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Date: June 12, 2003
Posted by: Richard Evans (revans@ocvcd.org)

From: "Richard H. Evans" <revans@ocvcd.org>

In reference to the posting concerning WNV and Cedar Waxwings, here in
Orange County in southern California it is not uncommon to have
mortality in this species during the fall migration and to a much lesser
extent, the spring migration. In each of the past 5 years we have
investigated at least one, sometimes two events of between 20-70
mortalities within 48 hours. In each cases, the birds were reported to
be flying erratically, crashing into trees, houses (especially windows),
telephone poles and power lines or aimlessly, staggering ("like they are
drunk") around on lawns, dropping dead. They are always in upscale urban
housing areas in the southern, less populated portions of the county.
2-4 adjacent residences are involved and in all cases Pyrocanthus sp. is
growing on the properties (commonly use for erosion control on coastal
mountain housing developments). Postmortems have been conducted on at
least 50% of birds involved in each episode. Gross lesions of acute
trauma are limited to subcutaneous and calvarial hemorrhage and in some
cases liver laceration and abdominal hemorrhages. Universally,
Pyrocanthus sp. berries have been found in the ventriculus. All have
been negative for WNV by monoclonal immunohistochemistry and serology to
WNV. A search of the literature revealed that it was once thought that
alcohol derived from fermentation of berries produce the above signs,
but chromatographic examination of berries failed to substantiate this.
In our situation this is one of several (not to mention anti-freeze 
poisoning of crows)
wildlife mortality events that must be consider in reference to WNV. In
fact, our program was developed to establish baseline data on wildlife
mortalities in our county from which new and unusually events could be
distinguished (such as WNV).


Richard H. Evans, DVM, MS (Pathol.)
Wildlife Pathologist
WNV Surveillance Coordinator
Dr. James Webb Laboratory
Orange County Vector Control District
13001 Garden Grove Blvd.
Garden Grove, CA  92843
PH: (714) 971-2421
FAX: (714) 971-3940
revans@ocvcd.org

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