Northeast Region
Conserving the Nature of America

How does an unusually warm winter affect animals?

Animals in the Northeast are well adjusted to cold weather. Whether they migrate, hibernate or bulk up, each individual species has their own way of coping with the cold. Have you been wondering what animals do during warm winters like the one we’ve had this year? Here are a few examples.


Snow geese in flight. Credit: USFWS
Snow geese in flight. Credit: USFWS

Snow Geese

Snow geese usually live and breed in Canada and Alaska, and they prefer to winter in the warmer climates of the southern U.S. and Mexico. During this exceptionally mild winter, U.S. Fish and Wildlife Service biologists report that as many as 10,000 snow geese have migrated only as far south as the mouth of the Chester River in Maryland, where snow geese haven’t been seen in 18 years.

 


Red knots and horseshoe crabs on a Delaware beach. Credit: Gregory Breese/USFWS
Red knots and horseshoe crabs on a Delaware beach. Credit: Gregory Breese/USFWS

Red knots

Red knots are teacup-sized migratory shorebirds that winter in South America. Before returning to their summer habitat in the Arctic, they stop off in Delaware to feed on the eggs of horseshoe crabs to fuel up for the long flight. The crabs’ spawning – prompted by warming water temperatures in the spring – has synchronized with the red knots arrival along Delaware shore beaches. In recent years, however, horseshoe crabs have been spawning later due to extended cold. The crabs are expected to spawn earlier this year due to the mild winter conditions in the region. This is good news for the red knots, which have arrived too early in recent years and missed the “egg buffet.” Biologists expect the red knots to arrive in Delaware during the last three weeks of May, giving them plenty of time to bulk up on crab eggs before migrating to their summer home in the Arctic.

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Snowshoe hare Credit: Jared Withers/NPS
Snowshoe hare Credit: Jared Withers/NPS

Snowshoe hare

The snowshoe hare is known for its dramatic seasonal camouflage, changing from deep brown to snow white in the winter. These hares are so acclimated to the typical four seasons in northern New England that their fur transitions to winter white even if there’s no snow. It’s actually the length of daylight that triggers the hare’s hormones to make the shift to a more cryptic color. A white animal on a snowless landscape has few places to hide making it easier prey for lynx, raptors and other predators.

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Black bear Credit: Mike Bender/USFWS

Black bear

In the weeks before it holes up in its den, a black bear slows down, becomes sleepy and waits for cold temperatures as its cue to hibernate. Unseasonably warm weather can throw off its instinctive behavior. It may delay entering the den, leaving it vulnerable to harm in its lethargic pre-hibernation state. The bear will awaken from hibernation weak and ravenously hungry. Warm weather may cause it to emerge from its dens too early to find a banquet of berries and nuts to satisfy its appetite. This scarcity of food can pose an additional hardship for a mother bear trying to feed her cubs.



Last updated: March 6, 2012