Some Montana moose just fall over, dead

Several years ago, Montana Fish Wildlife and Parks began hearing from sportsmen that there didn’t seem to be as many moose in the woods as there used to be. So FWP decided to embark on a 10-year study of moose in Montana.

Moose have seen marked declines in other regions of the Lower 48. Populations have fallen so dramatically in states like Minnesota that a subspecies of moose there has been petitioned for listing under the Endangered Species Act.

Five years in, biologist Jesse Newby has begun to unlock some of the secrets of Montana’s moose, but there’s still plenty learn as to why some populations are doing OK, while others are in decline.

Newby has been examining moose populations in three separate areas of the state — the Cabinet-Fisher region, the Big Hole Valley and the Rocky Mountain Front, south of Glacier National Park.

To initially gather data, FWP used telephone surveys of hunters to determine where moose populations are in the state — moose aren’t always where one would expect them. For example, there’s a small population up along the Canada border near Cut Bank and another in Northeast Montana near North Dakota.

But the greatest concentrations of moose are in the western half of the state. Moose here are a subspecies — the Shiras moose — and are smaller than their northerly cousins. The Shiras moose lives along the Rocky Mountains as far south as Colorado.

Moose require cold weather — at temperatures above 30 in January they’ll become heat stressed and in the summer months, they don’t like temperatures much higher than the 60s, Newby noted.

The big creatures have ways to moderate body temperatures, however. Those long legs are aptly suited for wandering around in bodies of water to keep them cool. They’ll also seek higher, cooler terrain as well.

In order to track the lumbering critters, Newby has radio collars on select females in each area. Currently, biologists are tracking 81 moose from the three regions.

The results have been fascinating.

Newby said the initial theory was that moose sought higher terrain in the summer months and lower terrain the winter months. But that hasn’t always proven to be the case. Based on data from the radio-collared cow moose, they can also be high in the winter and low in the summer or vice versa. It often depends on the moose. There were some moose on the Rocky Mountain Front, for example, that spent almost all their time in one swamp on the Pine Butte Reserve, while another moose from the Front, known as moose 433, wandered all the way up to Canada and was never found again.

One female moose crossed the Cabinet Mountain range in the winter — Newby had a photo of her high in the cliffs. She was able to make it down, but not without suffering a broken leg, which ultimately ended her life as she died of starvation.

Each population has different dynamics. Moose on the Front have a high calf survival rate, while moose in the Cabinets have a lower calf survival rate — about 73 percent.

The Cabinets have a lot of predators — wolves, black bears, grizzlies and mountain lions. Black bears have been known to be a significant predator of moose calves. Wolves also prey on moose. One interesting facet, Newby noted, is that a moose that reaches maturity has almost no mortality from predation.

Newby put up remote cameras to capture images of predators in all the regions. To date, the cameras have collected 4.5 million images and of those, about 69,120 were wildlife.

So far, the study has found that the Front and Cabinet-Fisher moose populations are stable, but the Big Hole population has been showing a decline.

“A lot just tip over,” Newby said.

They literally fall over dead.

Moose are susceptible to a host of diseases and parasites — many of the pests also infect ungulates like deer and elk, without much effect — but moose are less tolerant.

In the Big Hole, they found dead moose were infected with Elaeophora schneideri, a nematode that is transmitted by horseflies. The worms get in the carotid artery and if there’s enough of them, they can cause death. Infestations also lead to cropped ears because body blood flow isn’t sufficient, and blindness.

One cow died in a pasture where biologists where immediately able to load into onto a pickup truck and then do a full necropsy on it. While the moose was infested with the worms, the actual cause of death was a multitude of factors, Newby noted.

“Even under ideal circumstances finding a smoking gun is problematic,” he noted.

In other regions of the country, brainworm — another parasite that’s transmitted by deer — and winter ticks have proven fatal to moose. The Front’s moose have winter ticks — a single moose can have as many as 15,000 of the blood-sucking insects. But so far, the ticks don’t seem to be impacting populations. Tick infestations in other areas of the U.S. have ranged as high as 30,000 to 50,000 ticks per moose. In those regions, moose can’t make up the lost blood supply.

Newby noted that there’s still a long way to go with the study.

Each year researchers write annual reports — they can be viewed on FWP’s web site at http://fwp.mt.gov/fishAndWildlife/diseasesAndResearch/research/moose/populationsMonitoring/default.html