Alcatraz wildlife affected by oil spill

July 1, 2008 3:05:16 PM PDT
You are more likely think of Alcatraz Island as a tourist attraction than a breeding ground, but it is just that. In fact, thousands of birds return to "The Rock" each year to mate and raise their young.

From the shore, you can see just how isolated Alcatraz Island is. Thousands of tourists a day are ferried out to the former penitentiary for a look back at a time now lost.

The residents of Alcatraz are long gone, but the original settlers have returned. That is, the thousands of birds that colonize the island.

"It is a significant breeding location for sea birds and water birds," said Bill Merkel from the National Park Services.

Merkel oversees the natural resources of the island, including the feathered ones.

"Initially, these islands didn't have human occupants and regular human presence so it really was probably a seabird island," said Merkel.

But as the island evolved from a Civil War fort, to a military prison, to a federal penitentiary, the birds paid the price.

"The heavy occupation and the heavy modification of the island and very likely the persecution of birds probably lead to a near removal of - near extrication of birds from the island," said Merkel.

Shortly after the Park Service took over the management of the island in the early 1970's, the birds began to return.

Over the last 30 years, the bird populations have continued to grow. Today, it is the largest breeding ground for sea birds in the San Francisco Bay.

But future growth could be stifled by last November's massive oil spill in the bay. That's when the Cosco Busan struck the Bay Bridge, dumping 58,000 gallons of bunker fuel into the bay. Nearly 2,000 birds were killed, and nearly 1,000 were cleaned and released.

Fortunately, November's spill came after most of the breeding birds had flown away for the season. Most birds breed here from February to September.

"The numbers seem to be fewer this year, as far as breeding birds here," said researcher Sara Acosta from PRBO Conservation Science.

Researchers from PRBO Conservation Science are keeping a close eye on this year's breeding season. The season has gotten off to a late start, but it's too early to tell whether the oil spill is the reason.

"These birds are feeding in the bay and of course the bay, you know, there's probably oil that's settled to the bottom. That's gotten to the food chain. There are so many factors that go into how successful these birds are and what's affecting them, so it's not just oil spill here in the bay but also like climate," said Acosta.

A drier season and the record setting heat wave last month may have also have an impact on the overall breeding season.

"We saw a lot of heat stress symptoms like panting and vomiting in the birds, and we even saw an unprecedented mortality in some of the birds here on the island," said Acosta.

The full effect of the spill may not be known for generations. In the meantime, researchers say they will be watching the birds of Alcatraz, and they hope visitors will come out and see firsthand, as nature takes it course.

"It's probably one of the public's best opportunities to view breeding sea birds, colonial nesting sea birds up close," said Merkel.

The next big gauge of the impact of the Cosco Busan oil spill will come this November. That's when wintering birds will return to the bay.

Written and produced by Ken Miguel.


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