Pronghorn population, hunting tags down due to habitat, climate woes
Fewer archers and shooters will pursue pronghorn in the forthcoming hunting season after snowstorms and drought prompted Wyoming Game and Fish Department to significantly reduce the number of licenses it issued this year.
Game and Fish estimated there to be 388,500 “speed goats” after the 2020 hunting season, the last estimate for which data is available. That’s 40,700 shy of the objective of 429,200 — about 9 percent below the population goal in the pronghorn’s stronghold state.
The agency expects 42,646 hunters this year, a drop of 9 percent from 2020. The agency expects them to have an 86-percent success rate and spend an average of 3.9 days hunting per animal killed.
Because of expected fluctuations in such large wildlife herds, the agency considers a population to be at objective if it is within 20 percent, plus or minus, of the specific figure. A dip in numbers is not always worrying because pronghorn are resilient, with does usually birthing twins, said Doug Brimeyer, wildlife management coordinator for Game and Fish.
“When we see a wildlife population reproduce at between 15-to-20 percent per year, that’s pretty astounding,” he said. “That’s why I’m a little bit optimistic.
“They just have a potential to bounce back.” Brimeyer said. “Unfortunately, we’re not seeing that across the state,” he said, because drought and spring storms combined to create difficult conditions for some herds.
Wildlife viewers and hunters monitor the species and its fate with the acuity of pronghorn themselves. The Game and Fish Department’s logo proudly portrays a pronghorn antelope.
“Wyoming is kind of the pronghorn state [with] more [pronghorn] than most other states combined,” Brimeyer said. “That’s our iconic species.”
Biologists review the population objective for herds every five years, but have not changed the statewide number for some time. But the objective is dependent principally on habitat, for which changing climate could create a long-term challenge.
“It all adds up to what the land can sustain,” Brimeyer said.
Game and Fish biologists keep tabs on pronghorn throughout the year, conducting line-transect aerial-abundance surveys in May and early June, Brimeyer said. In August, they tabulate sex and age ratios in classification surveys, keeping track of over-winter survival of yearlings, among other things.
Habitat biologists pick through sagebrush and forbs to characterize the amount of food available before winter sets in.
In 2020, one Game and Fish biologist saw trouble ahead in the Lander region. “[S]taff observed a 40-percent decline [in 2020] in the number of pronghorn along the same routes driven in 2019,” Stan Harter wrote in a newsletter. “A bigger concern is that the ratio of fawns per 100 does was the lowest observed in 25 years.”
He observed only 0.6 inches of rain between Easter and Labor Day, plus a “pretty hard” 2019-’20 winter. The combination produced a “pretty rough year,” for pronghorn.
The number of yearling bucks was down, indicating poor over-winter survival, Harter wrote.
“Several groups of pronghorn were observed in September with ribs and hip bones showing, indicating these animals were having a hard time finding good forage last  summer,” his newsletter read. “All this information points to a declining population.”
Harter’s observations were localized. But nature was throwing combination punches in other parts of the state too, including farther southeast.
Justin Binfet, the agency’s Casper wildlife management coordinator, witnessed a cataclysm in the 2020-21 winter.
He wrote Brimeyer an email earlier this year titled “antelope license cuts — disaster declaration.” Hunt areas 30 and 31 southeast of Casper — where part of the Medicine Bow Herd lives — “received extremely deep snow that would then freeze very solid each night, rendering access to forage impossible,” his note read.
Because the winter had been mild, antelope were at higher elevations. The storm forced them to migrate through crusted snow and cold that “made movements extremely difficult.”
Field workers saw many dead antelope and survivors congregating on plowed county roads.
“We … observed several instances of large groups of antelope getting hit by vehicles … as they had nowhere else to go,” Binfet wrote. He recommended 450 fewer 2021 hunting licenses be issued than he had planned.
Spring didn’t bring much relief in places, Brimeyer said.
South of Pinedale “some of the grass species didn’t even come out of dormancy from the winter period,” he said. “Overall the forage production has been pretty poor when you get south of Rock Springs.”
South and east of Sheridan Game and Fish reduced pronghorn licenses by 1,700 this season, Brimeyer said. In the Casper area, the quota was cut by about 3,000.
Around Lander, Daryl Lutz, region wildlife coordinator, explained reductions in a newsletter.
“Most of the cuts in license quotas are doe/fawn licenses,” he wrote. Buck/doe ratios were good enough to maintain the always-limited number of “any” antelope licenses, he wrote.
A few weeks of rain can make a difference, Brimeyer suggested. Between Casper and Laramie, “We’re now seeing moisture, [and] pronghorn are doing well.”
Periodic rains around Rock Springs in the last two weeks “kind of changed things,” he said.
Game and Fish evaluates herds’ population objectives every five years. If the agency finds environmental conditions have reduced the habitat’s carrying capacity, a new objective will be considered through the public process.
“The objective is tied to ideal habitat conditions,” Brimeyer said. “We’ll adapt to that if we see prolonged drought.”
Not everybody who shoots a .270 or .243 caliber bullet — two of the most popular pronghorn rounds — qualifies as an antelope biologist, despite keen interest. When numbers are down, wildlife managers can’t just make changes on paper and see results in the field.
“It’s not as easy as just not harvesting,” Brimeyer said. You have to adapt and see if there’s habitat there. It’s not as simple as raising objectives.”
Doe-fawn licenses — an indication of abundance — are available when the population is up and range, modified by drought and weather, has the capacity to nourish them.
“There are only so many mouths that can be sustained,” Brimeyer said, “otherwise, there’s winter mortality.”
As Wyoming regularly addresses its habitat and herd sizes, could climate change be a cause for hosting fewer antelope? “The reality of that is ‘yes,’” Brimeyer said.
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