FACTORS INFLUENCING MORTALITY ASSOCIATED WITH THE TRANSLOCATION OF NORTHERN RIVER OTTERS (LONTRA CANADENSIS) IN UTAH

摘要

Reintroductions and translocations of northern river otters have been a common management practice throughout the United States from the 1970s to the 2000s. Though many reintroductions have been successful, populations are not always monitored or evaluated post-release. From 2009 through 2012, we translocated 27 radio-marked otters into the Provo River watershed in northern Utah. Our objective was to determine what factors influenced the translocation-related mortality of otters. We developed a series of a priori models and used logistic regression to determine the most influential factors. We used Akaike's information criterion to evaluate relative model support. We found that the univariate model including body mass bore the most model weight and that body mass was the most important factor influencing the initial survival of translocated otters. Model-averaged b estimates indicated that otters at the high end of body mass were 4 times more likely to survive the translocation than otters at the low end of body mass. Sex was the next most important factor influencing survival, as odds ratios indicated that males were more likely to survive the translocation than females. We urge ecologists and managers to delay the trapping and translocating of otters until young-of-the-year are likely large enough to have a high probability of survival. We further recommend female-biased translocations, as females were less likely to survive translocations.