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Moose cow and calf
Denali •
Wrangell-St. Elias •
Yukon-Charley Rivers
Moose Monitoring Status and Trends: Yukon-Charley Rivers
Yukon-Charley Rivers National Preserve’s 6th and most recent moose survey was conducted in the
fall of 2006. Park scientists flew over 841 square miles, or 151 survey units, and counted the
number of moose seen on the ground. After a statistical analysis of the results, the verdict
is in: though low in numbers, the population of moose in Yukon-Charley Rivers is stable.
Every three years, biologists monitor moose populations in Yukon-Charley Rivers National
Preserve. Surveys are conducted by air over a 3000 square mile area in the Yukon River Valley
between Eagle and Circle. All of the land in the study area is divided into 555 units that
equal about 5.5 square miles each. Since the area is so vast, biologists survey a randomly
selected group of units that equal about a quarter of the total study area. From this sampling
of units, biologists are able to extrapolate with a high degree of certainty (90% reliability)
population estimates for the entire 3000 square mile survey site.
The total number of moose in Yukon-Charley Rivers for the fall of 2006 was 726, give or take
about 140. This is roughly equal to about 1 moose for every 4 square miles of the preserve.
Of the population, 37% were bulls, 48% were cows, and 15% were calves. When these numbers are
compared to past survey results, it is evident that there is a low density but stable population
of moose in Yukon-Charley Rivers National Preserve. Moose harvest numbers were stable as well.
29 moose were harvested within Yukon-Charley’s boundaries in the fall of 2006. Over the
past 20 years, bulls hunted in the preserve have averaged 26 per year. Because we know from
monitoring that the bull to cow ratio is good and increasing slightly, it’s unlikely that
human harvest is having any detrimental affects on the population. Some Alaskan’s believe
this area can support many more moose than currently exist. Moose populations
in this region are affected by predation from wolves and bears. Predator control throughout
Alaska is controversial and has not been proven to increase moose and caribou numbers in most
cases. If predator control surrounding Yukon-Charley Rivers does influence
an increase in the number of moose, long-term success of the larger population is not known.
No thorough studies have been conducted to measure the quantity and quality of food available
for moose in Yukon-Charley Rivers National Preserve.
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Monitoring Importance:
Moose (Alces alces), are of special interest to each of the parks in the Central Alaska Network.
They are considered good indicators of long-term habitat change within park ecosystems because they
require a large quantity of resources from their habitat year-round. As a result, populations have
the potential to respond dramatically to changes in resource conditions. Moose are crucial to many
subsistence communities as a primary source of food throughout most NPS parks in Alaska, in addition
to being harvested by the general public on NPS preserve lands.
The Central Alaska Network has identified fauna (animal) distribution and abundance as one of its top
3 areas of interest. In general, the network wants to know where fauna are located across the landscape
and to monitor change in their distribution and abundance. Moose will be monitored in each CAKN park every
3 years. In addition to answering monitoring questions, the data will provide insight into other research
issues such as how change in plant communities or predator populations influences moose distribution and
abundance.
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Monitoring Objectives:
1. Determine changes in abundance, distribution, and composition of moose in each park every 3 years.
2. Estimate calf survival and recruitment success for moose in each park every 3 years.
3. Estimate annual human harvest of moose in CAKN.
 Bull moose
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