Drone Reveals 'Extinct' Hawaiian Flower Growing on Remote Cliff

The native Hawaiian plant Hibiscadelphus woodii flowers on a remote cliff in Kalalau Valley on the island of Kauai. Ken Wood/National Tropical Botanical Garden

Hawaii is known as the "extinction capital of the world," a reference to the dramatic loss of the islands' native wildlife, largely due to invasive species and habitat degradation. As these unique plants and animals fade away, however, researchers in Hawaii have found at least a glimmer of good news: One species that was declared extinct seems to still exist, albeit barely.

The species — Hibiscadelphus woodii, a flowering plant related to hibiscus — was discovered in 1991 by botanists from the National Tropical Botanical Garden (NTBG), who found four individuals growing from a sheer cliff in Kalalau Valley on the island of Kauai. The plant grows as a shrub or small tree, producing vivid yellow flowers that become purple or maroon as they age. Its nectar-rich blossoms are probably pollinated by native honeycreeper birds, according to the NTBG, including the amakihi.

Those four shrubs were the only known members of their species, which is thought to be endemic to Kauai. At the time, their discovery made H. woodii the seventh species in the genus Hibiscadelphus, all of which exist only in the Hawaiian Islands. (An eighth species, H. stellatus, was later discovered on Maui in 2012.) Ominously, however, five of the other Hibiscadelphus species were already deemed extinct in the wild by the time H. woodii was officially named in 1995.

Researchers knew this tiny colony of H. woodii could be next, due to threats from invasive plants and animals as well as rock slides, yet every effort to propagate the plants failed. Three of the four known individuals were crushed by a falling boulder in the late 1990s, and although the fourth survived until at least 2009, it was found dead two years later. In 2016, the species was formally declared extinct by the International Union for Conservation of Nature.

Then, while piloting a drone through the Kalalau Valley in January 2019, NTBG drone specialist Ben Nyberg caught an image that stood out. The plant wasn't flowering at the time, but it resembled H. woodii enough to warrant another look. When Nyberg sent the drone back to take more photos in February, it revealed a trio of H. woodii plants growing from the side of a steep cliff.

For a sense of how steep and remote the location is, see the video below from the NTBG. The clip opens with sweeping views of the Kalalau Valley landscape before zooming in to the newfound colony of H. woodii:

This is good news, since it means the species isn't extinct after all, but such a small colony of plants is still vulnerable — as that boulder demonstrated three decades ago. And while their dangerously steep location may offer protection from some threats, like careless people or hungry goats, it has also prevented researchers from traveling to the site.

"We've looked at possibly short hauling somebody to go in there, but the cliff section is so vertical and it's so far down the cliff that we're not sure that there would be enough space for a helicopter to fit there," Nyberg tells National Geographic. "It would be very difficult and dangerous for someone to even get to the top of the cliff to rappel down to it."

But maybe people don't need to physically visit the site. Drones already helped track down this lost species, and as National Geographic reports, researchers are now considering a drone that's equipped to collect cuttings from plants. Technology like that could be a game-changer for conservation in hard-to-reach places like the Kalalau Valley, a biodiversity hotspot and home to more than 50 endangered species of plants. As an extinction crisis spreads in Hawaii and around the planet, drones can help scientists monitor vulnerable species and discover new ones — or even rediscover old ones — before it really is too late.

"Drones are unlocking a treasure trove of unexplored cliff habitat," Nyberg says in a statement, "and while this may be the first discovery of its kind, I am sure it won't be the last."