If you’re a wildlife biologist, you probably want to know everything there is to know about species of animals you are interested in. You are also probably not reading this blog post. For the rest of us, we might settle to learn the ‘Cliffs Notes’….at least at first. Lucky for you, you can understand more than most people about a particular type of animal by learning three things:
- How does the animal survive winter?
- How does the animal avoid predators?
- How does the animal reproduce?
Animals are usually simpler than human beings. They don’t have career dreams, hopes for adventure, a desire to travel, or a lust for material possessions. They mostly just survive, reproduce, and have a little fun along the way.
Recently, I was talking to someone who incorrectly thought ruffed grouse mate in January. Of course, they mate in May. However, understanding why ruffed grouse and most other animals don’t mate in mid winter is a wonderful application of our new found approach.
As humans, we came to be in a warm climate and now live in heated homes. But it’s pretty intuitive even for us to understand why mating in mid winter is undesirable. Sure, plenty of children are conceived in ski resorts and on New Year’s Eve. But wild animals don’t have cozy cottages to spend the evening. I doubt a lot of human copulation occurs behind a tree on the ski slope in 0 degree weather. The exception might be teenagers.
When we are in freezing cold weather, even we humans feel the pull of biology to conserve energy and consume more calories. In the winter, most warm blooded animals use more calories to stay warm and find food as food is generally also more rare. They become more idle and focus only on necessary activities. Mating takes a lot of energy, especially for males. This energy isn’t just used in the act, but especially in the pursuit of mates.
Ruffed grouse are rare among plant eating animals in that they have plenty of food in the winter. They fly up to the top of trees and use their strong beaks to break of young buds and branch tips from trees. Since grouse live in the forest and can fly to the top of any tree, they don’t starve. Nonetheless, this activity and the lack of leaves makes them vulnerable to predators such as hawks and owls.
But birds and mammals differ greatly in their reproduction habits. While most animals don’t mate in the winter, many mammals carry the fetus of their young from fall to spring. While the males may exert more energy in mating, they typically take the left of the stage immediately thereafter. Since, mammal females carry their developing young inside their bodies, they keep them plenty warm assuming she, herself, survives. Birds are also warm blooded, but they incubate their young in eggs outside the body. Keeping eggs warm in a snow bank is no easy task.
These eggs are laid some short time after mating and incubation typically takes less than a month. And that’s important because if birds mate in mid winter, then they also end up with hatched chicks in mid winter. The only animal I know off hand that births their young in mid winter is bears. Bears have their young during hibernation and nurse them in the den. Bears make this rare choice probably because it wouldn’t work any other way. Their single chambered stomachs can’t achieve as much energy from late spring and summer grass and weeds like other animals, so nursing at this time would be difficult. They couldn’t have their young in the fall because then the cubs would be unprepared for hibernation themselves.
Nonetheless, the important aspect that allows bears to do this is that they produce milk and nurse. Otherwise, the only other option would be to horde food in the den. Birds, however, do not produce milk or nurse their young. They must either gather food and feed them or teach them to find food themselves. Anyone who has ever raised poultry knows that they should buy high protein food for growing chicks. In the wild, many young birds achieve this protein by eating insects. Insects are cold blooded and exceptionally rare in mid winter.
Thinking about what I just said, I was pondering to think how silly it would be to believe that any bird would mate in the winter in Michigan. But a quick google search showed I was in fact wrong and great horned owls mate in the winter. The other animal I’m aware of doing this are coyotes. It’s probably not a coincidence that both these animals eat primarily meat. Meat is in much higher supply during the winter than green plant matter. While it’s true that many prey species are hibernating and others will reduce their movements, at least they are still about and the lack of leaves, deep snow, and need to secure easy food make many animals vulnerable to predators.
So from these scattered examples, we now have the tools to understand most animals. This is a much better approach than memorizing random facts as it provides a way to understand the why and how that animal behave the way they too. But also prepare to be surprised, by owls.