Interactions between feral horses and desert bighorn sheep at water

Stacey Ostermann-Kelm, Edward R. Atwill, Esther S. Rubin, Mark C. Jorgensen, Walter M. Boyce

Research output: Contribution to journalArticlepeer-review

30 Scopus citations


We studied sympatric populations of native bighorn sheep (Ovis canadensis) and feral horses (Equus caballus) to quantify their spatial and temporal overlap and to determine whether horses interfered with use of water by bighorn sheep. We observed no evidence of direct competition, but our field experiment, which involved placing desert-acclimated domestic horses near watering sites used by bighorn sheep, demonstrated that bighorn sheep avoided sites with horses nearby. The presence of domestic horses near a watering site preferred by bighorn sheep resulted in a 76% reduction in the number of groups of bighorn sheep coming to water at that location and a concomitant increase in the number of bighorn sheep watering at other sites. An experimental approach to studying competition between large mammals has been problematic and to our knowledge this study constitutes the 1st manipulative field experiment to test for competitive interactions between feral horses and native ungulates.

Original languageEnglish (US)
Pages (from-to)459-466
Number of pages8
JournalJournal of Mammalogy
Issue number2
StatePublished - Apr 2008


  • Bighorn sheep
  • Competition
  • Equus caballus
  • Feral horses
  • Ovis canadensis
  • Peninsular ranges
  • Resource partitioning
  • Wild horses

ASJC Scopus subject areas

  • Animal Science and Zoology


Dive into the research topics of 'Interactions between feral horses and desert bighorn sheep at water'. Together they form a unique fingerprint.

Cite this