Editor’s note: This is the second of a two-part series on Hawaii Volcanoes National Park. The first story detailed the Puu Loa petroglyphs and the use of pack animals in the park. This story continues the park’s narrative with a look at the endangered nene goose.
HAWAII VOLCANOES NATIONAL PARK — The carved stone image of rider and horse — standing impassive for unknowable years — has also seen the expansion of the nene, the Hawaiian goose.
Before conservation efforts, there were 30 living nene and the species dangled on the brink of extinction. Careful breeding, environmental improvements and other efforts beginning in the 1950s have brought that number up to 2,500 birds statewide. More than 250 live in the park, where care of the species is led by Kathleen Misajon, the park’s Nene Recovery Program manager.
The conservation efforts are continual, said Misajon, and may remain necessary for the foreseeable future. The habitat has been so thoroughly disrupted and there are so many new threats that extinction is a constant risk, she said.
To protect the birds, teams fence in nesting sites to keep out the numerous introduced predators — dogs, feral cats, mongooses, pigs and rats, to name the most prominent ones.
Being birds, they have no trouble flying into the site and don’t seem to mind the change in their environment, she said.
Those fences also help protect endangered natural areas, said Rhonda Loh, chief of natural resources management. The unprotected side of the special ecological area around Thurston Lava Tube still shows limited growth and stagnant water, even after the extensive control of feral pigs by the state.
Fencing out the pigs
The pigs are one of the most destructive animals the fences stop. Originally introduced by Hawaiians, they spread out after the introduction of Europeans, according to Linda M. Cuddihy and Charles P. Stone’s study on “Alteration of Native Hawaiian Vegetation.”
“Feral pig damage to native vegetation has reached extreme levels…,” they wrote.
They said the animals spread alien seeds, kill native plants, make areas unsafe for native growth and tear up the rainforest floor. One area not discussed is death of animals. Misajon said she has come back to nesting sites to find nothing left but a few feathers and pig tracks.
In the cloud forest near the lava tube, the damage includes gutting the tree ferns. Loh said the animals will come in, knock down the plant and gut it. This leaves standing water for mosquitoes to breed in and ruins it as a “nurse log,” where the decay allows new trees to begin growing.
There are more than 20 of the fenced-off areas around the park, where crews practice “landscape level control.” Every two to five years they go through and suppress the weeds as best they can, Loh said.
These areas are selected because of their ecological uniqueness and being the closest to their native settings. They form one potential haven for the adaptable nene, which has changed and survived where other native geese and ducks have gone extinct, said Misajon.
That adaptability includes flight, the ability to digest the alien grasses that displaced their native foods and moving where they nest. The birds prefer to keep the same nesting sites, she said, but some of those introduced in the more dangerous lowlands moved mauka.
There were at least two geese species and four duck species in prehistoric times that went extinct, although researchers are discovering new specimens that may be other species. Many were flightless, as flying was a trait unnecessary for survival in a land before the arrival of predators.
The nene was one of the few to continue to use its wings for flight, despite the myth that they are poor flyers, said Misajon. They’re big birds and people rarely see them take off, which leads to people assuming they are subpar aviators.
That’s been disproved, as they have flown from island to island, sometimes expanding their range outside of what the conservationists expected.
“They’re not quick to fly,” she said, “unless they are going somewhere.”
It’s only one of the misconceptions about the bird. Early naturalists considered them “mountain geese,” as they only lived on the upper sections of the islands. But that was an adaptation, Misajon said, with the birds avoiding the more dangerous lowlands. Now with safer terrain, they are expanding, she said.
The upcoming drought has her concerned. The last severe drought savaged the species, leading to the death of half the animals. She’s hoping they manage to gather enough energy in the next few months to both breed and survive the harsh conditions.
The concerns are such that the park is considering putting out fodder for the birds, said Loh.
