Dietary differences between male and female river otters : evaluation with non-invasive genetic sampling

Several studies have shown that there are vast differences in dispersal, space use, social interactions and foraging habits between male and female coastal river otters (Lontra canadensis). Such differences have significant effects on the dynamics of otter populations and gene flow. Because male otters travel long distances in search for fish schools, they may be less affected by local conditions, such as oil contamination. In contrast, females, who are more sedentary and spend time close to dens and young, may be more susceptible to such adverse conditions. Because adult female survival is the most important factor affecting population persistence, evaluation of sex ratio and dietary differences between the sexes may shed light on the status of this component of the population. We used DNA analyses to determine the sex of 261 fecal samples collected in Prince William Sound, Alaska, in 2006. Those samples that were successfully sexed and contained identifiable prey remains were sent to Pacific ID for diet analyses. Here we report our results on sex ratio and dietary differences between the sexes and discuss their meaning for the persistence of the population.