Massive moose die-offs: is Alaska next?

Recent headlines have focused national attention on massive moose die-offs in the Lower 48. The mortalities may be due largely to winter ticks and other parasites. Is that something that could happen in Alaska? It will if nothing is done about it.

Like with the hottest fashions, Alaska is often the last state in the union to be hit with trends. But that doesn't mean they can't happen here. If any of the parasites decimating moose populations gain a foothold in Alaska, it could spell the end of moose populations and moose hunting as we know them.

Unbeknownst to many Alaskans, our state harbors homegrown ticks. I've seen them on squirrels and snowshoe hares, and I've heard reports of finding a lone tick on a dog or cat, often a pet that had been messing with a squirrel or hare. However, to the best of my knowledge, our native ticks tend to be selective about their hosts, and humans are not on the guest list.

Like other potentially invasive species, the bad sort of ticks – the ones that attach to humans – can hitch rides to Alaska on people or their pets. Dog ticks and Rocky Mountain wood ticks have been found on dogs (and people) recently arrived from the Lower 48 states.

Alaska has avoided dog, deer, moose ticks so far

"We historically have not had dog, deer or moose ticks in Alaska," said Dr. Kimberlee Beckmen, the Alaska Department of Fish and Game's veterinarian, "and we don't want them here." These ticks can carry Lyme disease, Rocky Mountain spotted fever, tick paralysis, Q fever, tularemia, and other diseases.

Some people just don't like ticks. My wife, for instance. Last summer, she and I were driving through California with my brother in the back seat. Unexpectedly, she emitted a blood-curdling scream, pointed to a tick silhouetted on her window, and demanded that I stop the car immediately. My wife is not a screamer. My brother, trying to be helpful, suggested that she roll the window down a few inches. He leaned forward and jabbed at the tick, which disappeared. Another scream.

I pulled over, she jumped out, and while she swatted at her clothing, I conducted a detailed and increasingly ostentatious inspection of the inside of the car and the gravel just outside the car door. I couldn't find the tick, but I knew she wouldn't climb back into the car until one was found. So I did what any good husband would do; I lied. I told her I saw the tick on the ground. She didn't believe me and called my bluff, demanding to see it. But my mendacious nudge provided just enough reassurance for her to slide gingerly back into her seat.


Recent outbreaks of moose parasites

According to the New York Times, Minnesota's moose have declined 75 percent since the 1990s. Moose hunting has been suspended. Similarly, the Christian Science Monitor reported Montana's moose populations have fallen about 40 percent in the past two decades, and moose hunting permits have been halved. Other states and Canadian provinces – for example, New Hampshire, Wyoming, and British Columbia – have experienced similar steep declines. In the Lower 48 states, only Maine has reported an increase in moose in recent years.

Moose population declines on a continental scale are not necessarily due to the same cause. In every state where moose are declining, the main culprits appear to be diseases and parasites. However, one common denominator seems to be climate change. Shorter winters, warmer summers, moister conditions year-round are more favorable to the spread of diseases and parasites.

New Hampshire's shorter winters have boosted numbers of winter ticks, a parasite that sucks blood from moose, leaving them weak and more susceptible to predators and cold weather. Estimates of the "tick load" on a single moose range as high as 150,000 ticks. A captive reindeer in Alberta, however, appears to have accumulated the record number of ticks, approximately 400,000. At more normal infestation levels of about 40,000 ticks, an average-sized moose, whose heart pumps about 34 quarts of blood, needs to replenish its entire blood supply every seven weeks just to feed the ticks. At these levels of infestation, hair loss is so extensive that the moose look pale from a distance. Heavily infested moose, known as "ghost moose," often can't browse fast enough to support their voracious parasites and die in midwinter from starvation.

In Minnesota, where the average midwinter temperature has risen about 11 degrees over the past 40 years, brain worms and liver flukes are suspected causes of the steep declines. Brain worms depend on white-tailed and mule deer as intermediate hosts. Deer are more adapted to warm weather than moose; thus, their populations are expanding north, bringing the worms with them.

Another factor in moose population declines, in addition to parasites, is heat stress. Moose don't do well in warm climates and, as air temperatures climb from decade to decade along the southern edge of moose distribution, even by a few degrees, it soon becomes too hot to be a moose.

Winter ticks

Beckmen knows more about moose parasites and diseases than anyone else in the state. She has monitored moose populations for existing and emerging diseases since 2002 and is familiar with the spread of parasites and diseases in the contiguous United States and Canada.

Beckmen has "great concerns" about winter ticks infesting Alaska's moose. Once limited to lower latitudes, winter ticks are crawling north, hitching rides from moose to moose. The ticks have been found in the Yukon on captive elk and increasingly are being found on moose killed by hunters. The only jurisdictions remaining where moose don't carry winter ticks are Alaska and, at the other end of the continent, the island province of Newfoundland. Moose were introduced to Newfoundland at a time of year when they were tick-free.

Alaska's moose are extremely vulnerable to winter ticks. Domestic livestock or dispersing wildlife could introduce the tick from the Yukon. The ticks aren't going to be stopped by the border patrol. Randy Zarnke, a retired Fish and Game wildlife disease specialist, has shown the ticks can survive an Alaska winter. Losing large patches of hair will also put infected moose at risk in an Alaska winter. "Without early detection," Beckmen said, "we will not have a hope of eradication before it becomes established." Unfortunately, detection measures, including late-winter aerial surveys to look for gross lesions or tick drags or tick trapping in the fall, are not being conducted because funds are limited.

Beckmen knows how badly winter ticks can affect a moose population. Consequently, she subscribes to the slash-and-burn strategy for controlling an emerging infestation, which has shown some success in other areas. To keep the ticks from spreading throughout the state, she said "there must be an intensive harvest of all calves and yearlings in the infected area in September and October." Winter ticks primarily target calves and yearling moose by ambushing them from shoulder-high plants. However, if the infestation is bad enough, she advocates killing all moose in the infected area to break the ticks' life cycle.

There's another reason for keeping winter ticks out of Alaska. Squeamishness. Winter ticks are not picky. The little bloodsuckers will attach to any mammal – including you – indiscriminately. That alone should be reason enough for Alaskans to want to keep them at arm's length, meaning no closer than Canada.

Brain worms, liver flukes, chronic wasting disease

Only three veterinarians in the state are capable of conducting a full necropsy on a moose, according to Beckmen. She is one of them. And Beckmen is also concerned about brain worms. They have seen no evidence of the parasite in moose examined to date. However, white-tailed and mule deer sightings are increasing in Alaska's Interior. Because deer carry brain worms and are an essential link in the worm's life cycle – and because any deer seen in interior Alaska is probably from the Yukon – Beckmen has attempted to convince state troopers and biologists to shoot any deer they see on sight. Wildlife biologists have worked hard to follow up on reports of deer in the Interior, but have been unable to collect any carcasses for Beckmen to necropsy.

Liver flukes, like winter ticks and brain worms, have not been found in Alaska's moose. Beckmen examines any abnormal livers that come her way; however, most hunters leave moose livers in the field, and their recollections aren't detailed enough for a diagnosis. "If liver flukes are introduced through cattle, moose will be susceptible, so we need to be continually vigilant," Beckmen said. Despite her concern, she is not authorized and doesn't have the staff or funding necessary to monitor parasites in incoming cattle.

Adding to her heartburn is the possibility of finding a very serious malady – chronic wasting disease – that is spreading through deer, elk and moose populations in the Lower 48 states and Canada. Chronic wasting disease attacks the brain, leaving affected animals drooling, staring blankly, staggering, and emaciated. It was first identified in the late 1960s in captive mule deer in Colorado. The disease is spreading across the continent like cancer in a vital organ. For several years Beckmen tested samples of caribou, deer, elk and moose brains from across the state; however, federal funding for this effort has ended and no one is actively inspecting wildlife for chronic wasting disease in Alaska.

For now, Beckmen believes winter ticks are the greatest threat to Alaska's moose. "They're on our doorstep in the Yukon," she cautioned, "and when it does come, it will be a management nightmare."

Beckmen didn't mention it but animals at high population densities have increased infectious disease and parasite transmission. Alaska's current intensive management strategy, otherwise known as predator control, is designed to create more moose and caribou for hunters.

Avoiding a management nightmare

Sport and subsistence hunters have been fighting over moose in Alaska for nearly a century. For much of that time, government agencies have engaged in various types of predator control to increase moose populations for hunters, which has upset and enraged people who appreciate predators as well as moose.

If there's one thing these feuding factions can agree on, it's that no one wants to see moose dying from parasites and diseases.


That's just what is happening in the contiguous states and Canada. Inevitably, when parasites and disease decimate moose populations, hunting is curtailed and moose predators like wolves and bears suffer losses.

Alaska's moose have always been less affected by disease and parasites than moose farther south. But diseases have a way of sneaking up on you. Will Alaska's moose be affected by the massive die-offs occurring in other states?

It's too soon to tell; however, it's much more likely to happen if Alaskans don't support funding to monitor these diseases and don't take personal responsibility for stopping the spread. Don't be the rancher who transports infected livestock or captive elk or reindeer into the state. Don't be the hunter who sees an abnormal liver and doesn't bother to bring back a chunk for testing. Don't be the pet owner who doesn't check your dog for ticks after a trip Outside. Don't be the Alaskan who doesn't report a deer sighting in Interior Alaska because you can't believe the animal could be chock full of parasites – a slim, graceful, doe-eyed time bomb.

Rick Sinnott is a former Alaska Department of Fish and Game wildlife biologist. The views expressed here are the writer's own and are not necessarily endorsed by Alaska Dispatch. Contact him at

Rick Sinnott

Rick Sinnott is a former Alaska Department of Fish and Game wildlife biologist. Email him: