Biology Reference
In-Depth Information
close to the skin's surface, and when the cranes are engaging in sexual or territorial dis-
plays, the papilla become engorged with blood, appearing brilliant red. To further con-
fuse the matter, fine, very thin black plumes lie on top of the red skin, contributing to the
feathery appearance.
Brightly colored skin on faces and heads of birds is not uncommon.
Health and Beauty Aids
Q I just saw a totally bald-headed Blue Jay! At least I think it was a Blue Jay. Why
was it missing all its head feathers?
A
When some individual birds molt, their head feathers drop out nearly simultan-
eously. No one has figured out why this happens so frequently in Blue Jays and North-
ern Cardinals, especially because some individual cardinals and jays seem to molt only a
few head feathers at a time, as do other species. Is it significant that these two unrelated
species are crested? This is very unlikely, because some crestless birds, such as grackles,
sometimes lose all their head feathers, too.
Some people have speculated that bald birds are plagued with mites, but this is un-
likely. For several years I had two Blue Jays housed side by side in my rehab facility.
Every fall one of them, Sneakers, lost all its head feathers at once while its neighbor, BJ,
with whom it shared food, never molted all its head feathers. If one of them had mites,
the other probably would have. It seemed to be an individual quirk.
Q Birds always look worse when they leave my birdbath than when they arrived!
Why do they bother?
A
Wet feathers do indeed look scraggly! Birds bathe to get clean, but when they step out
of the bath, their feathers look as unkempt as our hair does just after washing. Birds dip
in the water while opening their feathers. If they're in a completely secluded area and
haven't detected any potential predators lurking about, they may splash and shake and
soak through the outer feathers to the down and skin beneath. Then they fly off to preen
in a safe hiding spot, nibbling off remaining dirt, parasites, and oils. It is astonishing how
quickly the feathers dry and how automatically they resume their shape.
