Birds, beavers and other critters can adapt to harsh weather, experts say.

SPRINGFIELD – It was a day for wildlife biologists to envy some of their fur-wrapped research subjects as temperatures barely inched above zero across Massachusetts on Thursday and brisk winds made it feel as if it was well below zero.

“Beavers have got it easy on a day like this,” said Marion Larson, information biologist with the state Division of Fisheries and Wildlife.

While state biologists seized the opportunity provided by the hard freeze to tramp across frozen beaver ponds checking lodges and cleaning out wood duck nest boxes, the beavers stayed in.

“They are having a high time now,” Larson said. “Their work is done. They’ve gathered their winter food supply. The beavers are high and dry in their lodge with a layer of fat and two layers of fur to keep them warm. And a covering of ice over their pond to prevent predators from breaking into their lodge.”

Deer, bear and other native New England animals have evolved with the cold and adapted to it with thick layers of fur and down and other strategies ranging from hibernation to just hunkering down in a protected spot.

Ruffed grouse take advantage of the insulating effects of snow by burrowing into deep drifts. They’ve also adapted to eat the frozen buds on hemlocks and some deciduous trees and in winter sprout scaly spruce-needle like growths on their feet that act as snow shoes.

Even so, a sudden cold spell can have an impact, said Tony Gola, a biologist in the division’s Pittsfield office, where it was 12 below zero on Thursday morning.

“Animals, particularly birds, require some time to acclimate,” he said. “But as long as they have food and can get out of the winds they will be all right.”

Good insulation

Still, in high winds and severe conditions some can succumb. “Feathers are extremely good insulation, but if birds pick a spot that may not be as sheltered, high winds can ruffle their feathers and that dumps out the heat,” he said.

“The big thing about the weather is how it affects the ability of birds to find food and keep their furnace stoked,” said Simon Perkins, field ornithologist for the Massachusetts Audubon Society. Ice storms, rather than severe cold or snow, pose the highest danger, he said.

While putting out bird feeders gives humans a better look at the creatures, and the birds a little extra food on a cold or snowy day, people don’t need to be concerned about birds starving if humans aren’t around to dish out the sunflower seeds.

“We get a lot of calls from people who are worried about going on vacation,” Perkins said. “But feeding birds is not essential.

Studies have shown that even such birds as black-capped chickadees actually spend a small amount of their time at feeding stations indicating that, even if given a choice, they prefer insect eggs and larvae they find in the bark of trees.”

The search for food brings some birds south from the tundra and boreal forests into New England in winter, including rodent-eating snowy owls and seed-eating snow buntings and common redpolls. And sends freshwater ducks moving toward the coast and open water.

On Thursday it wasn’t easy for birds or humans to locate open water.

“It’s much more fun in the summer,” said Major Roger Arduini of the state environmental police, whose coastal patrol boat was mired in the ice on Boston Harbor and waiting for a Coast Guard icebreaker to break it free.

Even some of the hardiest inland sportsmen were taking a bye.

“We’ve noticed a definite decline in the number of ice fishermen today,” Arduini said.