Hard winters take a toll on deer

Thick snow crust can be a key to survival

Posted: Sunday, March 25, 2007

Dorothy Frary remembers dozens of carcasses on the beach.

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Frary grew up in Juneau, and as a girl in the mid-1960s, her family picnicked and beach-combed around Young Bay on Admiralty Island. Occasionally in the spring they'd find a winter-killed deer, but one year was exceptional.

"There were these big groups of carcasses," she said. "It was like they had all made it down to the beach, and then died. They were just bones and fur, and my dad explained they were winter kill."

Deep snow is a big problem for Alaska's deer. Deer put on body fat in the summer, and they depend on those reserves, and a meager winter maintenance diet, to get them through the cold times.

When snow gets chest-deep on deer, they expend a lot of energy getting around. It also makes finding nutritious food difficult, and predators are more likely to be successful.

The mid-1960s marked three consecutive years of record snowfall in Juneau. The 1970s opened with two consecutive winters of deep snow that also made the list of the top 10 snowiest years on record.

Those severe winters in the early 1970s resulted in significant deer die-offs in Southeast. In the aftermath, the hunting season and bag limit were scaled back. Hunting season was closed in the Petersburg, Kupreanof and Kuiu Island area of central Southeast Alaska.

Wildlife biologist Matt Kirchhoff said the deer population rebounded quickly in many areas, such as the ABC Islands (Admiralty, Baranof and Chichagof), because of a good crop of new fawns. That wasn't true on Kuiu Island and neighboring areas with lots of black bears and wolves, which eat the young deer.

Record snowfall isn't always a problem for deer. Snow can melt in midwinter, and often does. Snow that develops a crust thick enough to support a deer's weight is far less stressful than heavy snow deer must wade through. Deep snow that persists into spring is hardest on deer.

"You could have 200 inches one year and 500 another, and it wouldn't be as bad, depending on when it fell, and how it froze and how long it lasted," said biologist Neil Barten.

Different areas of Southeast offer better habitat and conditions than others, and these "microclimates" can vary tremendously.

Even before Juneau broke its the seasonal snow record with over 195 inches at the airport, Annex Creek, just 12 miles south of town and also at sea level, had 450 inches, more than 37 feet.

"That's why we have a hydro plant there," said Scott Willis, an engineer with Alaska Electric Light and Power.

All that snow hasn't accumulated. There's been melting and consolidation over the winter.

Those conditions are one reason why deer have never done particularly well on the mainland of Southeast. Sitka black-tailed deer range up the Pacific coastline from Southern British Columbia to Juneau, and have been introduced to Prince William Sound, Yakutat and Kodiak Island.

"This is about the northern extreme of their natural range," Kirchhoff said. "Juneau was as far north as they went before we started transplanting them. They do okay on the islands, but the winters are generally just too tough on the mainland."

Deer transplanted to Kodiak and its neighboring islands in the 1930s established a population that has thrived. But they've seen some tough winters, including this one.

"We started off with lots of snow, which rained off," said Larry Van Daele, a state wildlife biologist in Kodiak. Then temperatures dipped into the teens. "We lost most of the fawns early, and now the adults are starting to tip over," he said.

Van Daele said the Department of Fish and Game may consider reducing the deer hunting seasons and/or bag limits next fall to help the herds rebuild. That's what happened after the winter of 1998-99.

"That was a severe winter, not as much snow, but very cold," he said. "We lost 70 percent of the deer on the archipelago. Deer were literally windrowed in the kelp line. Since we don't have the trees for shelter, they head out to the beaches, but it's wind-swept and cold. They die and the tides wash them around."

Following the die-off in 1999, conditions were favorable and the population rebounded.

"They're pretty responsive and quick to rebuild, provided conditions return to normal," he said.

Van Daele plans to conduct mortality surveys in the next few months to assess the situation. That involves counting live and dead deer and looking at their body condition.

In Southeast, LaVern Beier and Neil Barten of Fish and Game are also hoping to gather information on winter kill. They will discuss options with other Southeast wildlife managers for collecting information about deer and the magnitude of the winter on their health and numbers.

That may involve airplane flights over parts of Chichagof and Admiralty Islands to count living and dead deer. Other ideas include landing and measuring snow depths in various habitat types, collecting and analyzing deer pellets to assess diets and nutrition, and assessing availability and degrees of browsing on shrubs such as blueberry plants.

• Riley Woodford is a writer with the Alaska Department of Fish and Game, Division of Wildlife Conservation, and produces the "Sounds Wild" radio program.

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