Evaluating the efficacy and decay of lures for improving carnivore detections with camera traps

Abstract Abundance and occupancy estimates are essential to wildlife research, but are often hampered by limited detections, especially for cryptic species like carnivores. While scientists can account for limited detections during statistical analyses, increasing detections in the field is the best way to reduce uncertainty. Camera traps are an effective, noninvasive method of monitoring wildlife, and using attractants with camera traps can increase the likelihood of detecting carnivores. We tested two scent lures (sardines and fatty acid tablets) against a control of no lure to determine whether either lure increased detections of six carnivore species, bobcat (Lynx rufus), coyote (Canis latrans), gray fox (Urocyon cinereoargenteus), raccoon (Procyon lotor), striped skunk (Memphitis memphitis), and ringtail (Bassariscus astutus). We also examined how detection of carnivores was affected as the lure decayed over time. We used occupancy modeling for each species to determine whether either lure increased detection probability. We then modeled how lure decay affected carnivore detections and determined the optimal length of deployment using generalized linear mixed models. Sardines increased detections across all carnivores, but also had a high rate of decay and were no different than the control at day 18. Fatty acid tablets decayed more slowly, but were not significantly different from the control at any point. Among species, detections of gray foxes and raccoons increased with both sardines and fatty acid tablets, while detections of ringtails increased only with sardines, and other species did not respond significantly to either lure. Our analysis shows that lures can increase detections of carnivores, but species‐specific responses and study objectives must be considered when choosing a lure. These results will allow future researchers to improve the accuracy of abundance and occupancy estimates through increased detections of difficult to study species which ultimately leads to better conservation and management of those species