An evaluation of survey techniques for determining relative abundance of river otters and selected other furbearers.

Abstract

Four survey techniques for determining relative abundance of river otters (Lutra canadensis) in east-central Kansas were evaluated in 1986. Scent station surveys and sign surveys were conducted on stream segments and at bridge sites. Survey indices were derived by dividing the number of visits by the number of survey0nights, then multiplying by 10. The numbers of survey-nights for the stream segment scent station survey, the stream segment sign survey, the bridge site scent station survey, and the bridge site sign survey were 200, 100, 200, and 100, respectively. The number of survey-nights for otters was 50% of the total. River otter survey indices were highest at bridge sites with visitation indices of 4.20 and 4.40 for the scent station survey and the sign survey, respectively. There was no significant difference (P > 0.05) between visitation rates at paired scent stations and sign survey areas for river otters. Survey indices for raccoons (Procyon lotor) were highest in the bridge site surveys and the sign surveys. The bridge site sign survey produced the highest index of 9.00. Bridge site scent station surveys and stream segment sign surveys each yielded indices of 7.00. There was a significant difference (P < 0.05) between visitation rates at paired scent stations and sign survey areas for raccoons. The bridge site sign survey produced the highest index (1.50) for mink (Mustela vison), and beaver (Castor canadensis). The results of this study indicate that bridge crossing sign surveys and bridge crossing scent station surveys may be effective methods for determining relative abundance of river otters and raccoons in eastern Kansas.