A moose is seen snacking on willows.

KALISPELL — Horseflies and mule deer might be playing a part in the demise of moose in the Big Hole Valley.

But, right now, no one knows for sure if they are really to blame.

Wolves and bears could be behind the low numbers of moose calves that don’t live to see their first birthday.

Once again, there’s not enough solid evidence to show that they’re truly the culprit.

There’s nothing simple in the solitary life of a moose.

That’s a fact a pair of Montana Fish, Wildlife and Parks biologists are learning as they follow three different populations of moose as a part of the state’s first-ever study focused on population dynamics of the largest member of the deer family.

The 10-year study is nearing its halfway point.

So far, the information the researchers have gleaned raises as many questions as it offers answers.

“They are a tough animal to monitor,” said FWP’s lead moose biologist Nick DeCesare. “They are really widespread and always found in low density. They often live in places that are hard to see from the air.”

While moose populations north of the border have been doing just fine, the species adapted for cold winters and summers filled with sunlight has been struggling on the southern edges of its habitat.

In Minnesota, biologists have seen one population totally disappear in the 1980s and '90s and another struggling to survive now from an onslaught of parasites, disease and predators.

Concern over the Montana’s moose population has its own long history.

Over the past couple of decades, state biologists focused on different regions across the state where moose live have noticed that they don’t see as many of the massive animals as they once did. As a result, in the last 10 years, moose hunting permits have dropped by about half.

Because moose don’t live in herds or migrate annually to winter or summering grounds, their populations are hard to estimate. DeCesare said the last estimate was made in 2006 when biologists whose areas included habitat used by moose were asked to make their best guess on their numbers.

“They came up with a number of about 5,000, but that comes with all kinds of caveats,” he said.

No one knows for sure why moose populations are struggling in some places and why they appear to be doing OK in others.

In an effort to shed some light on some of those mysteries, DeCesare and FWP research technician Jesse Newby have been following three separate moose populations as part of the 10-year study funded by the annual auction of a moose permit that's matched by federal Pittman-Robertson Act dollars.

The study includes capturing and collaring adult female moose with both VHF and GPS devices.

The goal is to have 30 collared moose in each of the three separate population segments located in the Cabinet-Fisher ranges, the Big Hole Valley and on the Rocky Mountain Front.

In the first five years, those collared animals have provided a glimpse in just how different the challenges are for moose across the state.

In the Cabinet-Fisher range in northwest Montana, the populations of the long-lived animal appear to be holding steady despite the fact that calves struggle to survive in the heavily wooded area. In the Big Hole, the calves are doing fine, but the adults are dying at higher rates than the other two places.

The Rocky Mountain Front was the only location where the population seems to be increasing slightly with both calves and adults faring relatively well.

“We are seeing three different stories playing out,” DeCesare said.

And inside of each one of those stories are even more interesting twists as the researchers have seen individual moose take off on long treks from the Rocky Mountain Front or make the fatal decision of trying the scale the Cabinet Mountains in the middle of winter.

“Moose have a very individual way of using the landscape,” Newby told FWP’s Region One Citizen Advisory Committee earlier this week. “They all have their own strategies. Sometimes those strategies don’t work for them.”

That individuality adds another layer to the challenge of understanding them.

A handful of places in Montana have seen annual efforts to survey moose from the air. Newby said overall that information shows a decline in populations in some areas. Even with that, there is enough variance in the samples that makes it hard to develop a solid trend.

In the long term, it’s going to take more than a couple of researchers to keep an eye on moose in the state

Hunters and others who spend a lot of time in the woods may be called on to help.

Coming up with a cost-effective way to gather more information Montana’s moose population is one focus of the study.

The researchers are looking at the potential of using information gathered from hunters during the annual telephone surveys to gain some additional insight on where moose are being seen. In the past, hunters have also provided similar information at game check stations.

“By the time we get to the end of the study, we would like to have a toolbox developed that would let us effectively monitor the moose population,” Newby said.

That might include retooling some of the surveys from the air, but it’s going to be boots on the ground that probably will make the most difference.

“Hunters have generally been eager to help,” Newby said. “We get a lot of information from moose hunters. … We are assessing right now how it’s all going to work. Once we’re done that, we will need to make a push out there to ensure that people will give us a heads-up when they see a moose and provide us with information like when and where.”

When it comes to finding the cause of mortality for both calves in the Cabinets and adults in the Big Hole, both researchers acknowledge that it’s not going to be easy.

DeCesare said they had considered capturing moose calves and putting on devices that could track their movements. After learning about the deaths and abandonment that occurred in other places when researchers attempted that strategy, they decided against it.

“We didn’t want to take that chance,” he said.

Discovering what’s killing adult moose in the Big Hole hasn’t been simple either.

An arterial worm called Elaeophora schneideri is a suspect. The worm is carried by mule deer and passed on through horseflies. It’s been found in large numbers in moose found dead in the Big Hole.

Isolating that one parasite as the cause of mortality is a challenge, Newby said.

When a moose was found dead in a rancher’s pasture, the researcher thought maybe they finally had what they needed to determine a cause. The fresh carcass was hurriedly winched onto a trailer and rushed to a lab where 50 of the arterial worms were extracted.

“When we got the report back, we discovered the moose was suffering from a multiple of bacterial issues,” Newby said. “There were a lot of things going on with that moose. Finding the smoking gun is a problem in even the most ideal conditions.”

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Northwest Montana Reporter

Northwest Montana reporter at the Missoulian