The Sacramento Bee                               Saturday, August 13, 2005; A1

W. Nile's toll on birds is soaring

The yellow-billed magpie
could disappear as virus
spreads in north state

By DEB KOLLARS
Bee Staff Writer

    As West Nile virus has moved into Sacramento County with a vengeance, it has killed thousands of birds and left wildlife experts worried about the survival of one of Northern California's more striking and clever birds: the yellow-billed magpie.
    Sacramento County has not only the highest number of confirmed human cases of West Nile in the state, but also far and away the highest number of birds that have died from the disease.
    According to figures released Friday by the state Department of Health Services, the number of reported dead birds in Sacramento County was 12,198 so far in 2005, representing 17.6 percent of the total 69,203 dead bird reports for the state's 58 counties.
    Although not all the birds have been tested - state scientists stop testing once they've established West Nile has invaded an area - the state's top West Nile experts said there is no question the high dead bird counts stem from the disease.
    The actual numbers could easily be 10 times as high as those reported because many people do not report dead birds, said Stan Husted, supervising public health biologist for the state Department of Health Services.
    "It's all happening very fast," Husted said.
    Sacramento County's tally of confirmed human cases of West Nile remained at 36. Statewide that number rose from the 118 reported Tuesday to 174 Friday, with four people reported dead this year from the disease.
    The emerging concerns about birds came as mosquito control experts prepared for a second night of aerial spraying in southern Sacramento County. They also announced that infected mosquito counts were rising in Yolo County and may require insecticide treatments in populated areas in future days - most likely with ground rigs on city streets.
    "I don't think we're going to have to do aerial applications over the cities of Davis and Woodland," said Dave Brown, manager of the Sacramento-Yolo Mosquito and Vector Control District. "We believe we can handle them with ground-based units."
    The district is doing the treatments to stop the spread of West Nile, which is passed by infected mosquitoes.
    As the new numbers rolled out late Friday afternoon, officials of the mosquito control district were keeping an eye on the weather. Plans to spray 66,000 acres south of the American River were thwarted on Friday night. Planes were grounded after Delta winds picked up.
Sacramento County is not the only hot spot.
    This summer, the mosquito control district has been using ground rigs to control mosquitoes in cemeteries and parks in various Yolo County locations, as well as the fairgrounds in Woodland. Agricultural areas of Yolo County have been receiving regular aerial sprayings, as they do every year, Brown said.
    As of Friday morning, the district had spent about $400,000 on plane and materials costs for four nights of spraying. The district has about $1 million in reserves to cover all spraying costs.
    Brown said traps in the northern areas of Sacramento County showed kill rates of between 40 percent and 80 percent, depending on the location, after three nights of aerial spraying.
    For many people, their first and only encounter with West Nile comes when they stumble upon a bird that has succumbed to the aggressive disease.
    A dead jay in a flower bed. A dead crow on the bike trail. A dead magpie lying in the street.

    The images have been haunting Sacramentans, and have provided a sobering record of the rapid spread of West Nile.
    Bobbi Larsen, a retiree living near Fair Oaks Boulevard and San Juan Avenue, is among many who have discovered birds wobbling on the ground, or already dead.
    "In one week's time, we've had 13 dead magpies on a tiny little section of our street," Larsen said. "I had a scrub jay who came every day at lunchtime and squawked for joy in the birdbath. Now he's gone."
    Dawn Austin, a painting contractor who lives near Orangevale, said she buried one bird after another this week under an oak tree on her small acreage. Most were jays and magpies.
    "I used to fill my bird feeder every day," Austin said. "Now, it's every four days or so."
    Many have mistakenly concluded the birds are dying from the aerial spraying.
    "It's not the spray. It's the virus," said Vicki Kramer, chief of the state health department's Vector Borne Disease Program.
    Birds play a critical role in the spread of West Nile virus. Birds are a favorite target of mosquitoes. When bitten by infected mosquitoes, birds can become "reservoirs" for the virus, passing it along to uninfected mosquitoes that bite them. Mosquitoes, in turn, infect people, horses and other animals; bird-to-human transmissions do not occur.
    Some species of birds are more vulnerable than others. The "corvid" family - which includes crows, jays, magpies and ravens - is particularly susceptible. Nearly 100 percent of infected crows die, usually in about five days, with the other corvid types not far behind, Husted said.
    Wildlife experts are especially worried about the yellow-billed magpie, said Dr. Holly Ernest, a wildlife veterinarian who directs the Wildlife Genetics Lab at the UC Davis School of Veterinary Medicine.
    One clue the bird is in danger is that the black-billed magpie, which lives throughout western North America (except in areas populated by the yellow-billed) has been hit hard by West Nile.
    The yellow-billed magpie is not listed as a threatened species. But because it is endemic to California, meaning it lives nowhere else, a large kill-off could place the bird at risk of survival, Ernest said. She is involved in several research projects to monitor the disease's impact on the local magpie, including counts being conducted by volunteers from Davis as they ride their bicycles.
    A wide range of other birds such as finches, robins, quail, mourning doves and certain parakeets also can become infected with West Nile. They survive or die at varying rates, depending on the type of bird, said Nicholas Komar, research biologist for the Centers for Disease Control and Prevention in Fort Collins, Colo.
    Birds remain infectious for several days. Those that become infected but survive become immune for life and can pass that immunity to their offspring, Komar said. Eventually, the disease will run its course, he added, but based on other areas of the country, it could take several years. In New York, bird deaths have been a regular summer ritual since West Nile first hit in 1999.
    The disease attacks most of the major organs and neurological systems, leaving birds staggering and unable to move in the final stages. Gauging pain levels in birds is difficult, but researchers said birds with West Nile almost certainly suffer. The only way to stop birds from becoming infected is to reduce infected mosquito populations, Husted said.
    The dead bird reports were a major clue to local officials that the disease was spiraling and aerial spraying was needed. "That was one of the triggers that told us we had a problem," Brown said.

The Bee's Deb Kollars can be reached at (916) 321-1090 or dkollars@sacbee.com.