Shiras moose | Leslie Patten Books: Wild Places, Sacred Spaces

What’s happening with the Moose in NW Wyoming

Posted on April 23, 2010 by Leslie

Moose track

Although I’d been hearing from local hands about moose visiting their properties all winter, I’d seen no sign. But just the other day, on a walk through the springs area of the nearby forest, 2 yearlings watched my neighbor and I casually as we approached on the trail. I held the dog, who didn’t even notice them, and we all had a few moments of moose/human communion. Ah, what bliss!

The yearlings went up the hill, we continued along the springs, when I looked down below into the newly logged private lands to catch a glimpse of Mama Moose, big and beautiful, running through the woods.

Yearling moose tracks next to Koda's track

I’d downloaded Scott Becker’s Master Thesis last fall and finally got around to reading it. He did a study on the moose around the Jackson area, including Dubois, south Yellowstone, and the Tetons. Here are some of the highlights from his study:

1. Few, if any, moose existed in Wyoming prior to 1850. Sporadic observations of moose occurred in NW Wyoming after 1850, but its believed the population didn’t begin to increase and expand until after the establishment of Yellowstone National Park.

2. Moose suffer heat stress in winter when temperatures are above -5 degrees celsius (23F); 14 degrees celsius in summer provokes heat stress (57F) and above 27C for extended periods of time is unsuitable for moose without refugia (80F)

3. Migrations between seasonal ranges follow traditional routes and that knowledge is passed from parent to offspring. Thus it may takes several generations for moose to adapt to habitat alterations that impact seasonal movements and ranges.

4. Some of the most important elements of habitat quality include coniferous forests, especially during spring when increasing ambient temperatures limit foraging activities of moose during the day. Moose movement is very concentrated in winter and dependent on coniferous forests. Moose population density and calf-cow ratios for the north Jackson herd began to decline shortly after the ’88 Yellowstone fires.

5. The north Jackson herd is in a steady decline. When female moose are healthy, they usually have twins. The results of Becker’s study indicate that nutritional quality, rather than the availability of habitat may be the most important determinant limiting population growth.

6. The impact of predators on calf survival appeared to be minimal. Although wolves did account for some adult female mortalities, the effect of wolf predation on this population appeared to be minimal. The apparent preference for elk by wolves in the GYE was likely due to the greater abundance of elk in the area. Also, because elk are in herds, its easier for wolves to follow and find them. While moose are solitary and the occasional predation is usually due to happenstance.

7. Management implications: Mature coniferous forests are an important component of Shiras moose habitat selection in winter and summer. Thus disturbances that reduce the amount of mature forests could negatively affect moose population performance.

8. Becker concludes that nutritional quality of habitat is the most important factor in the declining moose population in the northern Jackson herd. Habitat quality has been affected by large wildfires, insect outbreaks, widespread drought since the 1990’s, and global warming. Predators are playing a minor role in the decline of moose in northern Wyoming.

Here’s a video taken last fall of a male and female in the willows just down the road. You can turn the ridiculous narration off if you want.