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On Kaho’olawe, new technology could restore a sacred Hawaiian island

A red-tailed tropicbird (Phaethon rubricauda)

A red-tailed tropicbird (Phaethon rubricauda), one of the seabirds found on Kaho‘olawe. Image by Meghan Cassidy via Wikimedia Commons (CC BY-SA 4.0).

  • The small Hawaiian island of Kaho‘olawe is a sacred site for Indigenous Hawaiians, who used it for navigational training, religious ceremonies, and fishing.
  • But the island has faced decades of ecological destruction due to invasive plants and animals, erosion, and bombings as a test site by the U.S. military.
  • A new conservation project has successfully tested a novel method using AI-equipped camera traps and an aerial drone to collect images of invasive cats, which have destroyed the island’s seabird populations, in dangerous and difficult-to-access parts of the island.
  • But funding for the work on Kaho‘olawe remains scarce, and the drone project is now on hold as local organizations seek further funding to deal with the feral cats.

To bring seabirds back to Kaho‘olawe, you need to first find the cats. And to find the cats on Kaho‘olawe, you need to know where to find the bombs.

Eleven kilometers, about 7 miles, off the coast of Maui, the island of Kaho‘olawe — the smallest of the main Hawaiian Islands — presents conservationists with a unique opportunity. Small, remote, and sparsely inhabited by humans, it’s almost a perfect location to restore populations of the native seabirds that have been otherwise devastated across Hawai‘i. The one problem? Cats.

Brought to Kaho‘olawe by American ranchers in the 1800s, these feral felines, roughly estimated at 500 to 600 animals, eat seabird eggs and chicks. They also attack the adult birds. But to remove them, ecologists have to navigate a landscape still scattered with unexploded ordnances left by four decades of U.S. military testing.

“Everywhere you look are cats, cats, cats,” says Timo Sullivan, former director of drone programs at the nonprofit Island Conservation, who directed the organization’s prior work on Kaho‘olawe. “There’s almost nowhere safe for seabirds to rest.”

In partnership with Island Conservation and the island’s other conservation groups, the company Conservation X Labs developed a new deployable camera, called Sentinel, that seeks to change the birds’ fate. Sentinel pairs AI-powered camera traps with a remotely operated drone, allowing researchers to collect data on the island’s invasive cats remotely and minimizing the need for travel. The system could be groundbreaking not only for the island’s seabirds, but for a much larger ecological and human network — one that interconnects land and sea, plants and animals, and the health of an ecosystem with the culture and spirit of the Hawaiian people.

“For us, this island is very sacred. It was a center for learning about how you understand nature,” says Davianna Pōmaikaʻi McGregor, a historian at the University of Hawai‘i at Mānoa, and treasurer and secretary of Protect Kaho‘olawe ‘Ohana, the cultural organization that rose out of Native Hawaiian efforts to reclaim the island. “In our dedication, it’s very important that we understand the role of the island and all of its natural life force entities, so that we can reinstate it to its former revered state.”

A flock of wedge-tailed shearwaters.
A flock of wedge-tailed shearwaters. Image by Dominic Sherony via Flickr (CC BY-SA 2.0).
Looking southwest from the air towards Kaho'olawe, with the tiny island crater of Molokini in the bottom right.
Looking southwest from the air towards Kaho’olawe, with the tiny island crater of Molokini in the bottom right. Image by Momi Wheeler/Protect Kaho’olawe Ohana.

Invasive species and bombs

For centuries, Kaho‘olawe was a center of navigational learning, where young sailors would go to memorize the stars they needed to guide them home. It was also a site for religious ceremonies, a launching point for fishing expeditions, and home to a small population. But in the 1700s, everything changed. Intertribal conflict on Kaho‘olawe killed most of the island’s residents, leaving it depopulated. When haole (non-Native Hawaiians) began arriving at the end of the century, they introduced goats, cows and sheep — and cats, which were used to control rodents.

Kaho‘olawe had always been dry, and with no native mammals, its vegetation fell victim to the invasive grazers. As the animals ate, the island began to erode away, such that passing ships would avoid Kaho‘olawe to prevent being coated by a persistent cloud of iron-tinged red dust that blew from its surface.

Then, in 1941, Japanese warplanes dropped bombs on Pearl Harbor. The U.S. military declared martial law across Hawai‘i, and took over the dusty red hillocks of Kaho‘olawe as a training ground for war. Ships practiced peppering the shoreline with gunfire, and submarines developed attack plans by firing torpedoes at its looming cliffs. Warplanes ran bombing runs from above, while on land, the military exploded grenades and mortars, fired rockets, and even burned napalm.

By some accounts, locals believed that Kaho‘olawe would be returned to them after the war ended, but the military occupation continued for decades. So, in 1976, inspired in part by Native American protests and occupations in the continental US, a group of Indigenous Hawaiians sailed across the channel from Maui and occupied the island. The group, called Protect Kaho‘olawe ‘Ohana (PKO), simultaneously filed a suit in federal court asking for an end to bombing on the island, in line with the National Environmental Policy Act of 1969.

It would take years of labor, negotiation and personal loss, including the deaths of two PKO members who disappeared on a boat ride to the island, before the restoration of Kaho‘olawe finally began: first through an agreement that the Navy would clean up the island after each test, and by 1994, a bill that stopped military action altogether and started the process of returning the island to its people.

Looking northeast towards Maui from Pu'u Moa'ulani, the highest peak on Kaho'olawe, with a rain ko'a — a shrine built to encourage rainfall — in the foreground.
Looking northeast towards Maui from Pu’u Moa’ulani, the highest peak on Kaho’olawe, with a rain ko’a — a shrine built to encourage rainfall — in the foreground. Image by Momi Wheeler/Protect Kaho’olawe Ohana.

Toward a full restoration

Between 1994 and 2004, the U.S. military went to work removing unexploded ordnances, what it calls UXO, from Kaho‘olawe. This work utterly transformed access to the island. Today, there’s a shoreline base camp where volunteers and visitors can spend the weekend, and several sites on the island that regularly host ceremonies. But access isn’t unlimited. The military cleanup removed surface ordnance from 68% of the island. Only 9% of the island was cleaned down to a depth of 1.2 meters (4 feet), and 30% — mainly dangerous and difficult-to-access places like gullies and cliffs — hasn’t been cleared at all. There are places where bombs are still emerging from the blowing red dirt.

This remaining UXO is a barrier to completing the restoration of Kaho‘olawe, especially because the same restrictions don’t apply to the island’s invaders.

As on much of the Hawaiian Islands today, invasive species run rampant on Kaho‘olawe. In addition to cats, introduced buffelgrass (Cenchrus ciliaris) and fireweed (Senecio madagascariensis) still outcompete native grasslands. Thorny kiawe (Prosopis pallida), a type of mesquite, sucks up already-limited freshwater. Mice like to chow down on native seeds, and along with a small population of rats, are known to snack on seabird eggs. The military removed the goats during their cleanup in the ’90s.

Still, it’s primarily cats that are keeping native Hawaiian seabirds away. But removing them has proved a nearly impossible task in landscapes peppered with bombs.

That’s where Sentinel could come in. There’s no cell service on Kaho‘olawe, so previously a person would need to physically hike to reach camera traps, which required hiring a UXO expert for any trip to uncleared areas. Enter Conservation X Labs, which developed a drone payload that can act as a “data mule,” flying out to the camera trap to download any images and bring them back, knocking human labor down to a single trip to place the camera traps.

Photo detection of a cat retreived by Sentinel data mule on Kaho'olawe.
Photo detection of a cat retreived by Sentinel data mule on Kaho’olawe. Image courtesy of Island Conservation.

Next, Conservation X Labs created an onboard computer system that uses AI to recognize cats in the camera trap’s motion-triggered images. When the drone returns with the downloaded data, the humans on the other end are saved the trouble of having to sort through “8,000 photos of grass moving” to find a cat, as Sullivan puts it.

With a network of camera traps arranged on the island, the Kaho‘olawe Island Reserve Commission (KIRC), which manages the island’s restoration, will be able to more accurately estimate the cats’ abundance and where they’re most densely situated — data that can guide efforts to trap them. And when the eradication effort begins, the camera traps will be especially helpful in the excruciating and often costly process of what’s called “confirming zero,” i.e. that there really are no more cats left.

“It’s obscene how much money it costs to prove you did your job correctly,” Sullivan laughs.

Tests on Kaho‘olawe have proved that the Sentinel system would work. In fact, the tests were so successful that Island Conservation used the data from Hawai‘i to run another test on Floreana Island, in the Galápagos, which has developed into a full-fledged cat eradication program.

But on Kaho‘olawe, the plan is currently on hold. While there are still camera traps on the island gathering data, KIRC isn’t currently utilizing Sentinel due to a lack of funding. Because it will take time to gather population data once this program is funded, actually removing the cats remains over the horizon.

“We always tell people the [return of] Kaho‘olawe [to Hawaiians] was due to the lucky confluence of the right political conditions in Hawai‘i and in the federal government,” says Michael Nahoopii, the executive director of KIRC.

As a section of the state’s Department of Land and Natural Resources, KIRC and its partners, like Island Conservation, must choose their activities based on the government funding that’s available. For instance, right now the state is heavily funding coastal restoration, so KIRC is focusing on restoring wetlands and stabilizing sand dunes to face sea level rise.

When it comes to the cat project, it’s just waiting for the wind to change.

“One of these days if [the funding is available] to eradicate cats and restore seabirds, we’ll go for it,” Nahoopii says.

Sentinel pairs AI-powered camera traps with a remotely operated drone, allowing researchers to collect data on the island’s invasive cats remotely and minimizing the need for travel.
Sentinel pairs AI-powered camera traps with a remotely operated drone, allowing researchers to collect data on the island’s invasive cats remotely and minimizing the need for travel. Image courtesy of Island Conservation.

‘It’s a cultural park’

Kaho‘olawe today looks very different from how it did the day that historian Davianna Pōmaikaʻi McGregor first set foot on its shores. On that day in 1985, the island was nearly barren; goats had grazed down any vegetation they could reach, leaving behind only thorny kiawe. No birds sang.

“You could feel the pain that the island was experiencing,” McGregor remembers.

Today, the island’s bare top is filling in with native waving golden pili grass (Heteropogon contortus) and yellow-flowered Hawaiian cotton (Gossypium tomentosum). There are more wiliwili trees (Erythrina sandwicensis) blooming orange in the spring, and ‘a‘ali‘i shrubs (Dodonaea viscosa) along the coast drawing in native koa bugs (Coleotichus blackburniae) and Hawaiian blue butterflies (Udara blackburni). Native birds are beginning to find new roosts: McGregor has heard stories about nesting albatross (Phoebastria spp.) along the coast, and one fateful evening, Sullivan himself witnessed a group of some 20 pueo, Hawaiian short-eared owls (Asio flammeus sandwichensis), thronging in the sunset sky.

On many weekends, the island also once again hosts the sounds of chanting and laughter, music, and the swish of hula as Hawaiians themselves return.

“You get that feeling there of how our ancestors might have experienced the islands,” McGregor says. “You can pattern your life on nature, with the rising and setting of the sun. You’re in the elements, and there are the sites our kupuna [ancestors] left for us. It’s like they just left yesterday — they’re gonna come back, they just went to visit.”

Nāmakapili, a traditionally-constructed hale pili (a structure made with pili grass) built on Kaho'olawe for ceremonies.
Nāmakapili, a traditionally-constructed hale pili (a structure made with pili grass) built on Kaho’olawe for ceremonies. Image by Momi Wheeler/Protect Kaho’olawe Ohana.
Looking west across landscapes of Kaho'olawe from Pu'u Moa'ulani, the highest peak on the island.
Looking west across landscapes of Kaho’olawe from Pu’u Moa’ulani, the highest peak on the island. Image by Momi Wheeler/Protect Kaho’olawe Ohana.

It is this final piece, the connection between people and ecosystem, that Kaho‘olawe advocates stress when they talk about restoration. Each part of the island’s missing ecosystem supports not only its native ecology, but the cultural practices so important to Indigenous Hawaiians. For example, removing invasive kiawe would make more freshwater available to grow plants used to make traditional cloth and to farm taro (Colocasia esculenta), locally called kalo, to feed people. Likewise, removing cats and returning native seabirds, which are similarly dependent on native vegetation, would also mean the return of their guano, which provides nutrients to coastal habitats and nearby coral reefs, bolstering the rich traditions of fishing that for centuries launched from these shores.

“It’s not a national park, it’s a cultural park,” Nahoopii says. “We want to create the habitat and the environmental conditions that support Native Hawaiian cultural practices, where they can be reintroduced and can thrive.”

The final big step for Kaho‘olawe will be for the Hawaiian people to return it, legally. At present, the island is held in trust by the state, until a sovereign entity exists that can take over its ownership, as Indigenous Hawaiians don’t have any state or federally recognized organized governance. However, Nahoopii says Hawaiians themselves disagree on the form that this should take, whether as tribal governments like Native American tribes in the continental U.S., corporations like Alaskan First Nations, or even a Hawaiian state within the state.

“That’s up to the rest of the people of Hawai‘i, when they tell us they’re ready,” Nahoopii says.

There’s still much to do. But Kaho‘olawe has always been a place of change. The island is also known as Kanaloa, the same name as the deity of the ocean and of long-distance voyaging, as well as Kohe Malamalama a Kanaloa, the shining birth canal of Kanaloa — a place where new things are born. When speaking of the island, a common refrain is Kūkulu Ke Ea A Kanaloa: the life and spirit of Kanaloa builds and takes form. In that mindset, the process of planting and planning, of seeking out funding, of finding agreement among a people, may feel less like delay and more like building: a process of becoming as the island finds its next form.

Banner image: A red-tailed tropicbird (Phaethon rubricauda), one of the seabirds found on Kaho‘olawe. Image by Meghan Cassidy via Wikimedia Commons (CC BY-SA 4.0).

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