Winter 2016-17 pushed high numbers of mule deer down into the path of traffic, stranded elk herds in unusual places and killed a good portion of the pronghorn that tried to wait it out in Jackson Hole.
But moose did just fine.
The largest species in the deer family, moose are well adapted to winter. Mangy moose are hard to come by this year, Wyoming Game and Fish Department wildlife biologist Aly Courtemanch said, and the reason might have been extended cold snaps in December and January that killed off ticks.
“Moose do much better in the cold temperature and much better in the deep snow than our other ungulates,” Courtemanch said. “They seemed to be doing pretty well this winter.”
Going by the raw count, Jackson Hole’s moose population is on the up. Counting from a helicopter in mid-February, Courtemanch came up with about 320 moose. She bumped up the estimate to 346 to factor in those that were detected during Nature Mapping Jackson Hole’s annual citizen-science “Moose Day” census, held Feb. 25.
In 2016, by comparison, Courtemanch tallied just 231 moose — the lowest assessment ever for when winter conditions have allowed complete aerial surveys. The 346 count is the most since 2010, a similarly severe winter.
“I think it’s a promising sign that perhaps the population is doing better,” Courtemanch said, “but it’s definitely not a huge improvement over previous years.”
Game and Fish’s goal for the Jackson Moose Herd is 800 animals.
This year’s higher number is likely linked to moose “sightability” being better during years with deep snow, Courtemanch said, which drives animals out of timber and down into open river bottoms and riparian areas.
This winter moose were largely absent from smaller, higher-elevation drainages and tended to be bunched up in the larger expanses of willows along valley floors. That dynamic was evident along the Gros Ventre River, where Courtemanch flew over one group of 40 moose at the Cottonwood Creek confluence.
“They were basically all together,” she said. “I’d never seen anything like that. Moose were popping up from the willows left and right. It was pretty amazing.”
One assessment of the health of the moose population — the ratios of calves to cows — looked up as well this year. The 47-to-100 ratio calculated was the highest Game and Fish has recorded since 1994, and there were even four cows spotted with twin calves, a relative rarity.
“I’m not sure exactly what’s driving that,” the biologist said. “It could be differences in predation or habitat changes that are making cows healthier.”
Calves fared pretty well across much of the moose range, she said. They also did well in areas populated with wolves, such as the Buffalo Fork and Gros Ventre drainages.
One location there were no calves — or any moose — was Grand Teton National Park’s Willow Flats area, a former moose winter range stronghold.
“Since I’ve been flying it for the last three years, we’ve never seen a moose in Willow Flats,” Courtemanch said. “It shows that a lot of the moose winter areas are basically empty now that the population is so low.”