The Impact of Management on the Movement and Home Range Size of Indiana's Eastern Hellbender Salamanders

Stewart Center 302

Eastern hellbenders (Cryptobranchus alleganiensis alleganiensis) are a large, fully aquatic salamander species distributed throughout watersheds in the eastern United States. In Indiana, hellbenders were once found in tributaries of the Ohio River and the Wabash River but are now restricted to a single river in the southern portion of the state. Monitoring within the Blue River over twenty years has revealed a steady decrease in the total abundance of hellbenders and a shift towards older individuals in the age structure of the population. Concerned over the apparent lack of recruitment, the Indiana department of natural resources performed a series of management actions to ensure the continued persistence of the species in the state. This included the translocation of 11 isolated adults and 10 captive-reared juveniles to two sites within the river in order to increase local densities. Both resident and translocated adults were tracked for two years while juveniles were tracked for 10 months via radio telemetry to assess movement patterns. Using a series of generalized linear mixed models we examined how these management actions affected movement probability, movement distances, and home range size over time. We found that both probability of movement and movement distances decreased at higher site densities. However, translocated individuals moved greater distances than residents leading to larger home range sizes particularly in naive juveniles. These findings are important since increased movement may be associated with lower probability of survival due predation or flood events.