West Nile may imperil threatened scrub jay

Scientists fear that the bird's susceptibility to other kinds of mosquito-borne encephalitis will make it especially vulnerable.

By WES ALLISON

© St. Petersburg Times,
published September 4, 2001

The Florida scrub jay has survived strip malls and beach homes, highways and a near-end to the wildfires that once rejuvenated its habitat. Barely.

Now, just as scientists are trying to understand the effect of the West Nile virus on people and horses, bird experts are carefully monitoring the beleaguered jay, which they fear may fall prey to the virus as it moves into Central Florida.

The scrub jay, officially designated a threatened species, is expected to be especially vulnerable to West Nile because of its historic susceptibility to other forms of mosquito-borne encephalitis.

Its close cousins in the corvid family, the American crow and the common blue jay, have been especially hard-hit by West Nile, dying in droves in areas where the virus has been discovered.

"The problem that we face with scrub jays is they are already so precarious, their numbers are so low, that we worry about catastrophic events," said Nancy Douglass, a regional wildlife biologist for the Florida Fish and Wildlife Conservation Commission based in Lakeland.

"A robust population, with lots of animals, can afford to lose quite a few. When you have a population that is no longer robust, you tilt the scales toward extinction."

West Nile has not yet moved into the central and south Florida counties where the scrub jays are most common, but that is expected to happen. Officials with the U.S. Fish and Wildlife Service, the state Fish and Wildlife Conservation Commission, the U.S. Forest Service and the state parks department are setting up a system for watching and testing the birds so they will know if West Nile hits them.

Scrub jays nest in the low sand pines and scrub oaks on sandy ridges. They are tenaciously territorial, and single birds will stay put, even if it means never mating.

Ornithologists believe they live in small family groups, with each year's hatchlings staying on for a year to help the mother and father care for the next generation, said Rich Paul, manager of the Florida Coastal Islands Sanctuaries for Audubon in Tampa.

"It's a remarkable lifestyle social organization," he said. "Apparently it takes that many adults finding food to raise the kids substantially."

West Nile is carried by birds and transmitted by mosquitoes to other birds, horses and humans. In the United States it was discovered in New York in the summer of 1999 and has moved steadily south, having been found in North Florida and the Keys just this summer. It has sickened four people, most recently a Sarasota woman who apparently was infected during a July visit to the Keys.

Although West Nile has been detected in more than 60 species of birds and likely has killed hundreds, if not thousands, widespread deaths probably won't be a routine summer occurence.

Because West Nile is new, native birds have no immunity to it. That makes them very vulnerable, just as Native Americans were vulnerable to diseases brought to the New World by colonists and conquistadors. Over time, the bird populations should develop widespread immunity.

"Everything it touches is susceptible to it," said Dr. Steven Wiersma, acting chief of the Bureau of Epidemiology for the state Department of Health.

"The ratio, that balance, changes the longer a virus is present in an area, and it will reach some kind of cyclical level."

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