Natural Resources, School of

 

First Advisor

Dr. Craig Allen

Date of this Version

Fall 11-28-2016

Citation

Bieber, N. R. 2016. River otter (Lontra canadensis) distribution and habitat suitability in Nebraska. Thesis, University of Nebraska, Lincoln, USA.

Comments

A THESIS Presented to the Faculty of The Graduate College at the University of Nebraska In Partial Fulfillment of Requirements For the Degree of Master of Science, Major: Natural Resource Sciences, Under the Supervision of Professor Craig Allen. Lincoln, Nebraska: September, 2016

Copyright (c) 2016 Nathan R. Bieber

Abstract

River otters (Lontra Canadensis) were extirpated in Nebraska by the early 1900’s, but in 1986, the Nebraska Game and Parks Commission (NGPC) began reintroduction efforts. Following reintroductions, the otter was listed as a tier-1 at-risk species in Nebraska. With increasing otter populations, NGPC is evaluating a de-listing plan. In order to inform de-listing efforts, I surveyed Nebraska’s rivers documenting otter sign and used modeling techniques to estimate otter distribution and habitat suitability.

Otter sign surveys were conducted on the navigable rivers of Nebraska. Occupancy modeling techniques were used to examine patterns in otter detections. The best model incorporated distance to the nearest otter release site, beaver occupancy, and flow rate. The Niobrara, Elkhorn, and Platte rivers and the southern Loup River system were the areas most supported as areas likely to have otters.

Data collected by NGPC were used to examine patterns among historical otter records. Maximum entropy (maxent) modeling identified the Platte, northern Elkhorn, southern Loup River system, and sections of the Niobrara as areas most likely occupied. Maxent habitat suitability modeling identified the Platte, eastern Niobrara, southern Elkhorn, and southern Loup River system as areas with preferred otter habitat. The distance to a release site and flow rate had the strongest impact on model fit.

Results were consistent with estimates prepared by NGPC, and spatial correspondence between occupancy estimation methods was high. Future efforts to translocate or reintroduce more otters should focus on areas with high habitat suitability and areas with high occupancy estimates but few occurrence records.

Advisor: Craig Allen