How competitive intraguild species coexist remains a fundamental question in ecology. We sought to study the phenomenon of temporal niche partitioning between two carnivore species in northern Michigan, raccoon (Procyon lotor) and coyote (Canis latrans). Raccoon, a common mesopredator, has been found to utilize spatial and diet partitioning in some habitats to avoid competition with coyote. When these niches do coincide, we hypothesized that raccoon would change activity patterns to avoid direct competition with coyote and that temporal partitioning may act as a driver for coexistence. From October 2015 to January 2016 we conducted an 11-week camera trapping survey of 56 cameras at the University of Michigan Biological Station (Pellston, MI), encompassing 4,367 trap nights. We studied the activity patterns and overlap of time by raccoons against coyote among three ‘zones’ of coyote activity (low, medium, and high), as well as between raccoons in each zone. Using metadata extracted from our camera trap photos and the ‘Overlap’ package in R, we applied a kernel density estimator underneath a time graph. With these estimators, we produced a measure of pairwise overlap between groups as a probability distribution centered around a coefficient of overlapping Δ which ranged from 0 (no overlap) to 1 (total overlap). In addition, we examined temporal partitioning as a function of activity frequency across diel periods by separating triggers of raccoon activity into three main groups: diurnal, nocturnal, and crepuscular (sunrise +/- 2 hours and sunset +/- 2 hours).
When comparing activity with the overlap package over a 24-hr scale, we found coinciding confidence intervals in pairwise comparisons between raccoon and coyote and among raccoons. This may indicate that temporal partitioning is not utilized by raccoons here – suggesting that sympatry with coyote has precipitated other coexistence strategies. However, when comparing diel period activity between the same zones, we found a significant increase in crepuscular behavior among raccoons in areas of high coyote activity when compared to zones of both low (p = 0.0019) and medium coyote activity (p = 0.004), but no significant difference between areas of low and medium coyote activity (p = 0.396). Studies suggest that raccoons are primarily active during nocturnal hours, while our findings may indicate that the presence of a dominant competitor drives a shift towards more transitional hours around sunrise and sunset. Effective carnivore management necessitates an understanding of species interactions and how subordinates respond to activity of dominant competitors.