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月別アーカイブ

 2009年12月 

Tendency of Colouration of Owls 

Some species of owls have different plumage among same species.


Brownish Great Horned Owl,
IMG_8695.jpg

and the same species with whitish colouration.
IMG_8697.jpg


This is a dark brown American Wood Owl,
IMG_8672.jpg

and this is the same species with paler plumage.
IMG_8677.jpg


Normal brown Burrowing Owl,
IMG_8701.jpg

this one is somewhat paler.
IMG_8702.jpg


Greyish Spotted Eagle Owl,
IMG_8693.jpg

while this is brownish.
IMG_8686.jpg


Barn Owl with pure white belly,
IMG_8678.jpg

and the one with black dots.
IMG_8679.jpg


In general, birds in more humid habitats tend to be darker than their relatives from regions with drier climates(Gloger's rule), and their body mass increases with higher latitude and colder climate(Bergmann's rule).


These are achieved for their living, to conseal themselves from their prey and to keep their heat.


Having some careful looks at the owls asleep in the Garden, you might encounter the miracle story of evolution.....

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