape and increased human modification in the central Illinois site could be leading to low-quality forage for bobcats, causing them to expand their home ranges to maintain access to necessary resources (Reding et al. 2013, Nielsen et al. 2017). Coyotes had larger home ranges than bobcats, but a large amount of variation was present within the coyote population (Gese et al. 1988, Grinder and Krausman 2001). Sex and study site accounted for some of that observed variation, but neither had a significant effect on home range size. Other coyote populations have increased home range size with more forest cover (Ellington and Murray 2015), but coyote home ranges in this study were unaffected by the large difference in forest cover between the two study sites. In addition, there was no correlation between human modification within their home ranges and home range size in coyotes. This lack of response is likely due to coyotes adapting to human modification in their home ranges in other ways, such as spatial choices within their home ranges (Gehrt et al. 2009) or temporal adaptations to human activity (Gaynor et al. 2018, Shamoon et al. 2018).
Coyotes displayed a higher degree of temporal adjustment in their resource selection coefficients than bobcats; their responses were more varied depending on the temporal period, both diel and by season, than bobcats. We observed bobcat tolerance of human modification and exurban habitat regardless of temporal period, which was unexpected based on previous studies (e.g., Reed et al. 2017). Bobcats could be diluting the human density within their home ranges by expanding their home ranges in response to human modification, becoming less negatively affected by human modification and exurban areas overall. This dilution is possible as long as human use is below a certain intensity (Nielsen and Woolf 2001, OrdeƱana et al. 2010).
Bobcats and coyotes both adjusted their responses to agriculture, exurban habitat, and water depending on the degree of human modification around them. Bobcat functional responses to human modification in their home ranges were straightforward, selecting more agriculture, less exurban habitat, and areas closer to water as human modification increased. This means that human modification does impact bobcat behavior, causing them to adjust their use of habitat accordingly, which was expected (Flores-Morales et al. 2019). The directionality of these trends was consistent when they were present regardless of the temporal period, although the strength of the trend sometimes varied by temporal period. Coyotes had a more varied response to human modification, and cumulative (mean) annual responses did not always reflect trends in individual temporal periods. In addition, regressions were sometimes quadratic and changed direction after a threshold of human modification. Overall, coyote functional responses to human modification were more nuanced and temporally-acute than those of bobcats.