Gentoo beak colour, chick and adult
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gardenmaeve
moderator
There are still many questions regarding whether the Gentoo penguin's red/orange beak spots are related to sexual development and selection or relative physical condition including carotenoids from krill (or both!). "The questions of whether carotenoids are mobilized from storage organs or the blood during food shortages or in stressful situations and the amount of carotenoids available in these situations remain contentious. " Found here
The Gentoos in this image are moulting; a likely reason for the chicks' pale beaks. We know the beak spot colouration from krill consumption fades after about a week when no krill are being consumed (Information here) , as in fasting during moult.
According to the study in the first link: "We study the amount of carotenoids circulating in the blood stream in Gentoo Penguins (Pygoscelis papua), taking advantage of the physiological stress produced by fasting during moulting. Carotenoids are not detectable in the blood after 1 week of fasting during moulting in Gentoo Penguins, whereas breeding adults and chicks show a high concentration of astaxanthin."
So while chicks' beak spot colour may be lighter at times than those of adults, we can't rely upon it to classify chicks during moult. One P.W. example showing stronger beak spot colour in Gentoo chicks.
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AvastMH
moderator
That's fascinatng information @gardenmaeve. Many thanks. 😃
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gardenmaeve
moderator
I haven't looked for information on your query though, @AvastMH..." I wonder if the pink of the krill leaches out into the adult's stomach prior to regurgitation?" and it's a good question!
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Fascinating! Thanks @gardenmaeve
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