crows-eye




Eye to eye

Originally uploaded by Harry Mijland (dear harry)

Artificial light assist crows in watching for owls. I have noticed that many urban crow roosts are not located in nice dense trees where the crows would have microclimate advantages, such as protection from wind or cold. Rather, the crows perch out on the tips of bare branches of leafless deciduous trees. I was quite surprised by this at first, but then I noticed that many (most?) roosts are located near sources of bright illumination, such as streetlights and parking lot lights, like the lights at the Auburn prison and Syracuse University. It makes sense for crows to like “nightlights” to protect them from their biggest bogeyman, the Great Horned Owl. Crows don’t see well at night; owls do. Crows near street light could see approaching owls. Also, if a crow gets scared out of its roost in the middle of the night (presumably by an owl taking crows), in lighted urban areas the crows can see where the predator is, and perhaps more importantly, can see to find another perch. You can imagine that flying blindly into the dark is not something any bird would choose to do. I was surprised at the amount of activity at the Auburn roost well after dark. The crows were still making a lot of noise and even flying from tree to tree. In other roosts I have watched that were in darker locations the crows quieted down rather quickly and no movements between trees were seen shortly after complete darkness.1

  1. http://www.birds.cornell.edu/crows/crowfaq.htm []

Deformed beaks…a mystery

deformed

Birds’ beaks are made of keratin, similar to human fingernails and hair. Normally, beaks wear down with use, continuing to grow at the same time. There’s a balance. But something is causing this super-fast growth — and it doesn’t get turned off. There seems to be a concentration in the Pacific Northwest and Alaska but the cause is unknown still.

read more | digg story

Read more about this mystery at the Alaska Science Center or the Falcon Research Group or the University of Michigan Dearborn.

Corvid Abnormalities

Abnormalities can be found in all life forms–corvids included. Here are some interesting photos I found of corvids with two abnormalities deformed beaks and partial albino-ism–leucistic or albino corvids.

crows_partially_albino
Leucistic (partially-albino) crow

Albino Steller's Jay
Albino Steller's Jay

Leucistic (partially-albino) magpie (Photo from Messybeast.com)
Leucistic (partially-albino) magpie (Photo from Messybeast.com)

Leucistic (partially-albino) Jackdaw (Photo Source: Surfbirds.com)
Leucistic (partially-albino) Jackdaw (Photo Source: Surfbirds.com)

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Raven with a deformed bill

Crow with deformed beak
Crow with deformed beak

Crow with deformed beak
Crow with deformed beak

Steller's Jay with deformed beak
Steller's Jay with deformed beak

Read about THE MYSTERY OF THE LONG-BEAK SYNDROME here. Or you can read Passerines with Deformed Bills by Julie A. Craves (an article) here.

There seems to be a high concentration of birds with deformed beaks in the Pacific Northwest–I wonder why.