What happens to the animals in winter?

Question

I recognize that there are a few discussions on here already about how humans can properly survive a multi-year winter on Planetos, but I've not yet seen one about the animals. Note that my question is totally notwithstanding the possible conversion of animals into wight-imals.

Specifically, thinking of the fact that even animals in our world end up often hibernating for a few months during the worst of the winter, and all the animals able to be active in the winter are specially adapted for doing so, I'm wondering how it is that common animals such as deer and birds which are not adapted for polar conditions can find enough food and warmth to get through multiple years of winter (especially the ones that last a decade or more).

Carnivores would probably have it good for a while, but I don't see herbivores lasting long without ample plant life, and carnivores won't last long without herbivores.

I've read the whole series several times, and am aware of no real discussion of how wild animals manage. Perhaps something in a world book or interview? I'd prefer a book answer, but if this was mentioned in the TV show then I suppose that would be interesting as well.

Answer 1

Animals likely mirgate or starve and die, much like the humans do.

[Writer] But quite a lot of people are living there. What do they eat?

[GRRM] A lot of food is stored. Smoked, salted, packed away in granaries, and so on. The populations along the coast depend on fishing a great deal, and even inland, there is ice fishing on the rivers and on Long Lake. And some of the great lords try and maintain greenhouses to provide for their own castles... the "glass gardens" of Winterfell are referred to several times.

But the short answer is... if the winter lasts too long, the food runs out... and then people move south, or starve...

[Writer] Are there some areas without snow, which are suitable for agriculture, or are there significant temperature changes inside the "bigger seasons"? To grow a harvest, at least a couple of months' time of warm temperature (15-20 degrees by Celsius) is needed. Is it available in the North?

[GRRM] Sometimes. It is not something that can be relied on, given the random nature of the seasons, but there are "false springs" and "spirit summers." The maesters try and monitor temperature grand closely, to advise on when to plant and when to harvest and how much food to store.

[Writer] And what happens when a winter comes - five, six years long?

[GRRM] Famine happens. The north is cruel.

So we see that during the long winters that people must move south to survive or starve. This would be because the animals (the food source) has done the same. If the animals were able to survive the long winters, it would make it easier for the people who lived there as a supply of food would be more readily available.

Answer 2

The same as what happens to animals in our winters they migrate, hibernate, evolve or die.

However, we can speculate that animals must be able to survive north of the Wall where it is snowy and cold as the wildlings and Craster and his wives lived up there and so there must be food to catch, this is backed up with the following quote:

Mance nodded, and walked away, Harma and Sixskins beside him. Varamyr's wolves and shadowcat followed behind. Jon and Ygritte were left with Jarl, Rattleshirt, and the Magnar. The two older wildlings looked at Jon with ill-concealed rancor as Jarl said, "You heard, we ride at daybreak. Bring all the food you can, there'll be no time to hunt. And have your face seen to, crow. You look a bloody mess."
_{A Storm of Swords, Jon II}

We also know that as of Season 7 Episode 6, "Beyond the Wall", other animals such as bears used to live beyond the Wall.

If animals are able to live this way all the time it makes sense that other animals will be able to do the same.

Note that there have also been other winters and animals have been around afterwards for food so we know they can survive.