Testing the Efficacy of Protected Areas: Use of Protected Activity Centers by GPS-Tagged Mexican Spotted Owls

Protected areas play an important role in wildlife conservation, yet evaluating their effectiveness can be difficult. We assessed the efficacy of protected areas for Mexican Spotted Owls (Strix occidentalis lucida) by examining how federally designated Protected Activity Centers (PACs) and nest cores aligned with true Mexican Spotted Owl space use for roosting and foraging. We also examined if Mexican Spotted Owls used multiple PACs—a behavior commonly observed in California Spotted Owls (Strix occidentalis occidentalis)—and how Mexican Spotted Owl home range size compared to PAC size. We GPS tagged 22 owls from April through August 2023 across two study areas in the southwestern United States. PAC and nest core use was high, with over half (58%) of nocturnal foraging locations and 92% of diurnal roosting locations within PACs. Mexican Spotted Owls spent little time in other PACs outside of their home PAC, with most owls using just one PAC exclusively. Breeding season 75% kernel density home range estimates closely approximated Mexican Spotted Owl PAC size; however home ranges varied greatly among individuals based on sex, study area, and breeding status. Our research adds to that of previous studies showing Spotted Owls use PACs extensively, suggesting PACs are adequately protecting critical nest, roost, and foraging habitat for this species. However, we also observed a range of individual variation, emphasizing the importance of allowing protected area boundaries to be dynamic rather than static within a rapidly changing world.