OCCUPANCY MODELING OF ISLAND SPOTTED SKUNKS

Desirae E Thomaier; Cal Poly SLO; desthomaier@gmail.com; Juliann Schamel, Lara Brenner, David Jachowski, John Perrine, Tim Bean

The island spotted skunk (Spilogale gracilis amphiala) is a rare, cryptic mesocarnivores endemic to Santa Rosa and Santa Cruz Islands, part of the California Channel Island archipelago. During the near-extinction of the sympatric island fox via predation by invasive golden eagles, island spotted skunk populations increased significantly. Now island foxes have recovered on these islands and skunks seem to have precipitously declined - potentially due to interspecific competition with foxes, who have a larger body size and broader temporal and dietary niche. We suspect that skunks now have low abundance on both islands. We are investigating island-wide occupancy via year-round camera surveys on both islands, with cameras placed in drainages to maximize detectability of this small mesocarnivore. We installed 92 cameras in the summer of 2023 and will maintain them for one year. Preliminary data suggests that skunks have low rates of occupancy across both islands, and differential rates of occupancy are associated with topographic, environmental, and interspecific interaction-level differences across sites. This study helps address a time-sensitive question of how island spotted skunk populations are responding to high fox abundance, and could be used to inform future studies, conservation, and management on the Channel Islands.

Channel Islands Conservation   Student Paper