North American river otters (Lontra canadensis) were endemic throughout much of North America. However, overexploitation and anthropogenic degradation of habitat resulted in population declines in much the southwestern United States. Recently river otters have been reintroduced to many states in the southwest, including Colorado. Monitoring otter populations and reintroduction success is difficult due to the animal's elusive nature. This study examines several biological aspects of a reintroduced river otter population in Colorado. Chapter one describes a modified body-snare and a modified foot-hold trap developed to obtain hair DNA from otters. DNA analysis of these hairs can lead to otter population estimates and a measure of geneflow between otter reintroduction sites. Our traps were 94% effective capturing hair and capture rates ranged from 1 capture per 3.6 trap nights to 1 capture per 156.6 trap-nights. This chapter is formatted for and published in the Journal of Wildlife Management (71:671-674; 2007). Chapter two is formatted for the Journal of Mammalogy and is the first study to date to document river otter latrine site selection in arid environments. Because river otters use latrine sites as intraspecific communication posts our model will give managers a tool to evaluate otter distribution, range expansion, and persistence of existing, or reintroduced otter populations. Otters selected latrine sites with the presence of beaver activity, on large prominent rocks, adjacent to deeper water, with shading over the site, and rock or cliff overstory. Finally chapter three is formatted for Conservation Biology and examines population structure of a reintroduced river otter population in Colorado. Otters had limited geneflow between two study sites that are only 45 km apart. Our data suggest that some environmental factor is restricting otter movements between these study sites. Failure to ensure corridor habitats are suitable for otter movements could result in a reduced rate of range expansion and even lead to local extirpation. The research presented here will provide wildlife professionals the tools to efficiently locate otter use sites, set remote DNA hair traps, and provide a guide for river otter reintroduction locations.