Snow doesn’t make winter merry for moose

Ungulates struggle as white stuff piles up

Posted: Friday, January 12, 2007

 

  A yearling moose browses through snowy bushes in Soldotna on Thursday morning. The deeper the snow gets, the harder life becomes for the peninsula's most common ungulate. Photo by M. Scott Moon

A yearling moose browses through snowy bushes in Soldotna on Thursday morning. The deeper the snow gets, the harder life becomes for the peninsula's most common ungulate.

Photo by M. Scott Moon

When the snow grows deep, skiers, children armed with sleds and snowballs, and other outdoor recreationists happily frolic outdoors. But not everyone cheers at the sight of more white, and if you watch the wilderness and roadsides during this snowy winter you may see a sullen-faced character not at all happy about the snow.

As snow depth grows, moose expend more energy to move around, face a steeper battle against malnutrition and place themselves in danger as they walk along roads and highways to avoid the snow.

“It’s kind of a multi-pronged impact on them,” said Thomas McDonough, an assistant area management biologist with the Alaska Department of Fish and Game in Homer. “It covers up food, making it unavailable and it’s energetically expensive to plow through snow. So they have to waste more energy plowing through snow to find scarcer food sources. It’s kind of a double whammy.”

Deep snow has accumulated in the Homer area this winter, and if snow depths continue to build, a significant number of moose could die due to malnutrition, he said.

McDonough said snow depths have not yet reached a critical threshold, but they are not far from it and we still have several more months in which snow could continue to build.

Research suggests moose mortality rates due to malnutrition reach a threshold point when snow depth gets to about one meter deep, and hit calves the hardest, he said.

“The calves in that level of snow depth really have difficulty moving around and they tend to have a really high mortality,” he said.

Snow depth is not as great in the Kenai and Soldotna area as it is in Homer. But any time snow gets above the mid-leg level, moose feeding and movement patterns change, said Tom Lohuis, Kenai Moose Research Center director.

While deep snow always is a concern with respect to moose, there is little management biologists can do to help.

“It’s not really a situation where we can do anything about it,” said Lohuis. “And supplemental feeding is really not the way to go.”

The food a moose can digest changes from one season to the next and if a moose eats the wrong food at the wrong time its digestive system can become stopped up with undigestible food, using valuable space and energy that could instead be used to process digestible food.

A moose’s digestive system harbors a garden of bacteria and insects, a collection of critters known as the moose’s mirco-flora. Without this micro-flora a moose could not break down cellulose to extract nutrients from plant matter.

In the summer, when a moose eats lots of aquatic plants and other leafy vegetation, a moose’s micro-flora is dominated by insects and bacteria that break down moist greens quickly. In the winter, on the other hand, a moose’s micro-flora is dominated by insects and bacteria that slowly but efficiently break down woody vegetation, a primary component of their winter diet.

But the balance in a moose’s micro-flora adjusts gradually and cannot adjust to sudden changes in the moose’s diet.

So although feeding a skinny winter moose may seem merciful, it can lead to starvation and is illegal.

“If you provide an amount of very, very rich feed in a short period of time the rumen bacteria can’t handle it,” Lohuis said. “They’re adapted to lower-quality forage.”

Patrice Kohl can be reached at patrice.kohl@peninsulaclarion.com.



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