It was only now possible to explain the mysterious behavior of birds.
Straight-crested penguins, one of the least studied in the world , lay two eggs during the breeding season. But they drop one of them. Most often, the first egg is simply rolled, but in some cases the female deliberately pushes it out of the nest, reports Science alert.
This strange behavior was first noticed in 1998. And only now scientists, who conducted field observations on remote islands, think they have figured out what is the matter.
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The researchers re-analyzed the old data and concluded that the birds are forced to resort to infanticide because they cannot find as many krill and squid as their ancestors. Scientists note that over the past 50 years, the number of penguins has decreased.
The first egg laid by penguins is much smaller than the second, so mothers prefer to keep the last one. There are several explanations for this, but the authors of the paper believe that the whole thing is that the first egg begins to form while the penguins are still migrating to the nesting site. The second egg is laid five days after the first.
Scientists have known about the existence of straight-crested penguins for decades. But the data on them is quite scarce. Probably, due to the fact that these birds live in rather remote regions. Currently, these penguins are under threat of extinction. Scientists say the 1998 study is the most complete set of data on penguins.
Understanding how the birds reproduce is key to saving the species. If the scientists' guesses are correct, these birds are doing everything possible to adapt to the new realities of existence.
Because more food is available to the female penguin, “egg B” has a number of features that give it advantages over “egg A”. It is larger, that is, the penguin has more chances to survive.
In 1998, scientists studied 113 penguin nests. In 80% of cases, “egg A” was left on the day of laying “egg B”. In other cases, it took a week. In 90% of cases, eggs were laid simply on the ground, in others they were laid on something resembling a straw mat.
Scientists conducted an experiment with penguins that nested nearby. They placed a ring of stones around the nests, which prevented the “eggs A” from rolling. In other nests, all “eggs A” were lost, in those where a ring was created, they were broken. Many females did not even consider it necessary to incubate “egg A” while it was still in the nest.
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According to the researchers, the refusal of the first egg can be explained precisely by the need for selection. It is impossible to get a large second egg without the first, so the most correct strategy in this case is to reject the “firstborn”.
