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Description
The mountain yellow-legged frog (Rana muscosa) has a disjunct distribution spread between the Sierra Nevada and southern California. The southern California population of mountain yellowlegged frog (MYLF) is recognized as a distinct population segment, and with less than 200 adults remaining in the wild, is protected under the federal endangered species act. I examined multiple facets of MYLF conservation across both wild and captive populations with the goal of improving current conservation efforts for the species. To understand the microhabitat needs of the MYLF I modeled the relationship between MYLF presence and 11 microhabitat variables on a per pool scale. Logistic regression models with Akaike's Information Criteria (AIC) were created for both frog and tadpole life stages. The frog model revealed that pool volume, pool leaf litter, bank leaf litter, and understory cover were important variables associated with frog presence. The tadpole model indicated that pool depth and understory cover were important and that pH was marginally important. This knowledge of the microhabitat needs of the MYLF can improve reintroduction efforts by allowing managers to make more informed decisions about where the MYLF should be reintroduced. To improve the reproductive output of a captive colony of MYLF with a history of low reproductive success, I measured the effect of an artificial hibernation period on multiple reproductive behaviors. Males subjected to advertisement calls of conspecific males demonstrated an increased phonotaxic response after a hibernation period (P = 0.01). However, females did not demonstrate a change in phonotaxic response after hibernation (P = 0.93). Examining the reproductive behaviors of breeding pairs I found that males who were hibernated had significantly higher frequencies of amplexus (P < 0.01) and advertisement calls (P = 0.01). Females that were not hibernated produced more release calls (P = 0.05), indicating a lack of receptivity. Only females who were hibernated laid eggs. These results demonstrate the importance of hibernation for the expression of reproductive behaviors in the MYLF. Understanding the cues that influence habitat preferences is important for endangered species reintroduction efforts as these cues can potentially be manipulated to encourage settlement at specific locales. To understanding the effect of conspecific cues on MYLF habitat preferences captive male and female frogs were provided with two water sources, one water source was scented with chemical cues from adult females outside the breeding season and the other source was unscented. I did not detect a significant difference in the amount of time that males (P = 0.57) or females (P = 0.09) spent in either water source. This indicates that conspecific chemical cues from females outside of the breeding season do not influence MYLF habitat preferences. Finally, I tested the ability to use photo mark-recapture techniques to identify individual tadpoles in the wild. Most MYLF survey efforts focus on adult frogs, due in part to the difficulty in detecting tadpoles and obtaining data on population size. A better understanding of the population ecology of MYLF tadpoles is critical for recovery efforts because it is believed that population recovery is limited by the poor recruitment of tadpoles into the adult breeding population. The tadpole life stage is often understudied in population demographic studies of amphibians. I employed a mark-recapture study using photographs of tadpoles' natural spot patterns to determine if unique individuals could be re-identified in the wild. I determined that MYLF tadpoles could be re-identified using their unique natural patterns.
