Critical snow depth: how this parameter affects the life of animals in winter (7 photos)

Winter is a rather difficult period in the life of wild animals. Animals have to face a lot of problems. One of them is the depth of the snow cover.





At first glance, snow does not feel like a serious danger. Well, where does it fit in with the blood-freezing cold and critical lack of food, for which you have to prepare as much as six months in advance? However, for a number of species, it is snowy winters that are the factor limiting their range.



It seems that such snowfall causes problems not only for animals

At the beginning of winter, crystallized water does not particularly interfere with life. Yes, moving around becomes a little harder. Yes, it’s easier for predators to find you by following your tracks. But the real problems begin when the snow reaches a critical depth.





Example of critical depth

This is the name given to the height of the snow cover, at which energy costs for movement increase sharply and radically. Well, since more energy is spent, then you need to eat more actively. But to get food, you have to move a lot. Vicious circle!

The critical depth is different for each species and depends on the length of the legs. Even 3 centimeters are enough for voles to get stuck in a snowdrift. Foxes become uncomfortable at 30-40 centimeters, but it is normal for elk to trample through snow up to a meter deep. But if a critical value is reached, then the animals have to change their gait. From normal steps, the animals switch to jumping or even wander as if breaking through a stormy river stream. If you've ever walked in deep snow, then you understand them.



Yes, critical depth is a serious limitation. But where there are restrictions, there are always attempts to get around them! For example, small animals do not try to crawl through the snow, but begin to build tunnels in it. They are easier to move around, warmer and much safer. So the critical depth is critical for rodents only at the beginning of winter, when the snow cover is unsuitable for construction.



This trick will not work for large animals. That's why they resort to physics! Absolutely all northern animals strive to reduce their weight load. This parameter is the ratio between the weight of the animal and the area of the feet/paws/hooves. Simply put: the wider your paw, the less likely you are to fall through the snow.



A snow leopard passed through here. The weight of most of them does not exceed 40 kilos, and their paws are larger than human ones!

Therefore, the hooves of an elk from the forest-steppe zone are narrower than the hooves of its counterpart from the snowy taiga forests. And those who live in the snow constantly turn their paws into full-fledged snowshoes. For example, a reindeer: the toes on the animal’s hooves are mobile. Running through a snowdrift, the animal spreads its toes to the side, which is why it walks through the snow as if on skis!



Well, those who have problems with physics solve the problem collectively! For example, wolves. The line is headed by an individual full of strength. Other members of the pack follow him exactly in his wake. Predators follow each other so clearly that it is often unclear how many wolves are in the group. The animals do this not for conspiracy, but to save energy. It is easier to follow a well-trodden path than to carve out your own. When a leader is exhausted, someone who has already had time to rest takes his place. And so on in a circle until the flock reaches from point A to point B.