BOISE, Idaho — Moose are one of the West's most majestic animals. Seldom seen in Oregon, with only around 50 living in the state, and in neighboring Idaho, moose are under threat.

A sought-after hunting opportunity in Idaho — it's illegal to hunt moose in Oregon — dwindling moose numbers prompted Idaho Fish and Game to drastically cut the number of moose tags in February. In 2019-2020, there will be only 634 moose tags available each year, a 22% decrease from 2017-2018, which also saw an 8% reduction compared to 2015-2016. The panhandle region of Idaho saw the largest reduction in 2019-2020, a 45% reduction in moose tags and the elimination of antlerless tags.

But why exactly moose populations are declining is unknown.

"We have seen the most severe declines in northern Idaho and southeast Idaho, but we don't know exactly why they are declining," Hollie Miyasaki said in an interview with the Idaho Statesman. Miyasaki is a moose, bighorn sheep and goat biologist with Idaho Fish and Game.

Idaho Fish and Game also does not know exact moose population numbers, but estimates there are 10,000 to 12,000 moose in the state.

Oregon Department of Fish and Wildlife officials believe an estimated 40 to 50 adults and calves live in Oregon. The moose reside in the Blue Mountains north of Elgin, in the northeastern part of the state.

To estimate moose populations, Idaho Fish and Game relies on harvest information.

"It is hard to do a survey because moose do not herd up in the winter like deer or elk. To estimate populations, we use harvest information like hunter success rate, or the percent of hunters who successfully harvested a moose, hunter effort, or the number of days to harvest a moose in a hunt, and antler spread of harvested moose," said Kara Campbell, regional wildlife biologist for the panhandle region with Idaho Fish and Game.

State biologists use these three harvest metrics to estimate the size and age of moose populations in different hunting units across Idaho.

"Biologists and hunters have both reported declines in recent years, leading to the big cut in moose permit levels this year," Campbell said.

ODFW staff have been monitoring Oregon moose distribution and numbers since 2005 and have used helicopter surveys since the winter of 2012 to estimate moose populations, the agency reported in April. The number of moose observed during these surveys ranges from 12 to 18 individuals, because moose are difficult to see due to their solitary nature and preference for dense timber and vegetative regrowth. For example, during the 2018 aerial survey the ODFW visually located only one of six radio-collared moose in the survey area.

Annual moose calf growth appears to be good, the ODFW noted in an April field report; however, the population does not seem to be increasing and may have actually fallen over the last several years.

On a positive note, the report said, moose are beginning to distribute more broadly. Historically moose have been found mainly in the Blue Mountains in the ODFW Wenaha Wildlife Management Unit. More recently, ODFW has found moose in the far northeastern part of the state on the Idaho border. In addition, a large 80,000-acre fire in 2015 and recent logging are expected to make habitat more favorable for moose.

Why the decline?

Wildlife biologists do not have clear answers, but the likely suspect is a combination of habitat loss, ticks and predators.

"Idaho moose live in most of the state except the southwestern portion and around urban Boise. Moose range has been expanding in the south-central region, where we typically would not see good moose habitat, but decreasing in northern Idaho, where we typically see good moose habitat," Campbell said.

Good moose habitat includes plentiful forage and shade from the sun.

"Recently burnt forests with new growth are great moose habitat. But wildfire suppression reduces good moose habitat. We need wildfire to open up dense forests. Old growth forests are too dense for moose," Campbell said.

Wildfire is a natural part of many Idaho ecosystems, but with homes and lives at risk, state and federal agencies promote wildfire suppression. Until recently, the U.S. Forest Service suppressed and controlled all fires rather than allowing natural forest fire cycles. Without thinning and new growth caused by wildfires, moose have less feeding and breeding habitat.

According to Campbell, moose populations are highest in areas 40 years after a major wildfire.

But habitat loss is not the only probable cause of moose decline. Tiny ticks also could be a big problem.

"Moose are susceptible to ticks. Moose are not good groomers," Campbell said. "High tick loads used to die off in the winter, but with warmer winters, we don't see tick die-off that we used to see. So moose can accumulate ticks at high loads, up to 10,000 ticks per moose."

According to Campbell, these ticks can spread disease and ticks gorging on moose blood meals can weaken the moose, making it vulnerable to predation.

"Predation is an ongoing research area," Campbell said. "Moose rely on deep snow to avoid predators in the winter. We don't always have deep snow. Without deep snow, then predators like wolves and mountain lions have an advantage over moose."

Climate change brings a mixed bag for moose. The U.S. Environmental Protection Agency predicts hot, dry summers and warm, wet winters for Idaho into the future. Hot, dry summers lead to more wildfires and possibly more moose habitat, but warmer winters with smaller snowpacks put moose at risk of tick infestations and predation.

Understanding moose populations

Idaho is not the only state seeing moose declines. In Utah, for example, moose reached a record population size of 4,000 in 2005, but the population dropped to the most recent estimate in 2017 of 2,650 animals.

"We are not alone in our concern. All of the Western states are looking at this," Miyasaki said. "In fact, we just had a big workshop and are working on a moose management plan for the next few years. Hopefully that plan will come out later this year."

Idaho Fish and Game officials met with representatives from Utah, Wyoming, Washington and Oregon to create regional and state-specific moose management plans.

Idaho Fish and Game is ramping up a large moose study to look at the multiple factors contributing to moose decline. The project will radio collar moose to understand where they go and how they die. Oregon already monitors six radio-collared moose to determine distribution, movement, and mortality. ODFW plans to radio-collar three more this year.

"We are radio-collaring moose in four different areas across the state," Miyasaki said about Idaho's plan. "To put a radio collar on a moose, we use chemicals to sedate the moose from a helicopter, then we land, put a radio collar on the moose and do health tests. We can use the radio collar to tell when the moose dies, then we locate the animal and collect information about how that moose died."

This radio collar research combined with moose hunt data will help identify the biggest causes of Idaho moose decline and dictate actions to protect the moose populations. Hunters have been asked to submit DNA samples in the past but Fish and Game plans to request more tissue samples next year, Campbell said.

Moose population declines mean less moose hunting tag availability, a conservation strategy largely supported by hunters.

"Comments from the public have been extremely supportive. Some hunters said we should have done this sooner," Campbell said. "People understand this is not just a local concern. It is a concern across the region. Moose is an iconic species we all want to conserve."