Intensifying tropical storms threaten Seabirds, New research

Last year, a powerful cyclone struck a remote Australian island, decimating seabird populations and wiping out up to 90 percent of some species. Scientists are worried that climate change-fueled storms could push some birds to extinction.

In April 2023, Cyclone Ilsa, a Category 5 storm with 136 mph winds, hit Bedout Island off Western Australia's Pilbara coast. What researchers found afterward was shocking: tens of thousands of dead birds.

"In my 20 years as a seabird expert, I've never seen anything like it. We lost 20,000 to 30,000 breeding-age seabirds almost instantly," said Lavers, who coordinates Adrift Lab, an international research group focused on seabirds and marine plastics research, and is also an adjunct researcher at Charles Sturt University in Australia.

Unprecedented mortality

The study, published this week in the journal Communications Earth & Environment, reveals that 80 to 90 percent of three bird species on the island perished in the storm. These include masked boobies, brown boobies, and lesser frigatebirds.

Lavers and her team found utter devastation on Bedout Island after the cyclone. Most birds had died in place, and many chicks and eggs were buried under sand and debris.

"There were carcasses everywhere. It was heartbreaking," Lavers said.

The findings challenge the belief that seabirds are good at sensing and escaping big storms. The new study suggests they're not invincible, while research shows birds can flee or fly into a hurricane's calm eye.

"It's given us a false sense of comfort," Lavers said. "We say, 'Don't worry, the birds will flee to the ocean.' But that's not always true. Some events cause major deaths."

One puzzling discovery was that the birds on Bedout Island didn't try to escape. Lavers said, "They basically died where they sat. We found no evidence they attempted to flee. I don't have an explanation for that."

Did the storm intensify too quickly? I find that hard to believe, but I don't have an answer," Lavers admitted.

Climate change threatens seabird populations with storms

If tropical storms keep getting stronger and more frequent due to climate change, some seabird populations could be in serious trouble.

Ryan Huang, a tropical conservation expert not involved in the study, explained, "When 90% of a local population dies, "it becomes vulnerable to imbalanced sex ratios, illness, or another disturbance. A couple of difficult years can lead to extinction."

Seabirds are vital in island and reef ecosystems, transporting nutrients from the sea to land through their droppings and supporting plant and animal life. Their decline could have extensive impacts.

The masked booby subspecies on Bedout Island, found nowhere else, is especially at risk. Only 40 breeding pairs remained weeks after the cyclone.

"More than 20,000 animals were lost," Lavers said. "Recovery will be slow and likely interrupted by another cyclone."

Cyclones hit Bedout Island every seven years

The study notes that cyclones strike Bedout Island every seven years on average. This might not give birds enough time to recover between storms.

While writing the paper, Lavers watched anxiously as two more cyclones approached the island. "My anxiety was extremely high," she said. "It's been less than a year since Cyclone Ilsa, and another major storm was heading that way."

After reflecting on the current circumstances, Lavers realized the dire situation facing seabirds and wildlife. "This is the reality for many seabird hotspots and sea turtle nesting areas," she said.

Concerns have been raised about coral reefs not recovering between bleaching events and forests struggling to regrow between more frequent wildfires.

The study serves as a wake-up call that even storm-savvy animals may not be ready for what's coming. "We need to be real about the scale of mortality we're facing," warned Lavers.

She hopes the findings will spur action to address climate change and protect vulnerable species. Better monitoring of remote islands is crucial to document unnoticed wildlife losses.

The surviving seabirds on Bedout Island face a precarious future. They must rebuild their colonies before the next big storm.