AUTHORS: Max R. Larreur, Southern Illinois University; Clayton K. Nielsen, Southern Illinois University; Damon B. Lesmeister, USDA Forest Service, Oregon State University; Guillaume Bastille-Rousseau, Southern Illinois University
ABSTRACT: Broad ecological changes can alter species' temporal activity, thereby impacting interspecific interactions. Temporal niche separation promotes coexistence, causing species to adjust activity patterns to avoid direct competition. Although studying carnivore species offers a unique perspective into the stability of their temporal activity and niche, few analyses have been conducted over long-term periods in areas experiencing conspecific population changes. We quantified species-specific and pairwise temporal activity patterns, using kernel density analysis overlap, for 6 native (i.e., bobcat, coyote, gray fox, red fox, striped skunk, and raccoon) and 2 non-native (i.e., domestic dog and cat) carnivore species along with their diel niche between decades. We used camera trap data collected January – April 2008 – 2010 (n = 1,118 camera locations) and January – April 2022 – 2024 (n = 1,325 camera locations) across 16,058-km2 of southern Illinois to identify potential changes in temporal overlap or niche separation between decades. Species-specific activity overlap was high (range = 0.81 - 0.95) between decades, however, activity patterns of striped skunk, raccoon, and domestic dogs were different. Both past and contemporary pairwise comparisons had 6 activity patterns indicating potential avoidance between larger-bodied and smaller-bodied guild members, and 7 activity patterns indicating potential avoidance between native and non-native carnivore species. However, 7 novel pairwise activity patterns have experienced significant changes from the past, 3 between natives and 4 between natives and non-natives. The diel niche of bobcat, gray fox, red fox, and striped skunk indicated minor changes in their diel activity potentially in response to larger-bodied coyote and domestic dog spatial presence throughout the study area. Larger-bodied carnivore species may be altering activity patterns of smaller-bodied members, thereby decreasing competition and negative interspecific interactions. Our results emphasize the importance of considering alterations to activity overlap and potential niche separation amongst carnivores with high resource overlap and propensity for interspecific interactions.
