Behavior and detection method influence detection probability of a translocated, endangered amphibian

Accurate estimates of survival are crucial for many management decisions in translocation programs. Maximizing detection probabilities and reducing sampling biases for released animals can aid in estimates of survival. One important source of sampling bias is an animal's behavior. For example, individuals that are consistently more exploratory or active may be more likely to be detected visually. Behavioral traits can be related to survival after reintroduction, and because many pre-release treatments aim to manipulate animal behavior, it is critical to tease apart relationships between behavior and detection probability. Here, we assessed the repeatability (intra-individual consistency and inter-individual variation) of behavioral traits for an endangered amphibian, the mountain yellow-legged frog (Rana muscosa). Because new technological tools offer one potential solution for reducing sampling biases while increasing detection, we also tested whether a long-range passive integrated transponder (PIT) tag reader could enhance surveys for these individuals after translocation into the wild. After confirming thatex situbredR. muscosaexhibit repeatable behavioral traits (repeatability = 0.25-0.41) and releasing these frogs (N = 196) into the wild, we conducted post-release surveys visually and with the long-range PIT tag reader. Integrating the long-range reader into surveys improved detection probability four-fold in comparison to visual surveys alone (similar to 0.09 to similar to 0.36). Moreover, mark-recapture modeling revealed that tag reader detection probability was not biased toward detecting individuals of specific behavioral types, while visual detection was significantly related to behavioral traits. These results will enable a more accurate understanding of individual differences in post-release success in translocations. This may be particularly important for amphibian species, which can be difficult to detect and are expected to increasingly be involved in human-managed breeding and translocation programs due to their vulnerable conservation status.

Automated summary

Accurate estimates of survival are crucial for management decisions in translocation programs. Behavior can impact detection probabilities for released animals, highlighting the importance of understanding the relationship between behavior and detection probability. The use of a long-range PIT tag reader can significantly improve detection probability and reduce sampling biases compared to visual surveys alone.