One of the animals most often associated with Alaska is the moose. Yet here in Southeast we have relatively small populations of moose, and they are grouped in only a few scattered areas. Why is that?
To find out I interviewed Neil Barten, area wildlife management biologist at the state Department of Fish and Game, Division of Wildlife Conservation, in Douglas.
Moose only began showing up in Southeast in the 1920s and '30s, Barten said. Most of them migrated from Canada along major river systems - the Stikine near Wrangell and Petersburg, the Taku near Juneau, the Chilkat near Haines, and the Alsek near Yakutat.
Moose were introduced into Berners Bay in 1958 and 1960 by the Department of Fish and Game and the U.S. Fish and Wildlife Service. And during the past 10 years increasing numbers of moose have been appearing around Gustavus.
The presence or absence of moose populations is related to vegetation, Barten said. In summer, moose in Southeast eat a variety of plants - horsetails, highbush cranberry, aquatic vegetation such as pond lilies, and sometimes a little blueberry. But in winter they survive almost exclusively on the twigs and branches of willows, which grow primarily in river valleys or where glaciers have receded recently.
"Almost annually someone on Chichagof Island reports seeing a moose or finding the remains of one," Barten said. "But Chichagof is not good moose habitat. It's mostly forest. A few moose might survive there, but the surrounding habitat is better for deer and poor for moose."
In Interior Alaska, where moose are more common, forest fires periodically burn the boreal forest and recreate the early stages of vegetative succession that provide good habitat for moose, Barten said.
Here in Southeast, we don't have forest fires, and our spruce-hemlock forests do not cycle in that way. The land in Southeast also is rising (in some areas an inch or more per year), partly in response to the retreat of glaciers, partly due to tectonic forces. In the natural stages of vegetative succession, the willows that grow on flats and along scoured and braided river channels are giving way to cottonwoods, and then to spruce-hemlock forests.
"You can see the changes right now," Barten said. "The pilot who flies most of our aerial moose surveys has been flying in Southeast for over 40 years. Some of the places where he could land on grassy flats 25 years ago are now grown up to more than 25 or 30 feet high. Short of an earthquake, glacial advance or a major flood, most of Southeast will change to habitat not favoring moose."
The Department of Fish and Game manages moose in Southeast primarily by adjusting the numbers hunters are allowed to harvest. Biologists count moose from the air in late fall. They track the ages of moose taken. (Under most of the registration and drawing permits required for moose harvest in Southeast, successful hunters are required to turn in the moose's lower jaw and teeth.) And they collect information from hunter "report cards" that catalog where people hunted, for how many days, and with what success.
"If it takes hunters just a few days to be successful, we can assume a moose population is quite dense," Barten said. "If the number of days increases and harvest numbers decrease, we'd say there are probably a lot fewer moose, so we would set harvest levels accordingly."
Barten explained that moose populations rise and fall due to a number of factors.
"In the 1960s," he said, "there were about 2,500 moose around Yakutat. Now there are probably 600 to 800. Originally they were on a high plane of nutrition. Cows were having lots of twins, and wolves and bears were not taking very many calves. That's changed. That area also suffered a series of bad winters, when many moose died."
Things are just the opposite around Gustavus. Moose moved in there about 15 years ago, Barten said, and the population has grown rapidly.
"Now we're worrying about that population being too big," he said. "They seem to be foraging beyond what the habitat is capable of sustaining. The willows are eaten down to the size of my finger. They're likely to start dying, and the moose will run out of food. We're trying to get that herd down from its present levels of probably 300 to 350 to about 200, partly by authorizing the harvest of 10 cows this fall.
"We know wildlife populations cycle," Barten said. "It's only humans that don't want to deal with cycles. We want everything all the time. ... A hundred years ago there weren't any moose in Southeast Alaska. In another 100 years, there might be very few."
The Juneau Audubon Society meets at 7:30 p.m. the second Thursday of each month at Dzantik'i Heeni Middle School. Contact members at email@example.com.
Juneau Empire ©2013. All Rights Reserved.