Tsunami’s effect on seabirds forecasts toll of sea level rise

The 2011 Japanese tsunami was a disaster not only for humans, but also for hundreds of thousands of seabirds that were swept from the low-lying islands and atolls of the Northwestern Hawaiian Islands.

Now a new study that takes a closer look at the tsunami’s devastation in the islands suggests the episode is a window into the future of what seabird populations face in a world of climate change, sea level rise and increased storm surges.

The study, published Thursday in the journal Ecology and Evolution, urges conservation interests to start preparing now to create new predator-free bird habitat on higher ground.

“We do have the opportunity and the time to build in some resilience for these protected species,” said lead author Michelle Reynolds, a U.S. Geological Service research wildlife biologist based in Hawaii. “Creating new protected areas would give seabird colonies at risk in the future someplace to go.”

Reynolds said she was studying sea level rise at French Frigate Shoals atoll in 2011 when the Japanese tsunami changed her thinking about how exactly seabird species will be threatened by climate change in the Northwest Hawaiian Islands.

While sea level rise is a slow process that will eventually help to submerge the islands, storm surges, tsunamis, king tides and other sudden flooding events — given a boost by growing sea levels — will likely be the first to swamp bird colonies with deadly consequences, according to the scientists.

The study mapped areas where the 2011 Tohoku tsunami flooded the low-lying islands, and estimated the effects of the sudden flooding on 23 bird species nesting on four islands at Midway Atoll and Laysan Island.

With anywhere from 21 percent to 100 percent of each island inundated, the scientists found chick and egg losses exceeding 258,500 at Midway Atoll while albatross chick fatalities at Laysan Island reached more than 21,400.

Only 14 seabird species were nesting when the tsunami struck at night. Nine others were out to sea.

More than 275,000 black-footed and Laysan albatross and Bonin petrel nests were flooded across the four islands, according to the study, and an endangered land bird, the Laysan teal, was particularly hit hard. Its populations declined 40 percent due to sensitivities to habitat changes and tsunami-related avian botulism.

Reynolds said the black-footed albatross is more vulnerable than most seabirds. It not only prefers ocean-front nesting, she said, but it also mates for life and produces only one egg a year.

Many seabird species abandoned the main Hawaiian Islands long ago, landing permanently on the low-lying islands now protected as wildlife refuges and marine national monuments. This happened, in part, because there are no predators there, the researcher said.

But with global warming, change appears to be coming.

“In the future, millions of seabirds will be vulnerable,” she said.

Reynolds said there are lots of places in the main Hawaiian Islands where seabirds can find refuge with the use of predator-proof fencing.

One current example is Kaena Point, home to one of the largest seabird colonies in the main Hawaiian Islands. Recent surveys have estimated that about 2,000 seabirds use Kaena Point as their breeding grounds, with many more using the 59-acre Kaena Point Natural Area Reserve as a place of refuge, according to the state Department of Land and Natural Resources.

Another potential refuge is Kahoolawe. Reynolds said the island, battered by military bombing and erosion, and now on the mend, supported many seabirds at one time.

Not all seabirds are experiencing success in the main islands, however.

A study published earlier this month, led by Andre Raine, director of the Kaua‘i Endangered Seabird Recovery Project, showed that Kauai populations of the Newell’s shearwater declined by 94 percent and those of the Hawaiian petrel by 78 percent between 1993 and 2013.

The seabird species are vulnerable on Kauai to power-line collisions, a perilous attraction to light and predators such as feral cats.

Last week a coalition of conservation groups said it plans to sue the state Department of Transportation for failing to prevent the bright lights of its airports and harbors on Kauai, Maui and Lanai from killing the federally protected native seabirds.