There is something cute—maybe even romantic—about penguin courtship. After spending months at sea, looking for fish and swimming in the icy waters, female Adélie penguins (Pygoscelis adelia) skate in the same breeding grounds, year after year. Wandering through the bar scene of swarming males, they shrug off progress and make a bee streak for their mates from the previous season: the males who arrived before the females to arrange their nest.
Penguins like these are models of long-term commitment. But are all penguins bound to one partner for their entire lives?
It turns out that these penguins may be the exception rather than the rule. Although most penguins mate with only one partner per breeding season, they may mate with several other penguins in the breeding colony before settling in the nest. Fidelity rates vary greatly across species. Penguin love – it’s complicated.
“The short answer is no, penguins aren’t really monogamous,” said Emma Marks, a behavioral ecologist at the University of Auckland in New Zealand who studies breeding behavior and mate selection in colonial breeding species. . “Colonial breeders may be like penguins are monogamous, meaning they have one mate that they nest with and raise chicks each season,” Marks told Live Science. But this does not mean that there are no ‘extracurricular activities’.
It is safe to say that penguins are not monogamous. Many of the penguins play on the field before they hang out with their mate for the season — sometimes mating with other members of the colony they’ve already spoken to, causing a drama of operatic proportions, according to Marks.
When a male associated with a pair of men fails to return to the breeding grounds, for example, his single mate may approach a different male. When the obedient partner of this male from last season arrives at the nest only to find a new female in her place, a fight ensues. Usually the original female wins.
One consequence of these chaotic love triangles is that by the time the female lays her egg, it is not always clear whether the male you will spend the season with is raising his chick. 2018 study in the journal zoo biology (Opens in a new tab) Description of one Gentoo penguin (Papua Pygocilis) in an aquarium in Utah, who ended up raising two chicks of different male offspring, through the mixing of his related mate. The study authors said scientists aren’t sure how often this occurs in nature because while tracking devices and other technologies can help researchers monitor mating behavior and bonding between pairs, there have been no concerted efforts to test the paternity of chicks in the wild.
At the same time, penguins are somewhat monogamous socially. It takes two committed partners to raise a chick in a harsh environment like Antarctica, and a penguin pair bond to efficiently divide the responsibilities of nest maintenance, egg incubation and hunting.
Marx said, “Social monogamy is a prerequisite.” “Rearing chicks requires a lot of coordination between the two, and if that is disrupted, the breeding will be a failure for the season.”
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These social arrangements can last over the long term, with each breeding season returning the same penguin parents to their nest for another year. How often this happens depends in part on the species. 2013 literature review, published in the journal Biology Reports (Opens in a new tab)found that 89% of penguins in the Galapagos Islands (Spheniscus the beggar) stick to their mates; However, in a 1999 study in the journal auk (Opens in a new tab) It was found that only 15% of emperor penguins (Aptenodytes foresteri) Look for the same partner in subsequent breeding seasons. Most species return to the same partners at least fairly consistently, with accuracy rates between 59% and 89%, according to a 2013 study.
Marks explained that the success of the previous season also plays a role in determining whether or not the penguin pairs will stay together for the long term. If the pair manages to raise chicks to maturity, and the male keeps a high-quality nest in a well-placed location, the odds of the female returning to her former partner are generally higher. Otherwise, females are more likely to wander in search of greener pastures.
“For colonial species, there are a lot of options,” Marks said. “If the mating process has previously failed, we generally expect to see more ‘divorce’ cases in the next season.”
It’s hard to calculate true rates of “divorce”—penguins actively discard former mates in favor of new conquests—because not every penguin returns to breeding grounds every season. When new pairings occur, it can be difficult to determine whether it is personal, or whether the penguin has moved after the other half failed to return – for example if it was eaten by an orca or seal.
Predation is not the only threat to the penguins’ love life. A recent study published in the journal I’m walking around (Opens in a new tab) It found that penguins numbers were declining in proportion to the decreases in the amount of krill available for feeding. According to the study, climate change and human hunting activities are the main factors responsible for the decline in the krill population. Climate-induced shifts in sea ice also force penguins to live in different breeding grounds, break up long-term pairs and affect migration. Some males now reach their breeding grounds exhausted from navigating the changing landscapes of sea and ice, Marks said, are too uninterested in attracting females and spend too much to properly care for eggs.
Collectively, these factors are believed to have played a role in Widely reported failures (Opens in a new tab) from Haley Bay. The breeding site that has hosted 25,000 pairs of emperor penguins each has been a barren season since 2016.
“It is likely that climate change will reduce the success rates of colony reproduction,” Marks said. “When there are higher failure rates, we expect higher rates of partner turnover.”
Originally published on Live Science.