Since 2009, Alaska Department of Fish and Game has funded innovative research to address recent declines in Dall’s sheep populations. Dall sheep are live-captured with nets fired from a helicopter. GPS and VHF collared sheep are tracked and sampled to evaluate potential limiting factors including; predation, weather events, nutrition, reproduction, and disease, and to assess habitat use Collared sheep in the population allows for accurate estimation of abundance, cause of death, foraging behavior and preferences, pregnancy and birth rates, and body condition.
During the next two years and in partnership with Alaska Pacific University, researchers will investigate how warmer and wetter winters and changing climate may be affecting sheep habitat. Research will focus on: 1) whether available sheep habitat has decreased over the last 50 years; and 2) measuring the nutritional content of seasonally important forage and how nutritional content may change between summers. The intent of this research is to provide insight as to how climate affects habitat quality and how the sheep utilize that habitat. Key findings will inform management and future assessments of this iconic and valuable resource. This research is funded by cost sharing: 75% Wildlife Restoration Program + 25% non-federal match = $218,184.
Unique to Chugach sheep, predators had much less impact than predicted and animals were found to be in consistently poor body condition. The low number of deaths attributed to predators, and the broad distribution of deaths across predator species, suggests strongly that predation is not exhibiting a population level effect on Chugach sheep populations. Similarly, the low presence and prevalence of major wildlife diseases indicate that disease does not play a major role in this population at this time. However, their poor body condition, coupled with chronically low pregnancy rates, suggest strongly that there is a habitat and/or a nutrition issue.
Dall’s sheep are one of the most recognized and highly valued wildlife species in Alaska. Dall’s sheep provide important sport and subsistence hunting and non-consumptive viewing opportunities; contributing to the economy of Alaska. The Chugach Mountains overlook Anchorage and sheep in these mountains are of great importance to the State’s largest population center.
The population of Dall’s sheep near Anchorage provide an ideal opportunity to investigate the effects of climate on a large mammalian species. Variable and low pregnancy rates, even in years with moderate winters, strongly suggest that summer habitat quality has become a key limiting factor for this population.