Species Profile: Palila

The Finch-billed Honeycreeper

Palila. Photo: Peter LaTourrette/ birdphotography.com

When the Palila's whistle-like call echoed throughout the forests of Hawaii, early Hawaiians believed it was a sign of impending rain. Today, this distinctive call is only heard in the dry, subalpine forests on the slopes of Mauna Kea, the highest volcano on the Hawaiian Islands. The Palila has been extirpated from 90 percent of its historical range, which once included the slopes of the Mauna Loa and Hualalei volcanoes.

The Palila is one of the few surviving members of the Hawaiian honeycreeper family, a diverse group of birds that evolved from a single ancestral species. Most of the other Hawaiian honeycreepers are now extinct due to introduced diseases, such as avian malaria and pox, invasive plants and animals, and habitat loss.

This handsome bird has gold, gray, and white plumage and a heavy, finch-like bill, adapted specifically for feeding on the seed pods of the mamane, a native tree of the dry forest. Palila wander up and down the slopes, following the mamane seed crop as it ripens. The birds also feed on mamane flowers, buds, and young leaves, as well as berries, caterpillars and other insects. The availability of mamane seeds has a significant effect on adult survival and reproductive success; in drought years with few mamane seeds, most Palilas do not even attempt to breed.

Sheep and goats imported by early European settlers quickly denuded mamane forests, destroying much of the Palila’s habitat. By the time the species was listed as Endangered in 1967, only a few thousand individuals remained. In 1977, Critical Habitat was designated on Mauna Kea by the U.S. Fish and Wildlife Service. The following year, a federal court ruling required all feral sheep and goats to be removed from Palila habitat. There have been several legal challenges to the ruling since that time, and unfortunately, some sheep still remain on Mauna Kea. Annual surveys of Palila began soon after initial ungulate removal efforts; since then, the population has stabilized at around 3,000 birds.

In 1996, staff at the San Diego Zoo began a captive breeding program with eggs harvested from wild Palila nests. By 2003, enough birds existed in captivity to begin reintroductions. Fifteen captive-reared birds were released into the wild that year, and at least seven remained in the reintroduction area for at least a year. In July 2005, one of those captive-bred birds was observed feeding two fledglings—the first proof that the captive-raised birds had bred.

Wild Palila have also been translocated to suitable habitat within their historic range. By the end of 2005, U.S. Geological Survey biologists had moved 160 birds from western Mauna Kea to the northern slope. Over half these birds returned to the area where they were first captured, but a small colony of approximately 25 birds remained on the north slope, and is now breeding there. Palila have also been observed moving between the north and west slopes on their own. An additional 28 birds were translocated in 2006; conservationists are hopeful that this positive trend will continue.

Unfortunately, other threats to the Palila still remain. Invasive plants, wildfires, and other feral animals such as cats, rats, and mongoose that prey on Palila chicks, still jeopardize the species. Recent successes with the captive breeding and translocation programs may signal a brighter future ahead for the Palila, but like many of Hawaii’s endemic birds, continued intensive management is likely to be needed for many more years, perhaps forever if the species is to survive.