On December 10, 2024, the released endangered O鈥榓hu tree snails into an exclosure in the Honolulu Watershed Forest Service of the Ko鈥榦lau Mountains on O鈥榓hu. The Achatinella fuscobasis have been extinct in the wild since 1991, and their reintroduction marks the culmination of a nearly half century of partnerships, research, and conservation work.
Since the 1970s, the bet365下载ios has supported snail protection and recovery, especially in partnership with Hawai驶i DLNR, the University of Hawai鈥榠 and the U.S. Army. While conservation has been slow, it certainly hasn鈥檛 been sluggish. When it comes to saving an endangered species, even our best work may take generations.
O驶ahu Tree Snails: A Jewel of the Forest
Hawaiian 办腻丑耻濒颈, or tree snails, have been described as jewels of the forest and have been depicted as being able to sing according to Hawaiian folklore. They have beautiful multicolored shells, and are often described in traditional Hawaiian poetry, hula, lei, and chants. Native snails also play an important role in the Hawaiian ecosystem by feeding on fungus and algae that grow on plant surfaces and by contributing to nutrient cycling in forests.
There were once more than 750 species of 办腻丑耻濒颈 in Hawai驶i. Within the last century at least 60% of those snails have gone extinct. There are 44 Hawaiian snail species listed as endangered under the Endangered Species Act and many more unlisted species that face serious threats. Much of this extinction crisis can be attributed to non-native predators.
The Pacific rat, arrived in Hawai驶i nearly 1,000 years ago on the canoes of Polynesian explorers. Two more types of rats, the roof rat and wharf rat, arrived from European ports hundreds of years later. As omnivores, rats consume everything from plants and seabird eggs to garbage. In the years since their introduction, rats a have become one of the in the Hawaiian islands, and have contributed to the destruction of many native plant and animal species, including snails.
In the 1930s, the giant African snail arrived in Hawai驶i as a . The snail is considered to be the , and has had a heavy impact on tropical and subtropical regions. While the giant African snail is mostly known in Hawai驶i for being a garden pest, its presence spurred land managers to introduce the cannibalistic to help with population control. However, in addition to preying on giant African snails, the rosy wolfsnail became terribly efficient at destroying native snail populations.
鈥淲hat we found in the mountains is we鈥檇 often have a nice robust population of Hawaiian tree snails,鈥 said , emeritus professor of biology at the University of Hawai驶i at M腻noa. 鈥淪uddenly it would crash and what we would find is just their beautiful shells. The rosywolf snail doesn鈥檛 eat the shells, it simply shoots a big proboscis inside the shell and pulls the snail out and swallows it. Rats do crunch up the shells. So you can always tell who鈥檚 preying on who when you get there.鈥
(Read or listen to a full interview with Dr. Hadfield, below)
Hadfield is considered a pioneer in Hawaiian tree snail conservation, a part of the first generation of researchers who raised the alarm about the snails鈥 imminent extinction. In the 1970s, Hadfield and his students meticulously documented their biology, lifecycles and reproductive capabilities, and their precipitous decline. Since Hadfield started his work, rats, non-native snails, and other predators such as Jackson鈥檚 chameleons and the New Guinea flatworm have decimated native snail populations that were once abundant.
鈥淭here is no evidence that the Hawaiian tree snail had any predators during their evolutionary period,鈥 Hadfield said. 鈥淚f you read descriptions of the snails in the late 1880s or early 1900s, they talk about them hanging from the trees like clusters of grapes.鈥
Captive Propagation: Growing Snails in the Lab
In 1981, the bet365下载ios listed multiple species of the O驶ahu tree snail as endangered under the Endangered Species Act. Ten years later, Hadfield collected 11 of the last A. fuscobasis species of snails in the wild and began an experimental program to breed them in a lab. It was a final, high stakes effort to save this important species.
鈥淭he first one was a thing that looks exactly like your home refrigerator, except you could set day and night cycles of light inside, and also set temperature cycles,鈥 Hadfield said. 鈥淲e knew that the snails were activated by water, so we had to poke holes in the walls of our environmental chambers and plumb them so we could put in sprinklers.鈥
Because snails feed on molds that grow on the surface of leaves, Hadfield and his students climbed into the mountains at least every other week and brought a big bag of fresh leafy branches of . However, instead of growing the mold directly on the leaves, they had more success cultivating the mold in petri dishes in their lab.
鈥淵ou could sort of scoop it out of the petri dishes, and it would stick to the walls of the terraria and the snails ate it off,鈥 Hadfield said. 鈥淭hey loved it.鈥
Hadfield later built exclosures, or outdoor pens, to protect snails outside in their native habitat. The first exclosure Hadfield and his colleagues built was primitive, but effective. It was an electric fence about four feet tall and 4,000 square feet, with barbed wire at the top, mostly to keep out the human type of animals. A trough of salt around the perimeter was added specifically to keep out the Rosy Wolf snail. The scientists immediately observed that the snails outside the exclosure disappeared, but the snail population inside continued to thrive.
While the exclosure program started with Hadfield and the University of Hawai驶i, today it鈥檚 being managed by a second generation of snail conservationists and one of Hadfield鈥檚 students: David Sischo, who works for Hawai驶i DLNR. The exclosures Sischo manages are far more advanced. Nicknamed 鈥渒腻hili k墨puka鈥 -- an homage to the Hawaiian name for small islands of vegetation surrounded by lava flow -- the exclosures are about the size of a house and have slippery, solid wall sides and electrical barriers.
鈥淢ost people imagine that the rosywolf snail is going to go flying off smoking,鈥 Sischo said. 鈥淭hat鈥檚 not the case. It鈥檚 low voltage and just irritates them so they just kind of suck back into their shells and fall off the wall. It doesn鈥檛 kill them.鈥
Sischo intended to reintroduce the tree snails to the exclosures in late 2023, but he and his colleagues discovered that another nonnative species, Jackson鈥檚 chameleons, had infiltrated the barrier. The delay in reintroduction is emblematic of the challenges Sischo and his colleagues) are facing: without somehow neutralizing the predators on the landscape, the snails don鈥檛 have a chance of surviving in the wild.
"Conservation Needs to Happen From the Ground Up"
The ESA played a critical role in halting the 办腻丑耻濒颈鈥檚 slide to extinction. With the listing of the snail in 1981, scientists and land managers suddenly had a means to apply for funding, mitigate threats and protect habitat. The listing of O驶ahu tree snails also meant that other species that share the same habitat could benefit from the same protections.
鈥淲e鈥檙e able to leverage the funding we get for listed species and apply it to all species that are equally imperiled,鈥 Sischo said. 鈥淭here are species that are alive today because of the Endangered Species Act.鈥
Sischo pointed out that the protection from the ESA isn鈥檛 enough to stave off the extinction crisis in the Hawaiian islands. For every species that receives protection under the ESA, there are many more that need protection.
鈥淭here are close to 100 snail species that may go extinct within the decade, many that we have that are already extinct in the wild, that are unlisted and not protected by the Endangered Species Act,鈥 Sischo said. 鈥淪o for the species that have been listed, it鈥檚 saved them, and for the ones that haven鈥檛 been listed, unfortunately they鈥檝e kind of dwindled away.鈥
Sischo runs DLNR鈥檚 Snail Extinction Prevention Program, or SEPP, which is a partnership between Hawai驶i DLNR, the Service, the University of Hawai驶i, the U.S. Army Natural Resources Program, and other conservation entities and landowners. SEPP鈥檚 goal is both straightforward and herculean: to prevent the extinction of rare and endangered snails through captive breeding and wildlife management.
Joy Browning is a wildlife biologist with the Service鈥檚 Pacific Islands Fish and Wildlife Office and has helped lead snail conservation efforts. Browning said that while their urgent goal is to make sure the snails are still around in five years, they are hoping the snails will be around much longer.
鈥淲e need everyone鈥檚 k艒kua (help) and 鈥榠ke (knowledge), because no one person, group or agency has the ability, land, and tools to prevent the extinction of the k腻huli,鈥 Browning said. 鈥Conservation needs to happen from the ground up. It requires us to seek knowledge from around us, work with others in different roles, and rely on their strengths to help preserve what we have.
As the implementing agency for the ESA, the Service oversees snail conservation efforts. The Service provides both technical support and funding to DLNR for snail recovery, including more than $2.5 million in competitive State Wildlife Grants. Funding from the Service has helped support the captive propagation program and release of the snails into the exclosures.
鈥淐ollaboration has been the only way we鈥檝e been able to accomplish as much as we have,鈥 Sischo said. 鈥淭he bet365下载ios has been instrumental to our efforts. They鈥檝e gone out of their way to help us get funding and get support that we need to get these units up and get the animals into captive rearing. It鈥檚 been a great partnership and I鈥檝e been really thankful for the bet365下载ios. The Army has been wonderful as well. They鈥檙e one of our biggest partners on O鈥榓hu.鈥
In addition to snails living in 办腻丑耻濒颈 k墨puka, snails will also be placed at the Bishop Museum in Honolulu and the Honolulu Zoo. While the goal for the next five years is to prevent extinction, there鈥檚 hope that advances in technology and predator control will allow for the reintroduction of 办腻丑耻濒颈 so the species can thrive in the wild again.
鈥淚 think the recovery of these species is not going to happen in my lifetime,鈥 Sischo said. 鈥淚t鈥檚 going to be a tag team effort. A generational effort. I think it鈥檚 going to require multiple generations of conservationists to accomplish our objectives to get these animal populations up and back out on the landscape.鈥