When tropical cyclone Ilsa hit western Australia in April last year, few had their sights set on Bedout Island, a small cay that’s an important seabird breeding site.
Terns, gulls, frigatebirds and a rare subspecies of masked booby nest on the island. The Category 5 storm stripped the island bare of foliage, and large waves flooded its shallow sands.
A study published earlier this month estimates that the hurricane killed between 80 and 90% of the island’s seabirds, offering a grim prediction of natural disasters’ impacts in the age of climate change.
“It was heartbreaking to see hundreds of carcasses strewn across the island’s surface,” said Jennifer Lavers, the lead author of the study, in a research summary posted to YouTube.
Hawaiʻi is known for its diversity of native forest birds and seabirds, many of which are found nowhere else in the world. The islands supported at least 113 species of endemic birds, prior to the arrival of humans, but habitat destruction and the introduction of invasive predators have brought many others to the brink of extinction.
As climate change increases the frequency and severity of natural disasters like hurricanes, experts warn that birds will bear the brunt of these storms in varied and long-lasting ways.
“Hurricanes do obviously have a huge impact on the humans, but they have equally large impacts on both our oceangoing birds and our forest birds up in the landscapes of Hawaiʻi,” said Chris Farmer, the Hawaiʻi program director at the American Bird Conservancy.
How hurricanes affect Hawaiʻi’s birds
Despite predictions that this hurricane season is expected to yield a below-average number of severe storms in the Central Pacific, climate change has already led to more of these events. A 2023 study found that an observed increase in the frequency of severe storms that hit Hawaiʻi in the last 20 years was likely related to greenhouse gas effects.
Hurricanes threaten seabirds and forest birds in different ways. Birds like the mōlī (Laysan albatross), and pākalakala (grey-backed tern) nest in low-lying sandy areas in the Northwestern Hawaiian Islands. Large waves from hurricanes can cause beaches to flood, drowning eggs and nestlings or smothering them in the sand.
Importantly, certain species of seabirds have evolved adaptations that allow them to survive high-speed winds and severe storms. At least two species of seabirds have been observed flying directly into the eyes of hurricanes, which researchers hypothesize helps them avoid the impact and not get blown off course. But this strategy is still relatively risky and leaves eggs and nestlings unprotected.
“Even though they've evolved with these kinds of events, it's when we think about [hurricanes] being more intense, and when we think about them in combination with other climate change impacts — like sea level rise, or other threats like oil pollution, or invasive species — that climate change is going to exacerbate and create new challenges for seabirds, both at sea and on islands,” said Nick Holmes, the associate director for oceans at The Nature Conservancy.
Two hurricanes that hit Hawaiʻi in the 1980s and 90s showed the havoc the storms could wreak on vulnerable forest bird populations. Hurricane Iwa in 1982 likely led to the death of one of two remaining Kauaʻi ʻōʻō. The lone surviving bird was last recorded in 1987 and may have been lost in 1992’s Hurricane Iniki.
The storm itself or its fallout — the destruction of old-growth forests and regrowth of non-native foliage in their place — led to the extinction of two other Kaua‘i forest birds: the kāmaʻo and ‘ō‘ū. In many ways, reverberations from Hurricane Iniki can still be seen in Kaua‘i forests today, said Cali Crampton, the program manager of the Kauaʻi Forest Bird Recovery Project.
“It really leveled us like matchsticks,” Crampton said. The loss of native forests put birds, “in a precarious position that left them more vulnerable to everything that came thereafter, namely avian malaria,” she added.
How conservation scientists are preparing for the next storm
Experts stressed that there isn’t a silver bullet to the threat of hurricanes. On the other hand, many of the initiatives to bolster birds’ habitat and their populations will generally make these ecosystems more resilient.
Bird conservationists in the state have wrestled with the idea of translocating some birds, or moving them to islands where they have never lived before in order to give them a fighting chance, said Farmer.
This technique could be especially useful for birds that breed exclusively on low-lying islands and atolls that are at risk of flooding during a storm. Scientists from Pacific Rim Conservation have also transplanted seabirds to Mexico and established new breeding colonies of birds like the mōlī and ka‘upu (black-footed albatross).
Another strategy is restoring seabird and forest bird habitats by walling off priority areas and removing invasive species within them — what Holmes called “islands within islands.” In some cases, like on Lehua Island, officials have been able to eradicate rabbits and rats, and seabirds have flourished in their absence.
“What that does is it strengthens the resilience of those seabird populations in those places, and then it buys them a better chance of being able to persist in the future,” Holmes said.
For critically endangered forest birds, the situation has gotten dire enough that scientists are considering captive breeding programs to build out insurance populations of birds like the ʻanianiau, Crampton said.
This way, a single event like a hurricane will have a lower chance of wiping out an entire species. Still, when Hurricane Douglas narrowly missed Kauaʻi in 2020, Crampton immediately thought of the devastation of Iniki and its impact on the forest birds.
“We all were sitting here thinking in the middle of the pandemic that this is also the last time we were ever going to see an ʻakikiki,” she said. “Every time a hurricane comes that close to us, we’re like, ‘Which species are we going to lose next?’”
