The ancestors of Hawai‘i’s native land snails came here millions of years ago via winged migration—they hitched rides on the feet and feathers of seagoing birds. Before the arrival of humans, there were more than 750 species of endemic land snails in Hawai‘i. About forty-two of those species were Achatinella, which exist only on O‘ahu. Partulina, a related genus in the family Achatinellidae, is found on Maui, Moloka‘i, Lana‘i and Hawai‘i Island.
|Snail savior: Biologist Michael Hadfield searches an 'ohi'a tree in the Honouliuli Forest Reserve for a critically endangered native land snail. Once abundant in O'ahu's forests, the sensitive and slow-growing kahuli have suffered from habitat loss, predation and a nineteenth-century mania for shell collecting. Through a captive breeding program at the University of Hawai'i at Manoa, Hadfield hopes to re-establish kahuli in the wild.|
Today it is illegal to take live snails or their shells from the wild. In the past, however, kahuli were an important part of native culture: Making kahuli shell lei was a Hawaiian tradition, and prized kahuli lei heirlooms are still passed down within families. Kahuli are also known in chants and legends, sometimes referred to as pupu kani oe, or “singing snails.” The name of King Kamehameha III’s summer cottage in Nu‘uanu is Kaniakapupu, or “song of the land snail,” so called because the area was once a rich habitat for kahuli (today it’s mostly a bamboo forest, and the snails are gone). There’s much debate about whether snails can actually sing; so far there’s no scientific evidence that snails vocalize. One explanation is that the chirping of crickets was attributed to the snails, as both are active at night.
Perhaps more important than whether the snails actually sing is the phrase itself, which reflects a Hawaiian relationship with the ‘aina (land). Biologist and Hawaiian cultural practitioner Samuel M. ‘Ohukani- ‘ohi‘a Gon III cites a love chant about the goddess La‘ieikawai in which the singing of the snails is a sign that the bride and groom should meet:
O ka leo o ke kahuli
Aia i ke kuahiwi
O ka pupu kani oe.
(The voice of the snail
There in the uplands
It’s the singing shell.)
“Hawaiians give intimate attention to even the smallest signs seen or heard in the landscape,” explains Gon, “and accord these great significance, as in the name of a chiefly residence or the single most important sign that a goddess should be betrothed.”
In the mid-nineteenth century kahuli snails caught the fancy of European collectors who succumbed to “shell fever” of epic proportions. Descendants of missionaries and other kama‘aina residents scooped them up by the hundreds of thousands. They paid Hawaiians to fill containers with snails and pack them out on horseback. Hawaiian tree snails, like many other flora and fauna of the period, fell victim to a Victorian-era passion for collecting souvenirs. That only a few collectors kept accurate records is a tragedy: Volumes of data were lost because collections were often a hodgepodge of snails from many sites.
Collecting was only one factor, though, in the kahuli’s disappearance. Development, logging, wildfires and the introduction of exotic plants shrank native forests. Two introduced predators also took a toll: the rat and the rosy wolf snail. The state Department of Agriculture deliberately introduced wolf snails in 1955 as biocontrol against giant African snails, also introduced, that had become a serious yard and garden pest. But the wolf snail isn’t picky; it eats almost any snail, even other wolf snails. It devours the defenseless kahuli, leaving an empty shell. If that weren’t problem enough, it’s been recently discovered that alien Jackson’s chameleons also gobble up kahuli, shells and all. And so the kahuli, once superabundant in the forests of O‘ahu, rapidly declined. Today more than 75 percent of all of Hawai‘i’s native land snails are extinct. At least half the species of Partulina are extinct, and only ten Achatinella species remain. All are critically endangered and federally protected.