For red squirrel moms, it makes sense to take a chance

About the episode

Suppose you are told the winning numbers of a lottery, but you don’t know which month of the year the jackpot will fall. Playing every month (with the same combination of numbers) of course costs money, but in this case the prize is big enough to do it anyway.

Female North American red squirrels seem to do something similar when estimating how much food there will be for their offspring. From an evolutionary perspective, it is beneficial to have a large nest during a time when plenty of food is available. The chance of the young surviving and being healthy is then – logically – the greatest.

Yukon white spruce trees in Canada produce extra seed once every four to seven years. Think of it as the jackpot. A female squirrel only lives an average of 3.5 years. Assuming she does small litters just to be on the safe side because it’s not certain when there will be such a spike in food security, she’ll probably stay a bit healthier and the few young she does will survive rather than raise huge litters.

But researchers have seen — in more than 30 years of data — that some women take the risk. They make a big nest every time, so when the jackpot hits, their genes are passed on to a large number of young. It’s a gamble, but when they succeed, they do very well.

Well, some squirrels seem to have a better idea of ​​when the jackpot hits. Presumably, they receive signals from trees, but this has not yet been sufficiently studied. Researchers warn that these signals are becoming less reliable due to climate change and that may be bad news for Yukon red squirrels.

Read more about research here: Squirrels Who Play Win Big in Scalable Fitness.