A day in the life of a moose

Gustavus moose teach researchers about winter survival

Posted: Sunday, May 13, 2007

Biologist Stacy Crouse stood a few dozen yards from the big cow moose and her calf, scrutinizing their activity through binoculars. Without taking her eyes off her subject, she repeated one word over and over.

Sound off on the important issues at

"Five, five, five, five."

Crouse was counting every bite of food the cow moose was taking, and I was recording her observations on a hand-held computer. A stopwatch was ticking, the type of forage was entered, and it all was logged in.

It was late winter, and wind had blown most of the snow off the Gustavus forelands, about 40 miles west of Juneau. The hungry moose was eating horsetails, a low-growing plant not usually exposed in winter.

Crouse was researching moose nutrition, and these moose were ideal candidates. She's based at the Kenai Moose Research Center near Soldotna, and often works with tame moose, bottle-raised subjects that tolerate close human contact.

There she's able to closely observe moose foraging throughout the year and develop the methods to answer critical questions: how much food moose eat and how much nutrition and energy they derive from their food.

She's examined closely cropped shrubs in the field to learn how the herbivores affect their food sources and how this influences future foraging.

This Gustavus work with wild moose is related to a suite of other moose studies initiated by biologists Kevin White and Neil Barten.

Alaska Department of Fish and Game researchers have captured and radio-collared about 30 moose on the Gustavus forelands, and White and Crouse examined these animals in the fall.

They compared their condition before and after winter, hoping to better understand how moose survive. They are also monitoring the vegetation, to see how the habitat survives the moose.

When Crouse can get close enough, she records what the animal is eating and how long it spends chewing on it. When she can't, she looks at general activity: the moose is foraging, or lying down.

"It's basically a day in the life of a moose," she said.

After an hour of foraging, the moose and her calf bed down, and Crouse logs them in as "resting."

It's a cycle for the moose during winter: feed and rest, feed and rest. The resting is largely digesting, as bacteria and protozoa in their digestive tract break down the dry willow twigs and horsetail stems, providing a fraction of the energy these moose need to get through the winter.

The remainder is supplied by fat and protein reserves the moose put on last summer and fall.

"As often as I can, when I can get close enough to see them actually harvesting bites, then I'm recording every bite they take," she said. "I can go back and see how many bites they harvested in what amount of time. Then I can measure the bite size so I know how much biomass they're removing with each bite, and I know the quality of that bite - so then I go back and calculate their nutritional intake per unit time of foraging.

"And those are the kinds of things you wouldn't know unless you were watching them actually harvest the plants."

Moose began colonizing this coastal area near Glacier Bay National Park in the late 1960s, and the population grew rapidly. Biologists estimate 400 to 500 moose live in the area, a density approaching five moose per square kilometer.

Judging from their body condition and productivity, and their impact on the habitat, it looks like that number is close to the maximum carrying capacity.

It's a dynamic system influenced by a variety of factors, including the condition of the forage and how the vegetation responds to browsing, the impact of predators, the productivity of the moose, and the weather.

The Gustavus moose hunt is popular with hunters in northern Southeast Alaska, and the harvest has been liberalized recently. An antlerless hunt has taken place every fall for the past several years in addition to the regular hunt for bull moose.

"They have an overabundance of moose here, and the department is trying to reduce it, to bring body condition and productivity back up," Crouse said. "This population appears to be nutritionally limited."

Crouse said her research ties in nicely with the management objectives. "As the herd size is reduced - and as I'm observing these animals forage - we can see if the population's condition is changing as the herd size goes down.

"Are we seeing a response in productivity and body condition and nutritional intake? Then we'll get a better idea what the potential carrying capacity of the area is - how many productive moose it can support."

Crouse has worked with moose on the Kenai Peninsula and in Southcentral Alaska. She said the Gustavus population's behavior is unique.

"You have such a high concentration of moose in such a small area in the forelands, and it's so accessible. Plus the tractability of them, they'll tolerate me watching them - not all of them, but there's a few that'll let me watch them."

In summer, moose disperse over a wide area that includes Glacier Bay National Park to the north and west and portions of the Chilkat Mountain Range to the north and east.

But in winter, the population favors the low elevation areas near the community of Gustavus, and the moose concentrate on the forelands. Crouse has identified nine or 10 moose that tolerate her presence and behave normally, and she's focused on those.

"I don't want to watch an animal where I'm influencing the behavior. That defeats the purpose," she said. "I want animals that will carry on as moose and behave naturally."

In winter, the animals tend to group together where the forage is good, and sometimes that creates an unfavorable dynamic.

"It really depends on who they're hanging out with," she said. "Sometimes they'll get in a crowd with a skittish moose and one will run, and then they all tend to run."

Early in winter, moose mainly eat the toothpick-size twigs of willow, the growth from the previous season and the most nutritious part of the plant. As winter progresses, the moose return and eat the pencil-size twigs and small branches.

"They come through and really annihilate the willow community here," Crouse said.

During the next bout of foraging, biologist Kevin White arrived with a capture kit and dart gun. At dusk, as the cow prepared to bed down, White sedated her and the two researchers carefully examined her.

An ultrasound provided a look at the layer of fat under her skin. They took samples of blood and tissue and swapped out her tracking collar for one with fresh batteries.

A reversal drug was administered, and within a few minutes the cow was on her feet again. Her calf, watching from a nearby in a patch of shore pines, rejoined her, and the pair ambled off.

• Riley Woodford is a writer with the Alaska Department of Fish and Game.

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