As EHD threat ends in west, CWD rises in east

North Dakota's deer hunters breathed a collective sigh of relief last week, much of which could be seen in the air outdoors as temperatures dropped down into the lower teens and even the single digits in some areas.

The first hard frost of the fall coming with those temperatures signaled the end to a long, difficult stretch for the state's population of white-tailed deer, especially in the western half of North Dakota, which this summer had been severely impacted by epizootic hemorrhagic disease, or EHD, a midgeborne virus that is frequently fatal to cervids, especially whitetails. North Dakota Game & Fish Department (NDGF) Wildlife Veterinarian Charlie Bahnson explained that the impact this year far exceeded that of the 2020 EHD outbreak.

"It was a bad year. We certainly had some units pretty substantially affected. Compared to previous years, we had a much larger geographic footprint than what we traditionally see in a bad year." Bahnson relates, adding, "we know that bad years are pretty strongly linked to drought, so of course most of the state had some level of drought."

The NDGF offered a tag turn-in option ahead of the firearms deer season opener for hunters in units along and west of the Missouri River, available to more than 30,000 people. That was up from the handful of affected units last year which were involved in the process, when only 4,500 hunters had the option. In tallies just prior to the Nov. 5 opening date, Bahnson said approximately 3,500 licenses had been returned to the department for a refund and restoration of preference points in next year's deer lottery. The NDGF had developed a heat map and a wildlife mortality form to track the advance of EHD on the landscape throughout the fall as hunters took to the field for grouse, pheasants and other small game ahead of the deer season, and several units – particularly those along the Missouri River – had dozens, if not hundreds of reports of whitetails which had likely succumbed to EHD in late summer and early fall, with most coming from areas outside of those units affected in 2020.

"You can think about it as a continuation of the outbreak from last year. We know when the disease comes into an area, not all deer are killed by it and those that survive develop a pretty strong immunity. So those southwest units, by and large those populations are a little more resilient to a viral threat like this, whereas on those adjacent units we're looking at deer that have never seen it before and they responded accordingly, [with] very high levels of mortality and some dramatic reports out there." Bahnson explains, adding that the number of reports has tapered, "typically what ends the outbreak is a hard frost, or a couple nights of hard frost, which kill that midge or at least slow down the life cycle substantially," he concludes.

But now, as one outbreak ends in the west, new concerns for a different one emerge in eastern North Dakota, as a case of chronic wasting disease, or CWD, a prion-based long-term neurological affliction for deer which is always fatal, was detected just across the Red River near Climax, Minn. The finding came from a 2.5-year-old buck harvested by a bow hunter in Minnesota and sampled by the state's Department of Natural Resources confirmed just days before the start of the North Dakota firearms deer season opener. The finding triggered an immediate response by the NDGF, setting up head collection sites, public outreach, and heightened surveillance efforts by the agency in firearms unit 2B which runs from just south of Fargo to Grand Forks on its eastern border, mere miles from the sampled deer's harvest site. The hope is to collect the heads of 300 deer from the gun unit to determine if the disease has made the jump across the Red River.

"We know that there's a positive deer there, what it means exactly is kind of undetermined at this point. Fortunately, the timing worked out to where we can really take advantage of the gun season, last minute here, to try to get a bunch more samples from that area to just put the finding in context." Bahnson relates, adding that collection sites have been established in Grand Forks, Fargo and Hillsboro, with an NDGF agent on the ground at the Hillsboro Cenex to discuss the issue with hunters.

CWD has been previously detected in Minnesota deer unit 604 north of Brainerd, unit 605 east of Minneapolis, and a cluster of units in the southeastern corner of the state near Rochester. In North Dakota, the disease has been limited to the northwestern and southwestern reaches of the state, resulting in transport and baiting restrictions in those units and surrounding ones to help limit its spread elsewhere in the Peace Garden State. This occurrence along the Red River is concerning to the NDGF and should be to sportsmen, as the herd in that region is considered contiguous, despite the border flow, which this year allowed easier travel between its banks by wildlife due to drought-lowered waters.

"We're responding accordingly. A deer that close can be assumed to be part of the same herd, it's a pretty continuous herd on either side of that river. We do know that interstates act as a pretty strong barrier, so that's maybe one good thing that I-29 does kind of limit travel, but I would really assume that Minnesota and North Dakota share the population that's along the river," Bahnson reveals.

Sites for deer head collection in unit 2B are established at the NDSU Veterinary Diagnostic Lab, 4035 19th Ave. N., Fargo; Tractor Supply Co., 4460 32nd Ave S., Grand Forks, and the Cenex at 105 Sixth St. SW, Hillsboro. Information on the newly established CWD surveillance process in unit 2B can be found at gf.nd.gov/wildlife/diseases/cwd. Information on EHD and its impact during the summer and fall of 2021 can be found at: gf.nd.gov/wildlife/diseases/ehd.

Hunters can report sick or dead deer to the NDGF by utilizing the wildlife mortality form at gf.nd.gov/wildlife/diseases/mortality-report.