Albinism and leucism
|[Note Guidelines] Photographer's Note|
|Jackdaws are supposed to be black. This one is leucistic.|
I saw it from the car. I had to park immediatly and try to approach on foot. He wasn't shy. I could come as close as 2 m. He would then fill the all frame. Looking for food he even came at 1 meter distance from me. I couldn't believe how lucky I was. I saw leucistic birds before but rarely and they were very shy. I went on my knees for a more horizontal view. It's the only good pic of a series of 174: he was hectic and there wasn't much light.
Note the blue eyes. This is the same color as those from the usual black jackdaws. Those are not sensitive to the sun light (only red ones from albinos specimens are)
The Jackdaw (Corvus monedula (Lat), Choucas des tours (Fr)) is one of the smallest species (34–39 cm in length) in the genus of crows and ravens. It is a black-plumaged bird with grey nape and distinctive white irises. Like all corvids, it is omnivorous. It is found across Europe, western Asia and North Africa.
ALBINISM AND LEUCISM:
Leucism is a condition characterized by reduced pigmentation in animals. Unlike albinism, it is caused by a reduction in all types of skin pigment, not just melanin.
Leucism is a general term for the phenotype resulting from defects in pigment cell differentiation and/or migration from the neural crest to skin, hair or feathers during development. This results in either the entire surface (if all pigment cells fail to develop) or patches of body surface (if only a subset are defective) having a lack of cells capable of making pigment.
Since all pigment cell-types differentiate from the same multipotent precursor cell-type, leucism can cause the reduction in all types of pigment. This is in contrast to albinism, for which leucism is often mistaken. Albinism results in the reduction of melanin production only, though the melanocyte (or melanophore) is still present. Thus in species that have other pigment cell-types, for example xanthophores, albinos are not entirely white, but instead display a pale yellow colour.
More common than a complete absence of pigment cells is localized or incomplete hypopigmentation, resulting in irregular patches of white on an animal that otherwise has normal colouring and patterning. This partial leucism is known as a "pied" or "piebald" effect; and the ratio of white to normal-coloured skin can vary considerably not only between generations, but between different offspring from the same parents, and even between members of the same litter.
A further difference between albinism and leucism is in eye colour. Due to the lack of melanin production in both the retinal pigmented epithelium (RPE) and iris, albinos typically have red eyes due to the underlying blood vessels showing through. In contrast, leucistic animals have normally coloured eyes. This is because the melanocytes of the RPE are not derived from the neural crest, instead an outpouching of the neural tube generates the optic cup which, in turn, forms the retina. As these cells are from an independent developmental origin, they are typically unaffected by the genetic cause of leucism.
Thanks for watching,
cicindela, tomcezar, Argus, anel, mariki, Adanac has marked this note useful
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Hi Jean Marie!
This is amazing shot! In Poland we have some sentence like "to be so rare like white crews" :)
You were very lucky to see this specimen! Most probably it will not survive too long in the wild as it is totaly dufferent from its "cousins", it will be killed by any of predator.
Very educational note too!
TFS this interesting and unique photo!
Interesting photo and notes. A very rare variety of this bird.
A very good photo.
All the best.
- [2008-10-19 22:33]
Is is not often one has the opportunity to photograph leucistic or albinistic birds.
You took the opportunity well to capture this leucistic Jackdaw from your car, though it is a pity the tail did not come into the image. Otherwise it is a sharp capture showing good detail.
Thanks for sharing this interesting contribution,
Very charming picture. Very nice composition on the beautiful bird. Well done.
- [2008-10-25 5:40]
Une image très spéciale que tu nous présentes. Une vue vraiment rare, un corbeau albinos! Là tu as eu beaucoup de chance, surtout que l'oiseau s'est laissé approcher facilement. Une contribution très précieuse pour TN.
Un grand merci
- [2008-10-30 9:47]
C'est vrai que ces choucas sont vraiment très communs ici mais je n'en ai encore pas vu de blanc. Excellent focus. Très bonne exposition et belles couleurs naturelles.
- [2009-01-08 17:42]
Great documentation of this strange condition with excellent notes. Thank you JeanMarie.