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Ravenous black bears scurrying through trash cans for dinner, mosquitoes swarming in the early grass, amorous deer behaving like, well, rabbits. Creatures great and small are being thrown for a loop this winter as the unusually warm climate stirs all forms of wildlife from their natural hibernation and reproduction cycles.  

Call it the “Jumanji effect.”

It will cause bat populations to crater and deer herds to double. It had famous groundhog Punxsutawney Phil stirring days or even weeks early, before seeing his shadow at 7:25 a.m. Thursday, Feb. 2 -- meaning "winter" will continue for six more weeks.

But rather than hibernating through freezing snowstorms, nature is being awakened by the weird warmth. Even black bears are likely to rise early from their October to March slumber -- and they’ll be ravenous, said Paul Curtis, a professor of natural resources and wildlife specialist with Cornell University.

“They’ll be hungry when they come out of their dens after hibernating all winter,” Curtis told FoxNews.com. “Their fat reserves will be gone and they’ll be looking for easy food.”

Thanks to a winter that has averaged at least five degrees above normal, according to Art DeGaetano, a climatologist and the director of the NOAA Northeast Regional Climate Center -- above-average temperatures that will continue through April, per the National Weather Service’s long range forecasts -- Black bears could show their faces in the next few weeks.

“By mid- to late February, black bears will be coming out of their dens,” Curtis said. They’ll most likely go after bird feeders and other human-created food sources -- up to 80 percent of the omnivorous species’ diet is plant material, he explained.

But other animals do have a blood lust, and thanks to the warm weather, they may attack like the plague this summer.

“This year, lots and lots of hungry ticks will emerge even on warm winter days,” said Jody Gangloff-Kaufmann, a professor of entomology and a specialist with the New York State Integrated Pest Management Program.

The boom in ticks is partly thanks to a soaring deer population, which will have survived the mild winter in record numbers. And where deer numbers are up, so are ticks.

Other blood-thirsty pests will make the summer of 2012 one for the record books as well, again thanks to the odd weather. The extreme cold snaps typical in many U.S. states have yet to surface -- weather that typically kills a good portion of the dormant mosquito population.

“I anticipate the mosquito problems we normally see to be much more intense and begin earlier than usual if the weather continues to be mild,” Gangloff-Kaufmann said. “Even the fleas have had a boost so far this winter and many people are complaining about flea problems right now, in the middle of winter.”

Still another climate-related factor will cause mosquito swarms to inflate: a serious dip in bats. Mosquito-munching bats have been dying off, due to a fungus that has decimated the population.

“We may have lost five and a half to six and a half million bats in eastern North America in the last five years,” Curtis said. The fungus may be causing them to wake early, itching and hungry. And when they emerge unexpectedly in January or February looking to feed, they starve to death.

Will anything save us from the coming mosquito onslaught? Ironically, a lack of precipitation may be our savior as the summer nears.

“Mosquitoes need standing water for breeding,” Curtis told FoxNews.com. April showers bring May flowers, but they also bring swarms of mosquitoes in June, July and August. If we have early spring storms and wet weather, Curtis warned, watch out. But a dry spring may cut down on the swarms.

For the time being, Curtis is more concerned with the bears. Scientists typically take advantage of the snows and cold to study hibernating bears in February.

“Usually, there’s snow on the ground, making February an ideal time for studying them,” he said.

"If we’re going to do winter den work, we have to do it early in the year."