Do animals go through break-ups? What the science reveals

Matthew E Wolak, PhD., Department of Biological Sciences, Auburn University, tells IE that many animals form “persistent, cooperative relationships that often serve to provide mutual care of dependent offspring”.

“However”, he adds, “these relationships can and do often end such that the individuals go on to form relationships with new individuals.”

He says that researchers of the subject of animal break-ups have focused a lot on birds, since about 80 percent of species are classified as socially monogamous. What is meant by that in this instance is that females and males pair up to do various reproductive activities such as building nests, defending territories, incubating eggs, and/or feeding chicks. These pairs can last for either a single reproductive event or a lifetime, “but among birds divorce is commonly observed”, says Wolak.

When ornithologists refer to “divorce,” they mean that both members of a breeding pair survive to the following breeding season but find new partners as opposed to reuniting.

Wolak adds: “Explaining the rate of occurrence of divorce and the extent of among-individual variability in the tendency to divorce is a major field of research in ecology and evolutionary biology. In my own research, my collaborators and I have investigated whether there is any repeatable pattern of individuals breaking up with their social mate to form a pair with a new individual.”

So, do some individuals divorce their partners more often?

Wolak says: “From intensive study of a population of song sparrows over a 40-year period, we found an average 12 percent of pairs ended in divorce. Also, although the behavior of divorce varied among individuals, the variability was mostly explained by extrinsic factors of individuals and so we did not see much evidence to support the idea that some individuals did or did not divorce their partners consistently.”

He adds that researchers are now investigating why certain pairs end in divorce and others do not, “and we’re trying to figure out what is it about the environment or the partner that might lead an individual to switch partners.”

Something of a work in progress then…

Why it happens

Josh A Firth, a zoologist at the University of Oxford, says a recent analysis into the subject managed to rule out a number of possible causes of avian divorce, including low reproductive success rates, infidelity, and genetic or behavioral compatibility. He says: “In wild animal populations, divorce can be driven by consequential effects – almost accidentally.”

“But” Firth adds, “there is often some incidence of divorce between pairs, and divorce rates differ massively between species/populations, with some species having less than five percent divorce rate while others have very high (almost 90 percent) divorce rates.

“Interestingly, there is also a body of evidence that divorce in birds can hold negative consequences, such as reduced survival or reduced reproductive opportunities.”

The study Firth is referring to was conducted by behavioral ecologist Carol Gilsenan of the Max Planck Institute for Ornithology in Germany. Her team monitored hundreds of Eurasian blue tits for eight years, using artificial nest boxes in a protected forest in southern Germany.

In their findings, published in Animal Behaviour, “64 percent of breeding pairs split up during the study, even though faithful pairs produced more eggs and reared more fledglings. If both members of a pair returned to their previous territory around the same time, they were more likely to reunite; if they were on different schedules, they were more likely to separate.”

It’s an animal thing

This phenomenon isn’t confined to birds, according to Kerianne Wilson, PhD, NSF Postdoctoral Fellow, Evolution, Ecology and Organismal Biology, University of California, but she says a lot of what we know about divorce in animals comes from our research into birds.

Wilson says: “Animals of species that pair monogamously do sever their pair bonds and find new mates. But since upwards of 80 percent of bird species are monogamous, much of what we know about divorce in animals comes from studying birds.”

As to what proof there is for this, she adds: “Divorce has been observed in wild populations and/or laboratory populations of monogamous species of birds including zebra finches, great tits and barn owls to name just a few.

“Divorce can occur within a single breeding season when a pair separates during a breeding attempt. Divorce can also occur between breeding seasons when birds fail to return to their same mate from the previous breeding season. Many studies have also looked at the causes and implications of divorce in monogamous species of birds, including zebra finches, great tits and barn owls, to name just a few.”

Nothing breaks like a heart… or does it?

While humans break-ups can be hugely painful, can the same be said of animals? IE put this to Wilson, who says she isn’t aware of any studies that have looked at the neural or emotional implications of divorce in animals, “but I do hope we know the answer to these questions someday”.

And as to what she’d say to someone who says the idea of animal break-ups is nothing more than anthropomorphization, she says: “Whether you are more comfortable describing the behavior in animals as mate switching, pair bond disolution or divorce, it is all describing the same set of natural observations.”

So, in straightforward terms, yes, animals do break up – sometimes because it’s the most sensible thing to do for survival, and sometimes simply because it just doesn’t suit them anymore. Maybe we could learn a thing or two from the animal kingdom.