Hunters seek solutions as G&F continues to grapple with CWD

A meeting hosted by the Wyoming Game and Fish Department last month underscored the challenges of managing the area’s mule deer herds as hunters voiced concerns about the lack of quality bucks and hunting pressure at a time when wildlife officials are trying to slow the spread of the fatal chronic wasting disease.

Approximately two dozen hunters crowded into Greybull Town Hall on Dec. 12 for the discussion.  Sam Stephens and Rob Hipp, the wildlife biologist and game warden, respectively, in south Big Horn County, represented the G&F. 

Stephens outlined the challenges, initially focusing on the North Bighorn and Paintrock herds before transitioning to the nonmigratory populations along the river bottoms in the Big Horn Basin which have been decimated in recent years by CWD.

As part of a statewide study, the G&F has been tracking collared mule deer in five focal herds: the North Bighorn, the Wyoming Range, the Upper Shoshone, the Sweetwater and Laramie Mountains.  Other studies are ongoing as well which shed additional light on the crisis. 

The G&F started weighing collared fawns last winter. Of the five focal herds, the North Bighorn had the lightest fawns. They averaged 70 pounds compared to 75 for the Wyoming Range and Sweetwater, 78 for the Upper Shoshone and 79 for the Laramie Mountains.

“When you break it out by fawns we had collared in the North Bighorn, east slope fawns outside of Dayton and Sheridan were heavier than the ones on the west side.  Those in areas 50 to 53 were the lightest, on average about 66 pounds.”

Stephens detailed the 2024 annual survival rates of does and juveniles in the two primary herds, which were similar to the previous year. In the North Bighorn, doe survival was 83%, juvenile 71%.  In the Paintrock, doe survival was 83%, juvenile 70%.

Both herds are below G&F objectives.  In 2023, the G&F lowered its objective for the Paintrock herd from 11,000 to 8,000.  “We’re currently at the bottom end (of that objective range, with approximately 7,000 deer),” said Stephens.  The objective for the North Bighorn herd, which is spread out over a far larger area, hasn’t changed. Stephens said it remains at 20,000, adding, “We were at about 13,000 at the last estimate.”

Several hunters in attendance that night voiced concerns about the declining herds, saying they’ve been frustrated by the lack of mule deer, and especially trophy-quality bucks.

“I’d like to see one more big buck in my lifetime,” said Cliff Fink, a Greybull hunter. Like others that night, Fink said the G&F ought to consider changing its management approach because what it’s doing now isn’t working.  Some suggestions from the group included reducing the number of licenses available, modifying season lengths and establishing antler point restrictions.

Stephens said he isn’t convinced that switching to limited quota would impact the trophy potential of bucks in the population.  

As to the point restrictions, Stephens said he’d be concerned about an overinflation in the younger cohort. “It ties in with the limited quota discussion,” he said. “Are we at a place where we are willing to give up the management of bucks when we know the CWD prevalence is increasing in some of those cohorts, especially in places where CWD rates are static.

“I’m fearful that if we let off the gas at all, (the CWD rate) might jump like it has in (some other Bighorn Basin herds). They can be useful in trophy game management, but my issue is, what’s the ramification of trying something like that in light of CWD.” 

Stephens said the G&F is experimenting with different CWD management approaches in the Paintrock herd.  “I can tell you that from the standardized data we collect for all these herds, the Paintrock herd appears to be improving,” he said. “When you look at fawn recruitment and yearling buck recruitment ... both are increasing.  In the North Bighorn, that doesn’t seem to be the case.” 

Bighorn Basin herds

Stephens wasn’t as optimistic about the health of the non-migratory mule deer herds in the Big Horn Basin.  Because of their smaller home ranges, the CWD prevalence is much higher among those deer, particularly along the Lower Greybull and Shoshone rivers.

“When Bill was around,” Stephens said, referring to Bill Robertson, the longtime Greybull area game warden who was in attendance, “they were (counting) over 1,000 deer (between Hunt Areas 124 and 165).

“Now (when we do our classification surveys), we have to work our tails off for six nights to come up with 200 deer in the same area. It’s crazy.”

CWD prevalence really increased in 2019 and keeps climbing in those herds, he said.

Bottom line

When contacted after the meeting, Stephens reiterated that the main points he was trying to emphasize were that the mule deer herds in the Bighorn Basin are experiencing significant decline and that the decline is most pronounced in river-bottom dwelling non-migratory herds.

“We suspect this is due to significant increases in CWD,” he said.

“The Greybull River and Shoshone River Herds are currently sitting at approximately 50% prevalence (amongst adult male mule deer).  Given a two-year incubation period for a disease with a 100% fatality rate, that means that the annual adult mortality rate is equivalent to half the prevalence (in this case it means losing 25% of your adult males every year).  

“The migratory herds (North Bighorn and Paintrock) seem to be less susceptible to the disease and we suspect this is due to those deer utilizing a larger home range, where they are less likely to come into the CWD infected prions through direct (deer to deer) or indirect (environmental) transmission.  

“The Paintrock Herd is currently sitting at 17% prevalence which is relatively unchanged since CWD management strategies were implemented in 2022 when prevalence measured 18% (2019-21 average).”