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Wyoming Range mule deer herd population plummets to record lows

(Wyoming Game and Fish)

GILLETTE, Wyo. — The Wyoming Range mule deer population plummeted following the severe winter of 2022 and 2023, with wildlife managers recording the lowest numbers in decades, according to the Wyoming Game and Fish Department. 

Recent aerial surveys of the Wyoming Range produced a population estimate indicating the herd is comprised of around 11,000 animals, a considerable decline from the February 2023 estimate of 30,000 individuals, per Game and Fish. 

While surveys wouldn’t ordinarily be done two years in a row, wildlife managers ultimately decided they needed to obtain a full and accurate picture of the herd’s population following an unprecedented winter season last year, according to Doug Brimeyer, Deputy Chief of Wildlife. 

The survey reportedly indicated the fawn ratio for the deer herd was 34 fawns for every 100 does, the lowest on record since the herd was designated in 1982, per Game and Fish, which says low fawn ratios can be attributed to the intense energy demands of a harsh winter. 

“When doe deer are stressed due to severe winter conditions, they may experience decreased reproductive success that leads to lower conception rates and reduced survival rates of fawns born shortly after the winter,” Game and Fish South Jackson Biologist Gary Fralick said. “The lost fawns will result in a shift in the age structure of the population.”

Buck numbers were down as well, with the survey recording 24 bucks for every 100 does, also the lowest on record, Game and Fish says, adding that yearling buck numbers were down likely due to the high mortality of buck fawns that came during the winter months. 

Of the animals that survived the harsh winter last year, though, there was abundant forage and less competition, with a recent capture effort by the University of Wyoming indicating deer had the highest fat levels since 2013. 

Fralick said the high fat levels are a result of increased forage production, fewer deer on the landscape, and many does being liberated from rearing fawns. 

“This year the winter ranges have received below-average snow, allowing animals to easily access abundant forage,” Fralick said. 

Wildlife managers feel nature is the most important factor affecting recovery of the Wyoming Range mule deer herd and consecutive years of favorable weather patterns will be critical components for the deer herd’s recovery moving forward, per Game and Fish. 

Brimeyer said the most important thing that can be done to help wildlife survive and recover from tough winters is to protect and enhance their habitat and connectivity between seasonal ranges. 

“[Game and Fish] and partners are committed to the recovery of the Wyoming Range mule deer herd and support projects that reduce deer-vehicle collisions, control cheatgrass, manage predators, and facilitate movement across important habitats,” Brimeyer said.