When It's This Cold, Wildlife Species Have Three Options

Jan 28, 2019

How are you coping with the cold weather this winter?

Wildlife species generally have three options as the Masked Biologist notes in this week’s Wildlife Matters.

During our recent bitter cold snap, I spent some time outdoors trying to get work done. Afterward, I came in the house to thaw out, taking off my boots, insulated coveralls, waterproof parka, hat, scarf, and gloves. It occurred to me that very little of my body was exposed and forced to deal with the conditions—basically my eyes. Humans have the luxury of bringing their environment with them, for the most part. Our homes and vehicles are heated. We have many options for keeping our body heat, from special underwear and socks to puffy thermal ring coats and rechargeable electric boots.  Animals on the other hand are not quite so lucky. Wildlife species have three options when it comes to dealing with climactic extremes: migration, hibernation, or mitigation. As with any major life decision, they come with benefits and detractions that make them simultaneously beneficial and dangerous.

Migration is a highly visible adaptation to seasonal weather changes. Birds are a great example; we have some 420 plus species of birds, many of which migrate to Central or South America. They fly long distances in all kinds of weather conditions, some even crossing the Gulf of Mexico non-stop! Once they arrive at their winter destination, the birds are only there for a couple of months to feed up and rest before they head back north to their breeding and nesting grounds. Other animals migrate between summer and winter ranges as well, but nothing as spectacular or dramatic as bird migrations. Well, that is a generalization—here in North America, we do not see huge mammal migrations, but that might be due to the dramatic change we have brought to the landscape. In Africa, wildebeest undertake remarkable migrations. Here, we have some movement of our hooved mammals like caribou, buffalo, elk and mule deer but it is nothing like those on the savannah. Migration has the benefit of safer weather conditions at the winter site, but the journey is a perilous one; risks include predators, weather events, wind towers and guy wires. On arrival they have to deal with significant competition from other species, risk of predation, and the effects of expanding human populations. Deforestation, use of pesticides, and unregulated hunting all take their toll.

Hibernation is an interesting adaptation that allows animals to avoid migration while still minimizing the negative effects of the cold winter weather. Animals live off their stored fat, lowering their metabolic rate and body temperature to keep their energy needs to a minimum. Bears are best known for hibernation, although other creatures like frogs, turtles, and groundhogs also hibernate. They reduce the hazards of long-distance travel and leaving their territory, but they risk failing to eat enough in the growing season to survive the winter. They also risk freezing to death, and (with the possible exception of bears) death by predators.

The final adaptation, Mitigation is about developing special ways to deal with the winter conditions to increase chances of survival. Ruffed grouse grow special combs or pectinations on their toes to help them walk on top of the snow. They also snow roost, diving into the snow and packing down a little fort to sit out a storm or old event. Some animals and birds grow extra fur or feathers to insulate them in the cold, or change their diet due to change energy demands or lack of green forage. Mitigation is a high risk, high reward approach. Animals are highly vulnerable to predation, cold, and disease. Those that survive are well-equipped for survival, first on the breeding grounds and well-equipped to secure the best summer habitat for themselves.

Migration, hibernation, and mitigation are crucial to wildlife survival. Even humans like us have a need to survive winter. Snowbirds flock to the south this time of year. The others of us stick it out, either by working to deal with winter or staying indoors. I don’t know anyone who hibernates, we are not well equipped for it, so the rest of us work to deal with winter on its own terms and take what comes. Striving to make new things familiar and familiar things new, this is the Masked Biologist coming to you from the heart of Wisconsin’s great Northwoods.

The photo above belongs to the WI DNR and can be found on their Flickr page here.