Relative abundance of the Prairie Long-tailed Weasel (Mustela frenata longicauda) in southwestern Alberta


  • Garry E. Hornbeck Wildlife & Company Ltd., 312 Cedarille Crescent, SW, Calgary, Alberta T2W 2H7
  • Dan Soprovich Bluestem Wildlife, 10 Parkdale Drive, Swan River, Manitoba R0L 1Z0



Mustela frenata longicauda, Prairie Long-tailed Weasel, capture rate, capture probability, relative abundance, Peromyscus maniculatus, Deer Mouse, Sorex, shrew, Microtus, vole, Alberta


Prairie Long-tailed Weasels (Mustela frenata longicauda) were live-trapped during fall 2005, 2006, and 2007 at Pine Coulee Reservoir and during fall 2005, 2008, and 2010 at Twin Valley Reservoir in southwestern Alberta. Our objective was to estimate the relative abundance of the Long-tailed Weasel and to estimate the relative abundance of small mammal prey. Body size and capture rates are reported for Long-tailed Weasels, and we report capture rates of small mammals. Annual capture rates for Long-tailed Weasels at Pine Coulee Reservoir were 0.44, 0.41, and 0.50 individuals per 100 corrected trap-nights (0.42, 0.38, and 0.48 individuals/100 trap-nights) in 2005, 2006, and 2007, respectively. No Long-tailed Weasels were captured at Twin Valley Reservoir. The probability of capturing zero Long-tailed Weasels at Twin Valley Reservoir was very low, assuming a true capture probability equivalent to that observed at Pine Coulee Reservoir. Deer Mice (Peromyscus maniculatus) were the most abundant small mammals captured in both project areas. Few shrews (Sorex spp.) and voles (Microtus spp.) were captured in either area.