Bird eggs change color depending on how WARM their nest is on animals in colder environments that lay darker animals to absorb more heat, reveals research
- Birds lay eggs with different colors and patterns, but it was not understood why
- Researchers mapped the color of eggs from 643 different bird species
- They found birds that lay eggs in colder climates and used darker pigments
- Dark eggs absorb more heat from sunlight to keep them at the right temperature
Birds that lay their eggs in open nests and in a colder climate usually have darker egg shells than those with more enclosed nests or warmer habitats, a study finds.
The dark pigmentation helps the eggs absorb more heat from the sun and maintain their intended incubation temperature for longer, according to American researchers.
The findings can help explain the variation in coloring and patterning of bird eggs, the cause of which was previously unclear.
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A study finds that birds that lay their eggs in open nests and in a colder climate have darker eggshells than those with more enclosed nests or warmer habitats (stock image)
WHAT ARE EGG SHELLS MADE OF?
Eggshell is formed from calcium carbonate and special proteins that give it strength.
In a typical laying hen, for example, it takes around 20 hours to form a shell.
Pigmentation is added to the outside of the dish by special structures in the fallopian tubes of the bird.
Because eggs are normally blunt ends, this side is normally subjected to more pressure during its journey – and therefore stronger colors.
Birds that nest their eggs open and in a colder climate usually have darker eggshells.
The possible causes of egg colors are varied and contradictory.
For example, dark pigments absorb more heat than their lighter counterparts, which could suggest that dark eggs would be preferred in cooler areas.
On the other hand, dark eggs protect better against harmful UV rays, which are usually more intense in warmer areas.
They also have stronger antimicrobial properties, which are more useful in warmer climates – together suggesting that the opposite could be true.
Similarly, the striking nature of lighter eggs could be expected to be a disadvantage in warmer areas, where predators tend to be more abundant.
To settle the matter, measure C.W. biologist Phillip Wisocki. Post Campus from Long Island University and colleague & # 39; s the clarity and color of eggs, from 643 bird species, preserved in the collection of various natural history museums.
The authors then mapped these colors to the well-known geographical breeding area of each species – and found a pattern.
& # 39; Birds that live in cold habitats, especially those with nests exposed to incident solar radiation, have darker eggs & # 39 ;, the researchers wrote in their article.
Eggs, on the other hand, lie in warmer climates, or in cavities or enclosed nests, which are usually lighter in color.
The team then exposed chicken, duck and quail eggs – in different colors and brightness – to direct sunlight.
They discovered that eggs with a darker pigmentation could maintain their incubation temperatures longer than their lighter counterparts.
Researchers measured the brightness and color of eggs, of 643 bird species, preserved in the collection of various natural history museums. The authors then mapped these colors in the well-known geographical breeding area of each species, as shown
& # 39; Birds that live in cold habitats, especially those with nests exposed to incident solar radiation, have darker eggs & # 39 ;, the researchers wrote in their paper (stock image)
& # 39; This evidence suggests that egg pigmentation could play an important role in thermoregulation in cold climates & # 39 ;, the researchers wrote.
While, she added, a series of competitive selective pressures further impact eggshell colors in warmer climates. & # 39;
The full findings of the study were published in the journal Nature ecology and evolution.
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