Year of Publication

2020

Degree Name

Master of Science in Forest and Natural Resource Sciences (MSFNRS)

Document Type

Master's Thesis

College

Agriculture, Food and Environment

Department

Forestry and Natural Resources

First Advisor

Dr. John J. Cox

Second Advisor

Dr. Matthew T. Springer

Abstract

North American river otters (Lontra canadensis), native to every U.S. state and Canada, experienced extensive population decreases and range reduction until the mid-20th century as a result of overexploitation and habitat loss during European colonization. The last known river otter in New Mexico was killed on the Gila River in 1953, although unverified reports continued thru 2008. After a nearly 60-year absence from New Mexico, 33 adult river otters were reintroduced to the Rio Pueblo de Taos in the northern part of the state between 2008-2010; however, they were not subsequently monitored or studied. I characterized diet of this reintroduced otter population by collecting 877 scat samples from 20 latrine sites located on major rivers (Rio Grande = 16, Red River = 2, Rio Pueblo = 2) in Taos County, New Mexico between February, and December 2018. Hard prey remains were identified to family for fish and order for crayfish. Crayfish (66.2%) and fish (61.8%) were the most frequently occurring prey items in this study. Other prey items included mollusks and clams, birds, reptiles, and mammals. Salmonidae (39.6%) and Catostomidae (37.1%) were the most frequently identified fish families in otter scats, followed by Esocidae (14.3%), Cyprinidae (12.4%), and Centrarchidae (3.2%). Significant seasonal differences in occurrence of scat prey items was found for fish as a main prey group (p < 0.001), including the families Salmonidae (p < 0.001), Catostomidae (p < 0.001), Esocidae (p < 0.01), and Cyprinidae (p < 0.001), and for crayfish (p < 0.001). In summary, otters in the Upper Rio Grande appear to similarly consume prey to that found in other studies conducted in the U.S. My study provides the first dietary description of river otters in New Mexico and should inform otter management in the state.

Digital Object Identifier (DOI)

https://doi.org/10.13023/etd.2020.107

Funding Information

New Mexico Department of Game and Fish, 2018

University of Kentucky, College of Agriculture, Food, and Environment, 2017, 2018, 2019

University of Kentucky, Student Sustainability Council, 2018 & 2019

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