Montana EHD outbreak is biggest in recent memory


Mar 11, 2001
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Deer disease outbreak biggest in memory.

Mark Henckel/Billings Gazette

It’s an outbreak of EHD in size and scope unlike any other in recent memory.

From the Wyoming border to Canada, covering roughly the center one-third of the state, this deadly disease has cut a wide swath across Montana this year.

It has left a death toll among white-tailed deer in the thousands – perhaps the many thousands – in its wake.

In fact, deer hunters heading to Central and Eastern Montana for Sunday’s opening day of the general deer and elk season may find more dead whitetails than live ones.

EHD, the short, pronounceable, easy-to-spell name for epizootic hemorrhagic disease, is a fatal deer virus spread by a biting midge. It’s similar to bluetongue in sheep.

EHD hits whitetails the hardest, though it is rarely found in mule deer. Outbreaks usually begin sometime in the heat of August and end with the first hard frost of fall, which kills the midge that spreads the disease.

But rather  than affecting just a small area of a drainage or two as it does in many years, Montana Fish, Wildlife and Parks biologists are finding it in whitetail habitat almost everywhere at lower elevations east of the Continental Divide and roughly west of a line from Miles City to Glasgow.

Plenty of reports
Here are some of the reports from FWP personnel:

From Jay Watson at Billings: “We had reports from the Park City area real early on. We had reports from as far up as Joliet on Rock Creek and at least up to Bridger on the Clarks Fork. We had them from Worden and Pompeys Pillar on the Yellowstone and from the drainages near there. We also heard of it on the Bighorn.”

From John Ensign at Miles City: “The worst of it is right around Hysham on the Yellowstone. As you go further west, it’s pretty bad. As you go east toward Forsyth, it starts to diminish. We’ve had reports up by Cohagen, by Timber Creek near Brockway, by Birney.”

From Pat Gunderson at Glasgow: “We’ve had it along the entire length of the Milk River. We’ve got dead whitetails here around Glasgow, but not like they’ve got from Malta west. It’s more severe west of Malta. It’s also affecting feeder streams to the Milk. The hunters are talking about dead whitetails in the feeder streams.”

From Tom Stivers at Lewistown: “It came up the Missouri and the Musselshell and the drainages off of them like McDonald Creek, Armells Creek, Flatwillow Creek, Arrow Creek. All the drainages from Eddies Corner to Judith Gap, the Ross’ Fork of the Judith, it ran up into there. It was real widespread.”

From Gary Olson at Conrad: “We’ve had lots of reports on the Marias as far up as north of Valier. We’ve got it in the lower Teton River from Dutton downstream to Loma on the Missouri.”

It’s as widespread an outbreak of EHD in Montana as anyone can remember.

Deer loss
No one can calculate the total number of white-tailed deer lost to the disease this year. But biologists do say it’s extremely heavy in some areas and somewhat lighter in others.

Said Stivers of his area near Lewistown, “Off the cuff, in areas that were hit hard, I’d say it took 80 percent of the whitetails. We still have whitetails. But where it was really noticeable was out in the flatter drainages where whitetails had gotten more numerous in recent years.”

Olson said, “On the Marias, a landowner walked the equivalent of a center-pivot (irrigation system) – about a quarter-mile – and counted 15 dead whitetails. I’m estimating that we probably lost at least 50 percent of the whitetails based on what I’m hearing.”

At Billings, Watson said, “It’s real spotty. I walked an island for almost four hours north of Worden and found three dead deer. I walked another island by Pompeys Pillar for about the same period of time and found 17. There are places that got hit hard. Then there would be a stretch where it wasn’t hit as hard. Then there’d be a pocket with real high mortality.”

Disease factors
Biologists know that a biting midge spreads the disease. They know it typically begins in late summer. They also know that it typically ends with the first hard frost of fall that kills off the midges.

The longer the disease runs into fall until that first hard frost, the more it spreads. In some parts of the state, it took until last week for that first hard frost to arrive.

But other factors involved as to why this disease crops up in one area and not in another are a bit harder to pin down.

Stivers said much of the EHD in his area of Central Montana is related to elevation.

“It probably didn’t get into the foothills of the Big Snowies,” Stivers said. “It got up to about as high as 4,600 to 4,800 feet. Above that, it might not be right for the midge that spreads the disease.”

“Usually, when we have EHD, what gets hit is the lower Yellowstone from Glendive to Sidney, but that isn’t happening this year,” Ensign said. “We’ve heard reports of some dead down there, but not a bunch. It’s scattered.”

Also, the area where the disease is found in the state mirrors the portion of Montana that was hit hardest by drought conditions.

“In the areas where we had more moisture, it may have kept the whitetails more dispersed. One of the lynch pins of the disease is the higher densities of deer,” Ensign said. “Those are the situations where the deer are hit the hardest. The eastern parts of our region have had more moisture, so regionwide, it hasn’t been too terrible.”

Gunderson said the same about far northeastern Montana. “A reasonable guess is that we have been wetter here. The animals are not as concentrated as they were further west.”

People concerned
Despite the severe outbreak, hunters will still find whitetails in most of their old haunts, though there may not be as many deer this fall.

“In the core whitetail habitat, there are still going to be good numbers of whitetails,” Stivers said. “This is great whitetail country and there are still going to be whitetails for people who want to go after them.”

On the other hand, as hunters head out this weekend and begin hiking through whitetail areas, they are likely to find dead deer and it’s certainly going to cause some level of alarm.

As Olson put it, “Of the people I’ve talked to, they aren’t panicked, but they are concerned.”


Mark Henckel is the outdoor editor of The Billings Gazette. His columns appear Thursdays and Sundays. He can be contacted at 657-1395 or at

EHD info

EHD hits some deer harder than others and it may kill some quickly, while others may die later, according to Charlie Eustace, regional wildlife manager for Montana Fish, Wildlife and Parks in Billings.

Often, dead deer are found near water. At other times, they may be further away from the nearest water source.

“There’s no one-size-fits-all,” he said. “In many cases, the head and tongue may be swollen. There may be some bloody froth coming out of the nose. Internal examination may show that it would look like measles on the internal organs because of the tiny hemorrhages on the organs.

“On the quick ones, it would be about three days from when they got the disease until they died. Then again, it could drag on for weeks,” Eustace said. “We’ve had some people who have reported emaciated deer – deer that looked very thin. Normally, that isn’t associated with EHD, but apparently there are several levels of the disease they can get and at lower levels, they can lose a lot of weight.”

People don’t have to worry about contracting the disease themselves.

“People don’t need to be extremely fearful,” Eustace said. “They’re not at risk from handling an infected deer or eating from an infected deer with EHD – which is different from Chronic Wasting Disease.”

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