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For more information on species & ecosystem science:

Wildlife Science
360-902-2515
wildthing@dfw.wa.gov

Fish Science
360-902-2700
fishpgm@dfw.wa.gov

Habitat Science
360-902-2534
habitatprogram@dfw.wa.gov

 
 

Lead Scientist: Cliff Rice

Ecoregions: Northwest Coast, North Cascades, West Cascades, East Cascades, Okanogan

Ecological Systems: North Pacific Maritime Mesic Subalpine Parkland, North Pacific Montane Massive Bedrock Cliff and Talus, Northern Rocky Mountain Subalpine Woodland and Parkland, North Pacific Alpine and Subalpine Bedrock and Scree

   
 

Population model results for the Bumping Unit.

 
   
 

Selenium Update

Previously, we speculated that low levels of selenium may have contributed to mountain goat population declines.  However, selenium levels in blood serum from captured mountain goats did not support this idea.  Although selenium levels were low in a few individuals, generally they were above levels considered deficient for domestic animals.

   

Mountain Goat Ecology

Population Models

Project Description

In 1961, WDFW estimated the number of mountain goats in Washington as 10,355. Are there really only 1/3 as many mountain goats now as there were then? It is difficult to say as the 1961 estimates were quite subjective. Nevertheless, it is clear from accounts for particular areas that mountain goat numbers in some areas have declined substantially, or even drastically, over this period. In Olympic National Park, many mountain goats were removed intentionally due to their non-native status in the Olympics, but what about other areas? Many explanations have been proposed, including disease, predation, recreational disturbance, winter habitat modification, loss of alpine meadows, and excessive harvest, but there has been little solid information on which to evaluate these potential effects. An exception is the factor of sport harvest because we have good records of mountain goat harvest over this period. Although current harvest levels are very conservative, with about 20 permits issued by WDFW each year (for specific areas where mountain goat populations are doing well), past harvest was much higher. In the 1960s, 1970s and early 1980s, 200-400 mountain goats were killed by hunters every year. In those days, it was thought that mountain goats were biologically much like deer, and could be harvested fairly intensively. We now know that is not true, that mountain goats have low fecundity and late reproductive maturation, and harvest needs to be conservative.

We used computer population models to evaluate the effect of past harvest on populations. We modeled mountain populations in seven areas for which we had estimates from 1961, recent population estimates from surveys (and sometimes intermediate estimates), and a good record of harvest. As with all computer models, we had to make some assumptions, but generally our models showed that the magnitude of declines since 1961 were about what would be expected given the harvest that took place. While other factors may have played a role in a few locations or a minor role in general, it is highly plausible that mountain goat population declines in the last 50 years are the result of hunting regulations being too liberal. The good news is that this is a problem that is easy to fix and actually has been fixed, and if our models are correct, recovery can be expected. Nevertheless, this may take some time and for some areas, population augmentation through translocations may be called for.

Key Findings

  • Past declines are likely the result of excessive harvest.
  • Mountain goat populations are sensitive to harvest.
  • Harvesting predominately males has less impact.

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