For many of us, winter means changing our wardrobes, cranking up the heat and cutting back on outdoor activities. For forest wildlife, especially in the north, no season has a greater impact than winter. Those animals that can’t flee south must kick into deep-freeze survival mode or perish.
Some small insects such as orb weaver spiders, mantises and most butterflies die with the first frosts. But they leave freeze-resistant progeny as their legacy. In the case of butterflies, that usually means larvae (caterpillars) or pupae in their protective “wrappers.” But some butterflies, including the mourning cloak, hibernate in a sheltering crag or crack. Unlike orb weavers, other types of spiders hibernate beneath rocks or under tree bark, where wandering flocks of watchful chickadees, nuthatches and brown creepers may find them.
Toads and terrestrial frogs such as peepers try to dig or shelter in places that protect them from hard freezes, including cracks in logs or thick leaf litter. But even a hard freeze usually will not kill a temperate-area frog. Breathing and heartbeats may stop, but with a thaw, thanks to elevated blood glucose, the frogs come “back” to life. Turtles often dig down into the mud, and their metabolisms slow to a crawl.
Even birds that we assume are always warm and active have coldweather adaptations. Chickadees, for example—the most common small songbirds wintering in northern woods—may enter a “regulated hypothermia” while they sleep, their body temperatures dipping to conserve precious energy.
Chipmunks will hibernate but emerge during warm spells, while the restless red squirrel changes its schedule from early to late morning, even tunneling through snow to transport snipped conifer cones to its bulk storage area, known as a midden.
This time of year, some of the best things you can do for wildlife are simple—often involving doing nothing at all. Here are some tips:
• Leave dead meadow stalks standing until later winter thaws come. Meadow plants shelter, among other things, butterfly caterpillars and pupae and mantis egg cases. From fall into winter, their seedheads nourish overwintering songbirds, gamebirds and rodents that in turn feed foxes, owls, hawks and other creatures.
• Hold off on clearing logs, if possible. Logs and snags (dead trees) are always important components of a diversified wildlife habitat, and the shelter they provide during winter is crucial. If you remove this resource during cold weather, you might harm hibernating wildlife.
• Leave dense conifer stands to provide cover for owls, rabbits, grouse and other hardy active critters while other cover is sparse.
• Keep bird feeders topped up. This will provide you with hours of entertainment, and you also will be helping supplement birds’ diets at the toughest time of year. If you want to feed a wide variety of birds, offer not only mixed seeds but also black oil sunflower, thistle and suet. Raisins and mealworms may bring in bluebirds, thrashers and mockingbirds. Also, you could buy a birdbath or pond heater to provide water during the coldest days.
• Hold off on cleaning up nestboxes, as these will provide shelter for birds, rodents and invertebrates during cold weather. Then, in late winter (early March in many areas), clean the boxes out just before bluebirds and other cavity nesters start seeking nest sites.
• Leave brushpiles, which provide dense shelter that can be hard to come by in winter. Wrens, rabbits, sparrows and other creatures seek these out. Bigger brush piles may shelter quail and pheasants at the field-forest edge.
• Refrain from removing leaf litter. Thick leaf litter is like a thermal blanket for hibernating salamanders, frogs and invertebrates— especially when piled around stumps and logs.
Sometimes it feels like winter will never end. But before you know it, frog calls, bird songs and the buzzing and chirping of insects will once again fill the air. For now, though, you can find comfort knowing your forest provides safe havens for a variety of resting wildlife.
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