Species-specific responses to survey design are an important consideration in camera trap studies. A new paper published in Wildlife Biology by Fabiola Iannarilli and colleagues aims to bring clarity to design tradeoffs in camera-trap surveys for medium-to-large carnivores in the midwestern United States. The authors explored species-specific responses to multiple different strategies:
1. Survey design (random versus road-based),
2. Lure types (salmon oil versus fatty acid scent oil),
3. Camera placement strategy (completely random versus randomly-selected sites with feature-based (i.e. deer trails to maximize the probability of carnivore detection) placement),
4. Timing of data collection (spring versus fall), and
5. Temporal trends in daily encounter probabilities.
They found strong, species-specific responses to different survey design strategies; species that were similar in size and closely related responded differently to design choices! For example, the presence of salmon oil quadrupled coyote detection, doubled encounters of wolves, gray foxes, American martens, and striped skunks, yet had no significant effect on bobcats, raccoons, and red foxes, as compared to fatty acid scent oil. While researchers might assume equal and constant detection probabilities across species, these findings highlight that comparisons across time, space, and species must consider survey design. The authors recommend that researchers carefully consider species-specific responses to different aspects of survey design and suggest that a hybrid, mixed survey strategy may improve encounter probabilities when the goal is to maximize data collection for multiple species across the landscape. They also emphasize that further pilot testing of survey design is recommended to better inform targeted guidelines for applied wildlife monitoring programs.
By Isla Francis