Several bird species are monogamous, but few of them put on a show of affection like the wandering albatross (Diomedea exulans). They find each other every season after wandering thousands of miles, launching into a tightly synchronized and gregarious reunion ritual. It’s one of the most spectacular couple behaviors in nature.
But this doesn’t tell the whole story.
Previous research found that up to 24% of wandering albatross chicks are reared by a male who is not their genetic father. Penguins, another monogamous species, have an even higher rate (31%). In a new study, researchers found that a significant part of albatrosses get divorced. In this process, personality plays a role, but humans also do.
The love lives of birds
The fact that albatrosses (or other birds) get divorced is not a new finding. Sometimes, birds try to find a better mate, but this didn’t seem to be the case for wandering albatrosses born on the remote Indian Ocean Crozet Archipelago.
When these albatrosses got divorced, it didn’t really seem to help them in any way. They didn’t rear more young, they didn’t seem to favor fitter mates. So, what was going on?
Since 1959, scientists have tracked these birds’ lives in meticulous detail. They noted who mates with whom, who returns to the colony, and who raises chicks. In 2008, they began recording another detail: how bold or shy each bird was during nesting.
Assessing albatross personality is not the easiest task. Researchers did this in two ways. The first is called the “human approach,” and it just involves a person walking towards a bird incubating an egg and observing how the bird reacts. Males and females share incubation duties, so this works for both sexes.
For the other ways, researchers employed the help of Betsy the space hopper cow. Betsy was essentially a cow plushie with a tiny wide-angle camera mounted on its horns to capture how albatross reactions reacted to an object they’d never seen before. Unfortunately, Betsy became a target for a particularly aggressive albatross and didn’t survive the attack.
The albatross reactions in both instances were scored 0-4, with 0 indicating shyness and 4 indicating boldness. Ultimately, researchers found that shy albatrosses were substantially more likely to get divorced.
Personality, risk, and fishing
Why would personality affect pair bonds in seabirds? The researchers suggest that shy males are more likely to avoid conflict.
Decades of female albatrosses being accidentally caught in fishing gear have led to a skewed sex ratio, with significantly more males than females available for breeding. This imbalance fuels intense competition among males for partners. Basically, unpaired albatrosses may be aggressively looking to woo paired females. Bolder males, being generally more aggressive and less risk-averse, might be more likely to actively defend their mate and territory against such intrusions.
Meanwhile, shyer males were more likely to avoid conflict and aggression.
This avoidance might make them more vulnerable to being ousted by a persistent competitor, effectively forcing a divorce. For females, personality appears less critical in this context. With males aplenty, they likely have easier access to mating opportunities regardless of their boldness score.
Researchers have another hypothesis: perhaps shyer males, adopting a more conservative life strategy, skip breeding seasons more often or arrive late to the colony, leading to relationship breakdown due to asynchrony. While possible, the authors deem this less likely to cause permanent divorce, given the birds’ long courtship period and observations of temporary pair-switching when one partner skips breeding. Furthermore, divorce doesn’t seem to boost breeding success here, and males face a long wait to re-pair, suggesting splitting isn’t an adaptive strategy in this population.
This could matter a lot
What does this mean long-term? Well, personality could be under pressure from human interference.
Boldness might not be an evolutionary advantage in a balanced ecosystem. But with humans skewing the odds — by killing more females through bycatch — it might become a favored trait. That’s not natural selection. It’s us, unintentionally reshaping the evolutionary path of a species through industrial fishing.
“By shaping pair-bond dynamics, personality traits may undergo selective pressures,” the authors write. Boldness, in this case, isn’t just a personality quirk — it could be an adaptive trait.
And while we don’t yet know whether this applies to other animals — or even humans — it does add an intriguing twist to the age-old question: why do couples break up?
The study was published in Biology Letters.
