Influence of husbandry and habitat design on Japanese giant salamander (Andrias japonicus) behavior and space use

Abstract Complex, appropriately sized, and enriching environments that promote the expression of species-appropriate behaviors have been associated with positive welfare outcomes for many taxa. However, amphibians remain one of the least represented taxa in zoo research, contributing to a chronic deficiency in available information. This study monitored the behavior and space use of five adult Japanese giant salamanders (Andrias japonicus) housed at the Detroit Zoo’s National Amphibian Conservation Center (NACC) in relation to husbandry practices and habitat complexity. In 2017, the salamanders were moved to a new habitat featuring a substantial increase in space and naturalistic structures. During this process, staff recorded daily husbandry information (e.g., water temperatures, habitat cleaning) and conducted individual-level assessments of behavior and space use. In 2022, the habitat underwent minor modifications focusing on cave expansion. Throughout this process, staff conducted group-level rapid assessments of behavior, exposure, social proximity, and space use. Ultimately, analysis of the 2018 data focused on the influence of husbandry on behavior, while the 2022 data focused on the role of increased habitat complexity. Individuals increased activity and reduced food consumption seasonally, potentially in response to shifts in water temperature or photo period. Following the 2022 cave modifications, individuals increased use of the expanded caves and decreased use of shallow nooks and overhangs. These results suggest that subtle changes in salamander environmental conditions, as well as increased space and provision of naturalistic hide structures, can result in positive shifts in appropriate species-specific and welfare-relevant behavioral proxies. However, further study is needed to identify and validate amphibian behavioral and affective indicators of welfare.