There are several goals of the river otter project. One is assessing year-to-year variations in population densities, primarily in the Jackson Lake Dam to Deadman's Bar section of the Snake River. Another is evaluation of habitat preferences on this section. A third objective is documenting behavioral reactions among otters and between otters and other species living in the riparian habitat. Finally, I wish to obtain a picture of the summer activity-cycle on a 24-hour basis.