HYPOTHESIS - WEST NILE
VIRUS SURVIVOR
On November 6, 2003 we captured two American
crows in our box trap in Jeffrey City (chopped up bacon is good
crow bait). Both crows were immature birds based on plumage and
roofs of their mouths were pink. One appeared to be normal (wing
chord was 308 mm), however, the other appeared to be stunted
(wing chord was 273 mm) and had feathers with prominent stress
marks on both the retained immature feathers and the emerging
new feathers. The stunted bird was growing a new tail which was
about a third of the normal length. We think this bird was a
survivor of West Nile Virus (WNV), as one of the symptoms is
the "pinching off" of feathers in the blood, causing
them to fall out. This is what we believe happened to this crow
and the bird survived WNV infection and is now recovering and
growing a nearly normal tail. The bird did not appear sick at
time of capture as you can see below.
Here is a photo of the crow's wing feathers showing frayed ends,
prominent stress marks up about 2" then near normal feathers.
The near normal portions of feathers were probably growing in
after the initial infection was brought under control, while
the poorly constructed feather tips were coming out during the
time the crow was fighting an acute infection.
Newly emerging tail with stress marks everywhere. The brownish feather that barely shows peeking out from under the end of the tail is a very tattered and faded retained immature undertail covert. It illustrates the shortness of the new tail feathers.
Lance & Jill Morrow
Author contact information:
Jill Morrow, Ph.D.
Post Office Box 430
Jeffrey City, Wyoming 82310
Phone: 307-544-9009
Email: jmorrow@trib.com
