Friday, 24 July 2009
Bleaching of BLUE-CHEEKED BEE-EATERS
Hi Lee, Interesting record & photos.
In east Saudi Arabia, autumn Blue-cheeked Bee-eater passage is typically October into November. The birds are not as green, nor bright, contrasty & irridescent as in spring/breeding plumage (April/May): they are more faded, even the "blue cheek".
However, I have never seen anything quite like your "bleached" adult example. The attached resized autumn image (lower image, taken 12-10-06) shows you can still clearly differentiate the remaining blue cheek (e.g. supercilum) from the green crown/upperparts etc.
Comparison with an adult spring (top image, taken 12-5-08) shows the much drabber autumn plumage. However, both autumn & spring adults do show some blueish in the rump area, that is more extensive on the autumn birds. On the autumn birds, this blueing also extends onto the secondaries, leading edges of the primaries & tail, suggesting that the worn, sun-affected areas do tend to turn to a bluer/turquoise shade.
Could this be an extreme effect of the much higher temperatures experienced in the breeding range this year, since there have reportedly been summer heatwaves all across Europe/West Asia? (Dr. Graham R. Lobley)