The world’s least-studied penguins only lay two eggs per breeding season and then abandon the first.
Most often, the first egg laid by a mother is the one that dies. erect-crested penguins (Eudyptes spateri() just rolls away. Sometimes the female will deliberately throw out their firstborn and push it out the nest.
This bizarre behavior was first noticed in 1998. Researchers who conducted fieldwork on remote, uninhabited penguin islands are now beginning to understand the phenomenon.
Reanalysis of old data shows that these subantarctic penguins have been forced into indirect and direct infanticide due to inability to find the same amount krill or squid as their ancestors.
Penguin mothers prefer to keep the smaller first egg as the second is larger. There are many theories. However, researchers behind the new study believe that the smaller egg was formed while birds migrate to the breeding islands off New Zealand’s southern coast. The second egg is laid approximately five days after its predecessor.
The egg size differences are not uncommon for all seven species of crested penguins. Other species in which females produce more eggs to ensure egg survival, the first one tends be bigger.
Although the data regarding the erect-crested penguins are obvious, it is several decades old. However, scientists have not yet been able to find any scientific information about these birds, likely due to their remote habitats.
Birds are currently in danger. This is despite the fact that very little is known about them. Researchers Say itThe 1998 study is “still the most complete data available on this species”
It is vital to understand how these birds breed in order to conserve them. If scientists are right, these penguins may be suffering from an evolutionary hangover that no longer proves useful in the modern world – and are doing their best to adapt.
The ‘egg B,’ which has more food for the mother penguins, has some unique advantages over the ‘egg’ that was laid earlier. These penguins will place the larger egg at the back of their brood area when incubating their eggs.
Egg B’s size indicates to the mother that Egg A may be receiving more food, increasing its chances of survival.
About 80 percent of the 113 nests that researchers studied in 1998 revealed that approximately 80 percent of A eggs were lost either before or on egg B’s day. The rest of the eggs were lost within a week.
Over 90% of the times, eggs were simply laid directly on the ground. Sometimes they were squeezed onto a mat made of straw-like dried grass.
The experiment was carried out by researchers at the time, who wanted to see if penguins could be bred in another colony.
The team put a ring made of stones around 14 nests to stop A-eggs escaping.
A-eggs from the manipulated nests died earlier than 28 left unaltered nests. All of the initial eggs in both groups were lost.
However, almost 65 percent were found with broken eggs in the nest when the human-made stone ring was present. The eggs in the unaltered group were found rolled away while others were missing completely, most likely because they had rolled off the plateau on the island where the colony was nesting.
Many birds didn’t bother to incubate eggs A while they were there.
“This is combined with low copulation rates that are an order of magnitude lower than Adelie penguins of comparable size, and low fighting during the courtship phase, points to low reproductive readiness among erect-crested penguins arriving in the colony to breed,” said the authors. ConclusionIn their new paper.
These results are in contradiction to two of the most important hypotheses regarding the penguin penchant for parental rejection.
One suggests that A-eggs die from fighting during the courtship period. However, this is not a true based upon behavior and hormone levels.
Another hypothesis is that the first-born are protected against the loss of the larger second-born.
Researchers believe that this is also unlikely. Discuss. Erect-crested penguins can be derived from ancestors who also laid two eggs. Theoretically, natural selection could work to decrease the clutch size if food becomes scarcer over time. The birds would cease laying another egg.
However, selection seems to favor second eggs for the reasons mentioned before.
“It is physiologically impossible to have another egg without laying the first egg. The best thing crested penguins could do is decrease their investment in the first egg.” These are the explanations of the authors.
“Erect-crested penguins have the highest egg-size dimorphism and do this to an extreme degree.
Researchers found it paradoxical that such an endangered and fascinating penguin species should remain unknown in our day and age. Say it.
It’s also quite shameful.
The study was published by PLOS ONE.
