How climate change is forcing animals that mate for life to break up

THEY seemed the perfect couple. Growing up in the same neck of the woods, they went their separate ways in adolescence, before reuniting and hitting it off. But after many years together, they seemed to just drift apart. Divorce soon followed.

This sad story may be all too familiar to many, but there is one important difference. The parties in this case aren’t human. They are birds.

For years now, behavioural biologists have been aware that some animals – birds in particular – choose to pair up for years on end, often raising offspring together. Some researchers have also become fascinated by the fact that these couples can break up. Although scientists are generally loath to anthropomorphise, there are times when even they can’t resist. This explains why the biological literature is full of studies analysing the factors that drive animal “divorce” in all manner of species, from albatrosses to penguins, beavers to seahorses.

Recently, as we have learned more about this, a surprising conclusion has emerged: under the right circumstances, animal divorce can be so beneficial that it might be an evolved trait. But on the flip side, we have also come to realise that divorce rates have the potential to spiral out of control so that viable breeding colonies may decline, dwindle and disappear. What’s more, research has even identified a worrying new factor that might unexpectedly contribute to a sharp rise in this sort of divorce-driven crisis: climate change.