New Study Reveals the Effects of Continued Feeding of Jackson Herd Elk

There’s nothing quite like beholding the elk at the storied National Elk Refuge in Jackson Hole, Wyoming. With over 5,000 elk migrating to the sacred grounds each year, it’s a great place to spot these majestic animals, despite a new study suggesting, it might not always be.

Headed up by the US Geological Service, the new study, which also included help from the US Fish and Wildlife Service, worked to project just how the Jackson Elk Herd will fare 20 years in the future by splicing in five separate, but possible, chronic wasting disease management scenarios.

With a starting point of 11,000 elk and a CWD prevalence of 1 percent (both of which are higher than current conditions), researchers outlined five possible scenarios and their projected outcomes. According to the study, the five scenarios are as outlined below:

1. Continue feeding - The NER will continue to provision supplemental food to bison and elk during winter months based on forage availability and number of conflicts. 

2. No feeding - The NER will immediately stop provisioning food to bison and elk during winter months. 

3. Increase harvest, then stop feeding (increase harvest) - The NER will continue to provision food to bison and elk during winter months for the next 5 years, then stop feeding. During those 5 years, the NER will work with the Wyoming Game and Fish Department (WGFD) to increase elk harvest and attempt to reduce the population of elk that overwinter at the NER to 5,000 animals. 

4. Reduce feeding, then stop feeding (reduce feeding) - The NER will provision a reduced ration to elk during winter months for the next 5 years to reduce the elk population size prior to feedground closures. Exclosures will be designed to protect aspen stands in the south region of the NER, and for willow and cottonwood north of the NER. 

5. Stop feeding after 3 percent CWD prevalence is measured in Jackson elk (disease threshold)  - The NER will continue to provision food to bison and elk during winter months until CWD sampling reveals 3 percent prevalence in the Jackson elk herd, at which point all feeding activities will cease at the NER

Using real-world conditions, predictions and modeling, researchers made estimations on how quickly CWD would increase within the feedgrounds. While there remains to be a fair bit of uncertainty, researchers are confident in the data used to explain their predictions. 

Under the continued feeding scenario, researchers found that unchanged elk feeding on the Refuge would result in an increase in the prevalence of CWD to an average of 35% of the herd and a decline in overall populations to about 2,500 animals.

The no feeding scenario too resulted in dramatic declines in elk numbers and in a shorter period of time. Under the second scenario elk numbers would drop by just 39 percent and CWD prevalence would clock in somewhere around an estimated 24 percent.

Increasing harvest and then stop feeding used five years of heavy hunting as a tool to drive down elk populations and found that herd reductions would be at about a 45 percent decline and that CWD prevalence would reach 27 percent.

Under the reduced feeding scenario, the feeding of rations would taper off over a five-year period before stopping the feeding all together. Under this model, researchers predicted that the herd population would decline by 45 percent and CWD prevalence would settle in somewhere around 26%.

And finally, under the disease threshold management scenario, the model called for continued feeding of both elk and bison until the CWD prevalence reaches a 3 percent threshold. At that time, the feeding would be halted. This final scenario predicted a reduction of 37 percent in elk herds paired with a 23 percent CWD prevalence.

While this (and many other) studies don’t profess to hold all of the answers, they do serve as an important building block for the future of wildlife management. Despite Wyoming Fish and Game not yet having formally reviewed their findings, the study is bound to help the agency further grasp the tradeoff of elk feeding as chronic wasting disease continues to develop on the landscape.  

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