Generic-to-Nuanced Gradient of Response to Anthropogenic Change
Taken altogether, these results support the idea that bobcats and coyotes are at different ends of the generic-to-nuanced response gradient. Bobcats exhibited a “broad-stroke”, generic response to human modification. When faced with human modification, bobcats expanded their home ranges and functionally responded in their selection in a predictable manner with little temporal variation and complexity in their resource selection overall. These results corroborate previous work that shows that bobcats avoid humans (e.g., Reilly et al. 2022) and rely on corridors across a development gradient (Popescu et al. 2021, Mayer et al. 2022). In contrast, human modification did not affect coyote home range size, but it did cause coyotes to have more temporally-acute resource selection behaviors and varied and complex functional responses in their resource selection, which often changed temporally in intensity or direction. Compared to bobcats, coyotes were able to fine-tune their spatial behavior by avoiding the aspects of human modification that were disadvantageous on a finer scale within their home range instead of expanding their range. While it might be unanticipated that a species adapted to coexistence with humans would avoid human modification, this avoidance of human-associated areas (Gosselink et al. 2003) is a part of their adjustment strategy. Coyote temporal adjustments have been documented, including changing habitat preferences on a daily scale to avoid risk (Petroelje et al. 2021, Rivera et al. 2021) and on a seasonal scale to exploit seasonal resources (Webster et al. 2022). The overall nuance of coyote response to human modification illustrates how a species’ response to novel environments can occur on multiple scales. These responses highlight differences in population-level plasticity between the two species.
Focusing on multiple aspects of space-use by investigating home-ranging behaviors and resource selection including spatial, temporal, and individual variation allowed us to reveal the complexity and differences in mesocarnivores’ responses to anthropogenic disturbance. While investigating functional responses in resource selection is becoming more common (Godvik et al. 2009, Herfindal et al. 2009), investigating temporal variation in these functional responses is rarely done, yet considering this aspect is critical in understanding the degree of nuance in spatial behavior. However, using these characteristics allowed us to develop the generic-to-nuanced gradient, a framework where we can categorize species based on several spatial behaviors and highlight how a species is responding to anthropogenic change. Finding where a species or population falls along the generic-to-nuanced gradient described here can have important conservation and management implications. As human modification continues, understanding the full extent of its effects on wildlife population dynamics and fitness (Webber et al. 2020) as a result of individual- and population-level responses is increasingly crucial. Species that are less plastic are more likely to be disadvantaged in high-disturbance environments, while behavioral flexibility leads to increased success and tolerance of anthropogenic environments (Lowry et al. 2013, Lovell et al. 2022). For example, bobcat populations in North America only recently began recovering after record lows in the 1900’s (Roberts and Crimmins 2010), while coyote populations have both increased in number and range across North America with anthropogenic land changes and extirpation of large predators (Linnell and Strand 2000, Laliberte and Ripple 2004), illustrating the implications of species-level plasticity and tolerance to human modification. However, while a nuanced response to human modification can provide benefits in exploiting anthropogenic habitat, there are also risks associated with this behavior. Forty-two percent of the coyotes in this study (n =13) were killed (hunted or trapped) within one year after being collared. While coyote abundance in this population appeared to remain stable despite these mortalities, it remains that there is a risk to individuals coexisting with humans.
The gradient of nuance in spatial response described here could be used as another metric to predict how species will react to future changes, and potentially as how best to manage them. Rettie and Messier (2000) proposed the “hierarchy of limiting factors” hypothesis, stating that species will display space-use response at a broader scale to address their most limiting factors. Similar to this idea, species on the generic end of the spectrum appear to respond to human development by displaying broad spatial response, indicating that habitat itself might be their biggest limiting factor (Rettie and Messier 2000). As such, managing species like bobcats should focus on habitat manipulation to mitigate blanket responses in home range size and habitat selection. Species on the nuanced end of the spectrum, like coyotes, may respond more to factors impacting the type of interactions with humans, such as harvest management, because they can be more flexible in habitat use and risk avoidance on a temporal scale. In such, our generic-to-nuanced framework highlights the importance of investigating spatial, temporal and individual responses to elucidate how other species might be impacted by human activities and how to best mitigate these activities.