Costs for birds could soar - A huge flock of cormorants already is raising the price of painting the bridge, and higher costs could be added to the bill.

Christopher Dunagan
Bremerton Sun Staff

July 24, 2003

Between 500 and 600 rare pelagic cormorants living under Bremerton's Warren Avenue Bridge face an uncertain future as state transportation officials examine the cost of keeping the flock around.

Regardless of whether the birds are driven away temporarily or permanently, they have already become an expensive problem, said Amity Trowbridge, project engineer for the Washington Department of Transportation.

On the other hand, Dave Nysewander of the Washington Department of Fish and Wildlife said biologists were thrilled to discover such a large group of pelagic cormorants in Bremerton -- far from their normal hangouts in rocky cliffs along the Washington coast and San Juan Islands.

"I was excited by the colony because there are so few of them," Nysewander said. "Their numbers seem to have gone down in other places. It would be neat if they could find a way to coexist (with people)."

Not thrilled at all, the Department of Transportation was forced to postpone a $630,000 painting and maintenance project on the bridge after nearly 300 nests -- many active -- were discovered under the structure.

Trowbridge said the delay alone will cost the state money to restructure the painting contract, and now officials must come up with a way to discourage the birds from coming back.

One idea is to remove the nests this fall after all the young cormorants have fledged, then install a net to keep them from coming back, she said. The cost of the net has been estimated at roughly $200,000 on top of whatever it costs to remove the nests.

Other ideas include lights and loud noise to drive the birds away.

It would be cheaper for state taxpayers to exclude the birds permanently, because the bird feces is highly corrosive to the bridge structure, Trowbridge said. Allowing the birds to nest under the bridge is likely to require more frequent painting and expensive sand-blasting -- not the kind of costs the Department of Transportation takes lightly.

Leaving the net up permanently, however, runs the risk of catching and killing some birds, officials said.

Like most birds, cormorants are protected by the Migratory Bird Act, which prevents their killing. Unoccupied nests, however, can be removed without a permit.

Nysewander said pelagic cormorants are found only near saltwater. They are far more rare then their cousins, the double-crested cormorants that sometimes nest along river banks.

Biologists are concerned about pelagics, which might be declining in population, Nysewander said.

He and other biologists are conducting a census of pelagic cormorants to update 20-year-old surveys that no longer reflect reality.

Why the cormorants chose the Warren Avenue Bridge could be a combination of factors, he said.

"In the winter, they move into this area and other protected waters," he said. "Something may have clicked in their minds, and they realized the bridge might just work."

The underside of the Warren Avenue Bridge contains open ledges, like that of the cliffs they like. It also offers some protection against predators.

Another factor is the presence of a pair of peregrine falcons, which are known to drive eagles out of their territories. Eagles can affect the cormorants by attacking them or their young or simply flushing them off their nests.

Nysewander said he doesn't know what would happen to Bremerton's pelagic cormorants if they were excluded from the Warren Avenue Bridge. They might find another man-made structure for nesting, change their nesting criteria or simply fail to nest at all.

Trowbridge said discussions about what to do are just beginning, and transportation officials will work with state and federal biologists to come up with a solution.