Discoveries

July 14, 2023

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Most bird species are monogamous and have a single mate for at least one breeding season or longer.

But just like humans, sometimes long-term partnerships don’t work out and end up in “divorce.”

Now, an international research team unveiled that the main factors that lead to these breakups are not so different from those affecting human couples, the Guardian reported.

For their paper, they analyzed data regarding the divorce rates of 232 avian species, and included mortality and migration distances as potential contributory factors. The researchers also studied promiscuous behavior in males and females of each species.

Their findings showed that long-distance migrations and male promiscuity play integral roles in higher divorce rates.

The team explained that males become philanderers when they have more opportunities to do so. Consequently, this behavior displayed a reduction of commitment and made a male bird “less attractive as a partner, and thus more likely to be ‘divorced’ in the next breeding season.”

While this is advantageous for males to spread their genes, it wasn’t helpful for females because the expensive cost of egg production means females prefer quality mates over quantity, according to Science Magazine.

Meanwhile, long-distance migration led to more couples splitting because it narrowed the window for breeding. If pairs arrived at a destination in different periods – or at the wrong breeding sites – it would lead one partner to mate with another bird.

The authors also observed that mortality rates and migration distance were related to male promiscuity, suggesting potential indirect effects on divorce.

The study indicates that avian divorce might not solely be a tactic to enhance an individual’s overall well-being or a reaction to environmental circumstances like migration.

Rather, it could potentially be influenced by a combination of both factors simultaneously.

This story originally appeared in the July 14, 2023 newsletter, Ubiquitous Aggression and Violence.