Wildlife and native plant species are adapted to surviving bouts of severely cold weather.
But individuals undoubtedly suffer and die during cold snaps like the recent 12-day period when temperatures never got above freezing, experts say.
“An animal that is old or already a little bit injured — the cold is going to take its share of sick or already compromised wildlife,” said New Jersey Audubon’s Scott Barnes, the program director for All Things Birds.
The period from Dec. 27 through Jan. 7 was the fourth-longest streak of temperatures staying below 32 degrees Fahrenheit ever recorded at Atlantic City International Airport, said Press meteorologist Joe Martucci.
For the most part, the lows stayed in single digits and the highs in the 20s, Martucci said. It was the coldest start to a year on record, he said.
Carole Stanko, chief of the state Department of Environmental Protection’s Bureau of Wildlife Management, said wildlife has evolved through millennia to handle temperature swings.
“Even though we’re not used to cold snaps, it doesn’t mean they can’t tolerate them,” she said of wildlife.
She said physical, metabolic and behavioral changes make it possible for animals to survive the winter just fine.
Hibernation and torpor are types of metabolic change used by bats, bears and other animals, she said.
Bears go into torpor, or a state of lethargy and inactivity, rather than the deeper state of hibernation, said Catherine Tredick, assistant professor of environmental science at Stockton University. She has studied black bears extensively.
Physical changes include growing a winter coat with hollow fur, as deer and foxes do, that traps body heat.
“Even birds in snowstorms look bigger and fatter,” Barnes said. “They puff their feathers out and warm pockets of air help keep them warm.”
Another physical change keeps gulls’ feet from freezing, Barnes said.
“They have no feather on their feet. It has to do with circulation,” Barnes. “They can pump a lot of blood through their feet. It’s like a highway of warm veins.”
And behavioral changes include simply hunkering down and staying in the warmest spot they can find for the duration.
“In my backyard there were no footprints for 10 days,” Stanko said. After the severe cold broke, “it looks like a highway again, with squirrel, deer and rabbit prints. It’s back to business as usual.”
The extreme cold can benefit native plants and trees by knocking back the insect pests that feed on them, said Ron Hutchison, associate professor of biology at Stockton.
Plants also use adaptations to survive extreme cold, he said. Many create a kind of “antifreeze” by pumping more sugars to keep ice from forming in their cells.
As long as they aren’t dried out by high winds, they do well, he said.
“It’s the ones we bring in and plant from other places that are a problem,” Hutchison said of non-native landscape plants from more southern climes.
In the animal world, individuals that have strayed further north than the species as a whole are at increased risk, said Barnes.
“Rewards may be higher; there is no competition. But the downside if they have pushed it too far north … they might not reproduce or might themselves be in trouble,” Barnes said.
Tredick said much depends on how much body fat animals have stored going into winter. The longer and deeper the cold weather and snow, the more animals must tap into fat stores.
The recent cold period lasted longer than the famous “polar vortex” of January 2014, when severe cold swept down from far northern Canada and brought two, two-day cold snaps dipping temperatures into single digits, Martucci said.
Fish also migrate to avoid cold, and stragglers can run into trouble, said Stockton University associate professor of marine science Mark Sullivan.
He cited a case of two thresher sharks washing up frozen on Cape Cod beaches.
“Those sharks were apparently migrating to warmer waters to the south and got caught on the way,” said Sullivan. “They are very active animals, with high energetic demands. They might not have been able to meet those in colder water in terms of finding food.”
Atlantic menhaden migrate south during the winter, and fluke and summer flounder move to deeper water further out in the ocean where temperatures aren’t as affected, Sullivan said.
Most should already have migrated, but “any individuals that are late in starting could encounter some issues,” he said.
Since the vast majority of fish are cold-blooded, taking on the temperature of the water around them, some species simply change their metabolic requirements by slowing down, Sullivan said.
In general it’s not a good idea to feed wildlife, but birds are an exception, said Barnes.
“Keep bird feeders stocked. Studies have shown the percentage of time birds spend at feeders is the minority,” he said. “They still spend the majority of their time out naturally feeding. But in a really big cold snap like this, a well stocked bird feeder probably does make a big difference.”