Southwest ND Deer Surviving EHD, Habitat Loss

Despite last year showcasing one of the worst outbreaks of epizootic hemorrhagic disease (EHD) – a midge-borne illness that impacts primarily whitetailed deer, but did infect and kill mule deer, a few pronghorn and even an elk in southwestern North Dakota late last summer and fall – the region's deer herds remain relatively stable headed into the fall hunting seasons according to North Dakota Game & Fish Department (NDG&F) Big Game Supervisor Bruce Stillings.

"The populations are generally looking good, we've been seeing a slow increase in the population since 2013," Stillings comments on the southwests mule and whitetailed deer, adding that the disease impact was minimal, particularly outside of unit 3D1, "we were really expecting a pretty major hit on our whitetails in the southwest units and we thought that would certainly show up in our hunter success rates from the fall hunting season, and for the most part, that just wasn't the case."

The hunter success from the period following the outbreak, along with this spring's new crop of fawns has Stillings and other agents of the NDG&F optimistic for this fall's hunting opportunities, considering how widespread the reports of dead big game were in that quadrant of the state. EHD was so bad that biologists confirmed not only the significant and wide-spread affliction of whitetailed deer throughout the southwest, but also infections and deaths in pronghorn, mule deer and even an elk which was killed by the disease that manifests when water sources become concentrated and wildlife congregate near what remains in late summer and are exposed to the midges which bite and transfer the illness. So, while EHD was prevalent and long-lived last season, it's likely the whitetail populations were plentiful enough to survive without much of a setback.

"Last year we had one of the most severe outbreaks of EHD on record, and certainly the most extreme case since I've been on board in the last 20 years. We had over 100 reports of dead deer, which can range anywhere from a single dead deer to maybe over 20 dead deer. It was also a much longer than a normal EHD season, with that real mild and warm fall and late summer. Our actual last confirmed EHD case occurred on November 2, believe it or not," Stillings recalls.

Mule deer populations remain stable to slightly increasing and are still doing well in southwest North Dakota. This spring's fawning season was successful for the most part, based on anecdotal reports and secondary observations on recent fly-overs for pronghorn, and a good crop of young muleys has been reported this spring and early summer. Stillings is cautiously optimistic that the young deer will survive the summer drought, and the agency will get a better understanding of fawn recruitment as they learn more in October and November when hunter reports and other survey results come in. The biggest concern on the landscape, however, remains the loss of habitat which continues throughout the southwestern portion of the state. With the drought impacting the quality of what remains of the rangeland that sustains both species of deer, there is an air of concern.

"We've lost a tremendous amount of high-quality deer habitat in the form of CRP; it can vary from losses anywhere from 35 to 70 percent of our CRP that we've lost in particular hunting units," Stillings cautions, "that CRP provided valuable wildlife habitat in general, especially high-quality fawning habitat and also year-round habitat," he concludes.

Chronic wasting disease (CWD) continues to be present on the southwestern landscape in relatively low amounts as containment methods such as transport prohibitions and baiting restrictions look to stem the tide of the illness which affects both mule deer and whitetails. Five whitetailed deer in unit 3F2 were documented with CWD in 2020 samples for a prevalence rate of around two percent, while nine mule deer tested positive in the unit for a prevalence rate of five percent. One mule deer in unit 4B tested positive for the disease from all samples taken for a prevalence rate of under one percent. The disease can be spread through deer saliva between individual animals, and as a result, the use of bait during hunting activities remains prohibited in southwestern deer units 4A, 4B, 4C, 3E1, 3E2, 3F1, 3F2 and that portion of 3C west of the Missouri River. Additionally, those portions of deer carcasses that often harbor the disease including the head, brain and spinal column cannot be transported out of those units where the disease has been detected: 3F2, 4B and 4C.