As the deep freeze deepens in the days ahead, Iowa wildlife will suffer additional winter stress, but most should survive as long as ice or mounting snow does not cut off their food supply, state officials say.
Extreme cold per se — such as the 72-hour subzero stretch predicted to start Sunday – is not in itself especially harmful to wildlife, according to Department of Natural Resources biologists.
“If they have good winter cover next to a good food source, three days of extreme cold won’t matter,” said Jim Jansen, the DNR’s northeast Iowa wildlife supervisor.
Outbreaks of arctic air underscore the importance of shrubs, conifers, cattails and other thick vegetation that can provide cover for wildlife when snow obliterates grassy habitat, Jansen said.
From Jansen’s perspective in northeast Iowa, it’s already been a hard winter, with above-normal snowfall and below-normal temperatures.
“If the snow keeps piling up, we could see some deer mortality, especially among fawns and young bucks,” he said.
Pheasants, perhaps the most vulnerable of the state’s game species to severe winter weather, seldom freeze to death, said DNR upland game biologist Todd Bogenschutz.
Scientific studies, he said, show little correlation between winter temperatures and pheasant mortality.
A much better indicator, he said, is the number of days snow covers the pheasants’ habitat.
Heavy snow buries much of the vegetation pheasants and other small game animals depend on to protect them from the elements and from predators, Bogenschutz said.
The longer they have to live against a white background, the more vulnerable to predators they become, he said.
Heavy snow and ice, which prevailed in the bitter winter of 2000-2001, can also limit wildlife’s access to waste grain, a key component of their winter diet, said Todd Gosselink, a DNR research biologist and turkey expert.
As long as the snow stays light and fluffy, turkeys and pheasants can find food in windswept grain fields, but deep, wet snow or a layer of ice can be a limiting factor, he said.
While feeding songbirds is highly recommended, most DNR biologists caution against scattering grain for pheasants and turkey for fear that it will concentrate them in areas where they will be vulnerable to predators and make them dependent upon the food source.
“Good food plots in good cover – that’s the way to feed pheasants,” Bogenschutz said.
Well adapted canine predators like foxes and coyotes “are the least of our worries in cold weather,” said DNR furbearer specialist Vince Evelsizer.
“They’ll just hunker down out of the wind in thick cover and come out hungry when the weather breaks,” he said.
Bitter winters mean little to true hibernators like woodchucks and partial hibernators like raccoons, skunks and opossums, which live off fat reserves during cold spells, Evelsizer said.