A rare finch-billed honeycreeper that once occurred across the island of Hawai'i has been identified as one of the country's most isolated species.
Although the six-inch Palila was one of the first species to be federally listed under the Endangered Species Act in 1967, nearly five decades later it is still struggling. In a report published this week, the Endangered Species Coalition declared the bird one of 10 rare species in the United States that lack safe, navigable corridors to connect them to important additional habitat or other populations.
Habitat loss and conversion, dams, roads, and other developments are among the leading causes of wildlife habitat fragmentation, according to the report, “No Room to Roam: 10 American Species in Need of Connectivity and Corridors.” See the report.
Native Hawaiians once thought the Palila's beautiful, liquid song was a sign of rain. Now the distinctive sound is rarely heard. Although the birds once lived on O'ahu and Kaua'i, today they are only found in a tiny patch of habitat on the Big Island: about 25 square miles on the upper slopes of Mauna Kea Volcano. Roughly 2,000 birds remain in this area, which represents less than 5 percent of the species' historical range.
This bird depends on the mamane tree as its primary source of food. Like the Palila, the mamane tree is a species native to Hawai'i that is found nowhere else. The bird moves up, down, and around the mountain to find sufficient seed pods at just the right stage of ripeness to eat. Its hooked bill is just right for opening the mamane's tough, fibrous seed pods.
Non-native sheep and other hoofed mammals are a tremendous threat to all the native plants of Hawai'i. Sheep, goats, and cattle destroyed lots of habitat originally, and sheep continue to degrade the forest on Mauna Kea through browsing on mamane saplings and trees. This loss of other potential feeding and breeding areas has isolated Palila, and made them more susceptible to extinction.
Members of the Endangered Species Coalition nominated a range of wildlife species for consideration. A committee of scientists reviewed the nominations and decided which species were most in need of additional connections and corridors; finalists were included in the report. The report also includes everyday actions that people can take to help promote habitat connectivity, such as urging land management agencies to protect important wildlife corridors and supporting efforts to add wildlife crossings to roadways.
Bringing back populations of the Palila is one of the top priorities of American Bird Conservancy's Hawai'i Program. ABC nominated the Palila for the Coalition's list because although scientists know which management actions are required to protect the species, there are insufficient resources to put them into practice.
“ABC is working with the State of Hawai'i's Division of Forestry and Wildlife and the Mauna Kea Forest Restoration project to restore the Palila's native mamane forest and protect the bird's nesting habitat from non-native predators,” Farmer said. “However, the sheep remaining in the Palila's legally designated critical habitat on Mauna Kea need to be removed as soon as possible, so that forest restoration and regeneration can be accelerated, and the Palila's recovery can begin.”
Installation of predator-proof fencing is one of the ways ABC and partners work to reduce the impact of non-native predators in the Hawaiian islands.
According to the report, the Florida panther numbers less than 200 adult individuals, yet a record 25 of these cats were killed crossing roads in 2014 alone. Vehicle collisions are also taking a toll two other species featured in the report: the California tiger salamander and the spotted turtle.
The prehistoric pallid sturgeon once swam the entire length of the Missouri River system from Montana to New Orleans, but the population has dwindled to a few hundred fish as its upstream migration to spawning areas is blocked by dams on the Missouri and Yellowstone Rivers. The migration route of the Chinook salmon of the Pacific Northwest (a species that received an honorable mention in the report) is also impeded by dams.
Other species featured in the report include the Karner blue butterfly, the Lesser Prairie-Chicken, the Yellowstone grizzly bear, the eastern prairie fringed orchid, and the Mexican gray wolf.
“Habitat loss and fragmentation are the biggest drivers of species decline and extinction,” said Leda Huta, executive director of the Endangered Species Coalition.
“Fortunately, there are actions that wildlife management agencies and the public can take to better connect these species. We owe it to our future generations of Americans to protect the special places that wildlife need to survive and migrate.”