Study predicts huge decline of Jackson Hole elk, especially if refuge keeps feeding

The National Elk Refuge will once again examine the future of its elk feeding program, revisiting a reliably fraught topic that’s sure to elicit strong calls to stay the course. 

A new study by the U.S. Geological Service, however, suggests that continued feeding would likely transform the Jackson Elk Herd into a population that bears little resemblance to the group that’s been intensively researched since the days of pioneering biologist Olaus Murie. 

The scientific investigation is intended to help U.S. Fish and Wildlife Service officials anticipate what lies ahead as they chart the Elk Refuge’s future. 

“Continued feeding is not the same thing as the status quo, because it does not maintain the current numbers of elk that we’ve seen in the past,” USGS disease ecologist Paul Cross told WyoFile. “People might be hoping for that, but [the status quo] is not something that our models suggest is likely.” 

The USGS’ modeling provides a preview of some of the likely options, or “alternatives,” outlined in the forthcoming environmental impact statement that will guide the revision of the refuge’s bison and elk management plan. That revision will replace the refuge’s 2007 management plan and subsequent “step-down plan.” Those regimens were mostly ineffective at reducing the number of elk on the 24,700-acre property to 5,000 animals. Fewer elk would theoretically allow federal managers to forgo feeding during the average winter.

In the new study, USGS, Fish and Wildlife Service and academic research scientists projected how the Jackson Elk Herd would fare 20 years into the future under five different management scenarios while lethal chronic wasting disease propagates through the feedground region. The modeling assumed starting points of 11,000 elk and 1% CWD prevalence — which are both higher than the on-the-ground conditions today.

• Continue feeding: Unchanged elk feeding on the National Elk Refuge would ratchet up the prevalence of chronic wasting disease to an average of 35% of the herd. Meanwhile, the Jackson Elk Herd would decline by more than half to 5,200 animals.
• No feeding: Ending the refuge’s feeding program abruptly would reduce the size of the Jackson Elk Herd sooner, but the herd size would only dwindle to 6,700 — a 39% decline. Rates of CWD in the herd would reach an estimated 24%. 
• Increase harvest, then stop feeding: This management option assesses five years of heavy hunting to drive down the refuge’s population to 5,000 before stopping feeding. The herd is projected to decline by 45% to 6,000 animals in this scenario. CWD prevalence in the herd would reach 27%. 
• Reduce feeding: This strategy would taper alfalfa rations over 5 years before halting feeding altogether. The USGS’ modeling predicted that the herd population would decline by 45% to 6,100 animals while CWD prevalence would top out at 26%. 
• 3% disease threshold: The last scenario analyzed in the USGS model calls for continued elk and bison feeding on the refuge until CWD prevalence reaches 3%, then stopping feeding. The model predicted a 37% population decline to 6,900 animals and a 23% CWD prevalence under this management option. 

Complexities and assumptions

The research scientists selected the potential management options after querying Fish and Wildlife Service officials about their goals, management directives and constraints. Other agencies and stakeholders, including the National Park Service, Wyoming Game and Fish Department and hunting outfitters, were also consulted. 

“Oftentimes there isn’t direct research available to inform the performance of the alternatives in an [environmental impact statement],” USGS research ecologist Jonathan Cook told WyoFile. “The role that USGS had was to think in advance of the drafting of the EIS: What are the results that would be most informative? We spent over a year developing the models and the analysis.” 

Recognizing that the refuge doesn’t operate in a vacuum, researchers attempted to factor in real-world conditions. It was assumed, for example, that Wyoming would continue feeding elk on state-run feedgrounds up the Gros Ventre River drainage and in the Fall Creek Elk Herd. That assumption helps explain why projected chronic wasting disease prevalence was so high, even when elk were no longer fed — and densely concentrated — on the National Elk Refuge. 

Whether Game and Fish does keep feeding elk on its feedgrounds long into the future remains to be seen. The state agency recently completed its first-ever feedground management plan. A targeted review of feeding operations for the Jackson Herd is also underway, though making wholesale changes will require broad buy-in from the public. Even the Wyoming governor would need to be on board in order to close a feedground. 

The USGS’ modeling also used 1% prevalence of CWD as a starting point, which is higher than current infection rates. A single elk, killed by a hunter in Grand Teton National Park over four years ago, has tested positive for the always deadly prion disease. Meanwhile, CWD was just discovered for the first time in the adjacent Fall Creek Elk Herd. 

Expert projections, combined with modeling, were used to estimate how quickly CWD prevalence will climb within the feedgrounds. There’s “a lot of uncertainty,” said Cross, the lead USGS researcher. But there are also the prospects of very high levels of the disease, he said, citing a Wyoming study that found 37 out of 39 captive elk died from CWD at the Tom Thorne/Beth Williams Wildlife Habitat Management Area and catastrophic consequences for some wild mule deer herds. 

“The Wind River population — it is mule deer — but it shows that CWD can go really quickly to high levels,” Cross said. “Zero to 70 [% prevalence] in 10 years.” 

Redistributed 

The USGS analysis also predicted how elk would redistribute across the landscape if the feeding system they’ve been drawn to for a century disappears. 

Exactly half of elk would stay on the refuge in the absence of feeding, the modeling predicted. A recent mild winter, 2017-’18, showed that virtually the entire Jackson Herd can dwell on the federal preserve under the right conditions. 

In the absence of feeding, about 14% of the refuge’s elk would move into the Fall Creek Herd — mostly moving to the state-run South Park, Horse Creek and Camp Creek feedgrounds. Another 19% of the elk, the research predicted, would spend the winter naturally foraging out on the landscape in the Jackson Herd region. The last big cohort — about 18% of the refuge’s elk — would leave to spend their winter eating hay on the elk feedgrounds up the Gros Ventre River drainage. 

Bison, which cannot contract chronic wasting disease, were also assessed in a separate chapter. The analysis found that continuing with feeding resulted in the highest number of bison, with herd sizes and hunting opportunities slightly lower under all the other scenarios. 

Another chapter of the USGS research takes stock of the social and economic consequences of the various management options. It spells out, for example, how hunting license revenue would vary. Hunters, the study predicted, would spend $76 million on tags over the next 20 years in the no-feeding scenario, but $101 million if the refuge selects the “increased harvest” option. Regardless of what managers choose, hunting opportunities are expected to eventually plummet relative to the status quo because of the effects of chronic wasting disease. 

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Fewer elk. Sicker elk. That’s what the experts expect if Wyoming keeps on feeding.

“Projections are for the harvest declining by up to 75%,” Cross said. “There’s a dramatic decline in harvest, in all scenarios, though the depth of it is a little hard to say.” 

The USGS’ data and analysis are intended to help wildlife managers understand the tradeoffs of the elk feeding equation in a new era with chronic wasting disease on the landscape. The findings, Cross said, suggest that the ecosystem is at “an inflection point.” 

“Regardless of the decision made, things will be different in the future than they have been in the past,” Cross said. “It’s a really important moment.” 

The U.S. Fish and Wildlife Service’s regional office did not grant the National Elk Refuge staff permission to give an interview for this story. 

The Wyoming Game and Fish Department has yet to formally review the U.S. Geological Survey’s final analysis, which published last week. In advance of that review, Brad Hovinga, the agency’s Jackson Region supervisor, has a number of questions. 

“Certainly, we have concerns with the amount of assumptions in this analysis,” Hovinga said. “There’s a lot we don’t know about the disease or what could happen.” 

The USGS’ entire 146-page analysis is available for review below.