Thousands of seabirds were killed when the tsunami generated by last week's massive earthquake off Japan flooded Midway, a remote atoll northwest of the main Hawaiian islands, a U.S. wildlife official said Tuesday.
At least 1,000 adult and adolescent Laysan albatross were killed, along with thousands of chicks, said Barry W. Stieglitz, the project leader for the Hawaiian and Pacific Islands National Wildlife Refuges.
Many drowned or were buried under debris as waves reaching 5 feet (1.5 meters) high rolled over the low-lying atoll about four hours after the magnitude-9.0 earthquake struck Friday.
The white-and-black feathered Laysan albatross is not in danger of becoming extinct. About 1 million of the birds live at Midway Atoll National Wildlife Refuge about 1,300 miles (2,100 kilometers) northwest of Honolulu, making it the largest Laysan albatross colony in the world.
But Stieglitz said the deaths could account for a significant share of Laysan albatross chicks hatched during the current season.
"We may see just a slight decline in breeding birds next year, next year and the year after that," he said. "There will be a gap in the breeding population when these birds that would have grown up this year, would have matured and started breeding for the first time."
The waves hit each of the three islands inside the atoll.
Spit Island, about 15 acres (six hectares), was completely overrun. The tsunami washed over 60 percent of Eastern Island, an islet of nearly 370 acres (150 hectares). Waves also covered 20 percent of Sand Island, the largest of the three at almost 1,200 acres (485 hectares).
Biologists are less sure how many ground-nesting bonin petrels may have died, because these birds live in underground burrows and would have been buried in areas covered by waves. Stieglitz estimated the death toll would reach the thousands.
Since the bonin petrel feed at night, however, Stieglitz said he was hopeful many were out foraging when the tsunami hit before dawn.
Stieglitz said many wildlife populations rebound from natural disasters like this. But he said the tsunamis aren't helpful to species facing threats like climate change, a loss of habitat, and invasive species.
"When you start piling the natural catastrophe on top of invasive species invasions and all of these other things, it makes the population a lot less resilient and more susceptible to extinction," he said. "It's rather unfortunate timing, in our eyes. Not that there is ever a good time for this, but there are better times than worse times. And in this era, this is a worse time."