6/2014 - Pilot–biologist Nate Olson assisted Alaska Department of Fish and Game in locating radio-collared cow moose as part of a long term study monitoring moose nutritional condition and subsequent productivity on the Western Kenai Peninsula. Moose were located daily starting mid-May through mid-June to identify when they calved and how many calves were born. We will continue to radio-track these moose through the year to record calf survival
This information is used to monitor the nutritional condition of a moose population and their subsequent productivity. Boertje et al. 2007 (Ranking Alaska moose nutrition: signals to begin liberal antlerless harvests, Journal of Wildlife Management 71:1494-1506) outlined several measures that include body condition (i.e., rump fat or total body fat), parturition rate, twinning rate, short-yearling weight, and browse removal. Since there are sometimes conflicting results of individual measures and lots of inter-annual variation, it is prudent to look at multiple measures across several years to successfully assess the overall nutritional condition of a population. Here’s a summary of just some of our measures.
1. Parturition rate (how many cows have a calf). Adult cow moose (≥3 years of age) in areas with little or no nutritional constraints typically have a parturition rate near 90% or higher. Boertje et al. (2007) documented a nutritionally stressed population south of Fairbanks as having the lowest mean parturition rate (70%) on record in Alaska. The mean parturition rate of cows in GMU 15A over the past 3 years is about 70%. The parturition rate in GMU 15C over the past 3 years is >75%.
2. Twinning rate. Twinning can be variable across a moose range and is a reflection of the quality of summer range, and to a smaller degree, the condition of adult cows coming into a summer. In a long-term monitored population south of Fairbanks, twinning has ranged from a high of 49% to a low <10%. In GMU 15A, the twinning rate was 72% for two years in the early 1980s and has declined to just over 25% for the past 4 years. Twinning in GMU 15C is higher and has averaged over 35% over the past 4 years.
3. Calf Survival. Annual calf survival in 2012 was relatively low. Less than 15% of the calves in both 15A and 15C survived a year. The record deep snow fall during the winter of 2011/12 likely influenced the maternal condition, and therefore, the health of the newborn calves in the spring of 2012. The following year, calf survival was much higher in GMU 15C but still very low in GMU 15A.