Brain worm in ND Moose

Vollmer

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Brain worm causes decline in eastern moose population

DOUG LEIER N.D. Game and Fish Department

It’s been interesting to watch and learn about the movement of moose within North Dakota. In the not-so-distant past, moose were mostly found in the wooded Turtle Mountains or Pembina Gorge of north central and northeastern North Dakota.

In the past 12 years, moose numbers have declined in the Pembina Hills area. Aerial wildlife counts conducted by Game and Fish biologists note that about 250 moose were spotted in that region in 1995, but only two cow moose were observed in the survey areas flown in 2017.

Moose numbers began to increase in the western part of the state in the mid-2000s. The Anamoose and Lonetree Wildlife Management Area, Williston and Kenmare areas all have seen increases in moose populations since then, and the area with the highest moose density is no longer the Pembina Hills — it is now the Upper Missouri River area near Williston.

So why is the moose population seemingly moving west? Jason Smith, Game and Fish big game management biologist, said these 1,000-pound animals are being affected by a creature the size of a single hair.

“The primary reason for the decline in moose populations on the eastern side of the state is brain worm,” he said. “As you move west, the risk of transmission of brain worm drops off, and we’re seeing that same pattern in Canada.”

Brain worm is a parasite often found in white-tailed deer, and it’s spread through the deer’s feces.

The worm larvae are picked up by snails or slugs, which are then accidentally eaten by ungulates like deer as they graze, according to James Maskey of the University of Mary.

In whitetails, Maskey said the worms migrate through the deer’s body to the spinal column, and they travel along the outside of the spinal cord to the surface of the brain, where they survive, reproduce and keep the cycle going. While the worms don’t pose significant health issues for whitetails, they may cause death in “accidental hosts,” such as moose, elk and mule deer.

Maskey said in those animals, the worms burrow into the spinal cord, brain stem and the brain itself, instead of traveling along the surface. That can cause neurologic problems that eventually lead to death.

The wetter climate in the eastern portions of the state are necessary for survival of the slug and snail hosts, Maskey said. Farther west, the climate is a bit more arid, and the snails and slugs can’t survive — and because of this, the brain worms aren’t spread from one animal to the next.

No one really expected such a transition in North Dakota’s moose population, but it’ll be equally as interesting to see where they are — or aren’t — another 20 years from now.
 


LBrandt

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Its been awhile but we had a young bull with that down here. Seen him in the Government pasture walking in circles about 50' in dia.Called warden and I think he put him down.
 

Paddledogger

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While laying at home recovering from back surgery I was watching Alaska Troopers show. One of the troopers responded to a call of an moose with this brain worm. It is just crazy how the young bull moose could only walk in circles. This moose had created such a path on the edge of the trees that the Trooper estimated that this moose was probably there walking in circles for a day or two. Obviously, he did put the animal down. The Trooper also explained how the moose population has been affected and how they get it. Sounds like the worm is pretty aggressive.
 

Allen

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About 20 years ago, I saw a WT buck with the same symptoms near New Town. I called the warden but never did hear back on if he found him and put him down.

On a different note, the brain worm may be why we don't see nearly as many moose in the east and north as 20 years ago, but I don't think the moose themselves have figured out that they need to head south and west to avoid the worm. That would likely be something different, unless they are a lot smarter than we give them credit.

Anyone been seeing any moose out getting their college degrees in biology?
 


Obi-Wan

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Here I thought this was a thread about Heidi.

Back in the mid 90's I went with the father in-law who had a moose tag up in the Wahalla area to help him with his moose tag. While up in that area we saw quite a few moose and elk. Back then they had Elk tags for that area do they still have an elk herd in the area large enough to have a season?
 

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