Weather, disease, and bighorn lamb survival during 23 years in Canyonlands National Park
Douglas CL. 2001. Weather, disease, and bighorn lamb survival during 23 years in Canyonlands National Park. Wildlife Society Bulletin. 29(1):297-305
The Island-In-The-Sky desert bighorn herd is the largest in Canyonlands National Park, Utah, and is used to re-establish herds in former habitat throughout the state. Responding to a concern of low lamb numbers following four years of transplant removals in the early 1980s, the author studied weather effects on lamb:ewe ratios. Using population data for the herd, he developed models that predicted a substantial amount, though not all, of the variation in lamb:ewe ratios. Two major weather factors were maximum May temperatures the same year lambs were born, which may correlate with dry soil and decreased nutrient value of forbs, and precipitation from January through March two years before lambs were born, thought to relate to body condition of ewes. Disease and unusual weather events could contribute to the lamb:ewe ratios but were not factored into the model. Survey miscounts could also affect the apparent accuracy of the model. Future use of this model should help managers predict lamb:ewe ratios and plan transplant removals accordingly.
- Type
- Journal Article
- Authors
- Douglas, Charles
- Units
- CANY
- Keywords
- Animal Studies, Atmospheric Sciences, Bighorn Sheep (Ovis canadensis), Climatology, Disease, Inventory, lambs, Mammals, Management, Monitoring, morality, Physical Sciences, Reproductive Success, Resource Management, Soil Science, Survival Rate, Threatened-Endangered-Sensitive Animals, Weather