Dryland river restoration via carnivore reintroduction: Nonnative fauna dominate diets of river otters reintroduced to the Upper Rio Grande

Gabriela A. Wolf-Gonzalez, Sean M. Murphy, Matthew T. Springer, John J. Cox

Research output: Contribution to journalArticlepeer-review


Dryland rivers often harbor abundant populations of nonnative species that threaten native fauna and negatively alter ecosystem structure and function. Native semiaquatic carnivores, such as river otters (Lontra canadensis), that could predate nonnative fauna have been extirpated from many dryland rivers. During 2008–2010, river otters were reintroduced to the Upper Rio Grande (URG), a principal dryland river in the arid southwestern USA that has been colonized by dozens of nonnative fish and invertebrates. We conducted a scat-based food habits study and investigated whether otter reintroduction could be useful for managing nonnative aquatic fauna via predation. Across seasons, nonnative crayfish and fish were the dominant prey items in otter scats; crayfish frequency of occurrence was highest (61–95%), followed by nonnative suckers (7–26%) and trout (3–28%). After accounting for heterogeneous sampling effort between seasons, multi-level models estimated 0.77–0.93 probabilities that scats contained crayfish, compared to 0.05–0.21 and 0.03–0.14 probabilities for suckers and trout, respectively. Reintroducing river otters, and possibly other semiaquatic carnivores, to degraded dryland rivers might be an effective conservation action for controlling nonnative faunal populations within the biomic approach to river restoration, which could reestablish trophic cascades that improve ecosystem structure and function.

Original languageEnglish
Article number104793
JournalJournal of Arid Environments
StatePublished - Sep 2022

Bibliographical note

Funding Information:
This research was funded by New Mexico Department of Game and Fish (grant # 171012 ), which contributed to the study design but had no role in the collection, analysis, or interpretation of data, writing of this article, or the decision to submit this article for publication. Supplemental funds were provided by the Department of Forestry and Natural Resources and the Student Sustainability Council at the University of Kentucky .

Funding Information:
The authors declare the following financial interests/personal relationships which may be considered as potential competing interests: .John J. Cox reports financial support was provided by New Mexico Department of Game and Fish . Sean M. Murphy reports a relationship with New Mexico Department of Game and Fish that includes: employment. Author S.M. Murphy was an employee of the primary funding entity, New Mexico Department of Game and Fish, during the first two months of data collection. All other authors declare no conflicts

Publisher Copyright:
© 2022 Elsevier Ltd


  • exotic Species
  • Food habits
  • New Mexico
  • Restoration ecology
  • River otter
  • Southwest

ASJC Scopus subject areas

  • Ecology, Evolution, Behavior and Systematics
  • Ecology
  • Earth-Surface Processes


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