The Influence of Weather on Reproductive Behavior and Population Trends of Four-toed Salamanders (Hemidactylium scutatum)​

Abstract

Environmental conditions influence amphibian reproduction, behavior, and development. Understanding these relationships is critical for developing effective management strategies to conserve populations and their habitats. However, knowledge gaps persist for many species, limiting our ability to predict responses to increasingly variable seasonal conditions driven by climate change. The first objective of this study was to further explain nest site fidelity in female four-toed salamanders (Hemidactylium scutatum) using photo-identification software (Hotspotter) to analyze individual ventral spot patterns. The second objective was to evaluate how seasonal weather patterns influenced the species' population abundance and trends over time at one site in Tennessee. I hypothesized that Hotspotter would accurately identify returning females and that females would exhibit nest site fidelity by returning to the same nesting area across multiple breeding seasons. To assess site fidelity, I used a Wilcoxon rank-sum test to compare re-nesting distances among individuals. To evaluate the effects of climate on reproduction, I examined the influence of daily maximum temperature, daily precipitation, and daily relative humidity on average clutch size and total annual nest abundance. Immediate and lagged climate effects were analyzed using a sliding window approach (1-48 months prior to nesting) within the R package climwin. I hypothesized that females would produce smaller clutches following unfavorable pre-nesting conditions and that the population would exhibit a recovery period of approximately two years. Results supported the site fidelity hypothesis, demonstrating that female-four-toed salamanders consistently rerun to the same or adjacent moss clump for oviposition. Climate analyses revealed that mid-fall to early-winter precipitation and early spring temperature in the year prior to nesting were the primary drivers of variation in clutch size, while only precipitation significantly influenced total annual nests. Our findings highlight the importance of long-term data for addressing knowledge gaps in nesting behavior and emphasize the need to protect critical habitat while continuing to collect data to better understand how four-toed salamanders may response to future environmental changes.