What happened to all the magpies?

September 18, 2005

Q: I usually see a lot of yellow-billed magpies around, but I haven't seen any for quite awhile. Is this because of West Nile virus?

A: The loud, upbeat squawking of the Central Valley's "signature" bird, the yellow-tailed magpie, has been largely silent, and West Nile is believed to be the cause, according to Holly Ernest, a University of California, Davis, veterinarian and expert on wildlife populations.

Ernest said she has received hundreds of e-mails from Central Valley residents asking about the absence of the black-and-white birds, which are found only in California.

"We are concerned that mortalities due to this epidemic may endanger the existence of the species," said Ernest and fellow UC Davis veterinarian Walter Boyce.

Ernest is seeking "citizen biologists" to count magpies and two of their close relatives that are also affected by West Nile, jays and crows.

For more information go to the Web site www.vgl.ucdavis .edu/wildlife/projects_magpie.html; or e-mail Holly Ernest at wildlife@vglucdavis.edu.

No estimates are available on magpie deaths, "but we know at least thousands have died," she said.

Ernest is leading a study to determine whether West Nile is causing a loss of genetic diversity that could make magpies and other birds less able to cope with environmental changes, including diseases.

Steve Emmons, a biologist at the Sacramento National Wildlife Refuge near Willows, was less sure that West Nile virus is to blame. A food shortage may have caused magpies do go elsewhere temporarily, he said.

"A lot of times more than one factor exists when you see a population decline," said Emmons.

Ron McBride, manager of the Yuba-Sutter Mosquito and Vector Control District, said the four birds most affected by West Nile - magpies, jays, crows and ravens - have experienced a 61 percent population drop statewide.

McBride, while not a wildlife expert, said populations may return to normal levels once birds develop West Nile antibodies, probably after three or four generations.

A task force met last week to discuss whether some magpies may have migrated to the foothills, said McBride.

Since You Asked runs on Sundays. It is written by reporter Rob Young. Questions can be sent to him in care of the Appeal-Democrat, P.O. Box 431, Marysville, CA 95901; or faxed to (530) 741-0140. You also may e-mail him at ryoung@appeal-democrat.com.