Draft Environmental Assessment - Possible Management Actions to Save the Po`ouli

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Po`ouli

(Melamprosops phaeosoma)

Description

The Po`ouli (Melamprosops phaeosoma) is one of five endangered Hawaiian honeycreepers that inhabit the rainforests of east Maui. The Po`ouli is a stocky bird, about 5 1 /2 inches long, whose Hawaiian name means "black face," referring to its dark facial feathers. The cheeks and breast feathers are white, turning a light red-brown toward the posterior. The top of the head is greyish, turning to dark brown on the back. The Po`ouli was discovered in 1973 by three University of Hawaii students while they conducted field work in the Hana rainforest. Molecular studies indicate that the Po`ouli belongs to an ancient lineage of honeycreepers. It is so unique in its form and behavior that it has been placed in its own genus, Melamprosops.

Habitat

Although fossil remains have been found on the dry south slope of Haleakala, indicating that the Po`ouli was previously more widespread, it is currently restricted to the upper elevations of east Maui's rainforests, from 4,650- 6,680 feet. All of the known birds occur within the Hanawi Natural Area Reserve and adjacent portions of Haleakala National Park and the Ko`olau Forest Reserve. These areas receive an average of 350 inches of rain annually. The terrain is steep and thickly vegetated. While some alien weeds are present, the area is dominated by native Hawaiian plants such as the `ohi`a tree and `olapa.

Life History

The Po`ouli is a secretive bird that spends a great deal of its time in the native understory and brush of the rainforest, making it difficult to detect and observe. It gleans leaves and bark in search of the insects, spiders, and small snails upon which it feeds. The few nests that have been observed contained 1-2 chicks during the months of April-June. These nests were built of twigs and mosses and were located in leafy branches of `ohi`a trees. Po`ouli commonly forage with small groups of other Hawaiian forest birds such as the endangered Maui Parrotbill and more common species such as the Maui Creeper or `alauahio.

Threats

When first discovered in 1973, the total population of Po`ouli was felt to be fewer than 200 birds. Popula- tions of so few individuals are extremely vulnerable to any threat, especially when they are restricted to such a limited area. Unfortu- nately, the threats to these and other Hawaiian forest birds are not few. Almost all native forest birds are restricted to elevations above 4,900 feet. Possibly one of the most telling explanations for this restricted distribution is that introduced mosquitos, which transmit avian malaria, are common below this elevation. Avian diseases such as malaria and pox virus were probably one of the most critical reasons for the devastating declines of perching birds in Hawai`i during the 1980s.

Destruction of habitat by pigs, goats, and other introduced ungulates has had devastating impacts on all native habitats in Hawai`i. Feral pigs have had direct impacts on native forest birds by destroying understory vegetation, spreading alien weeds, and creating mosquito breeding areas from their rooting and wallowing in wet forests. For birds such as the Po`ouli, which specialize in foraging in the understory, disturbance by pigs has been a major threat. Introduced predators such as the black and Polynesian rat, the small Indian mongoose, and the feral house cat are all known to be predators of Hawai`i's native birds. The great abundance of black rats in most Hawaiian forests, as well as their tree-dwelling habit, indicate they may be a primary threat to the Po`ouli.

Introduced forest birds have over the years encroached into the habitats utilized by the Po`ouli and other native forest birds. These alien species often harbor and spread introduced diseases, and compete for food and nest sites with the native Hawaiian species. The very small population size of the Po`ouli compounds all of these threats and makes them more vulnerable to naturally occurring disasters. In addition, small populations typically show the negative effects of inbreeding, such as smaller clutch size and lowered resistance to disease. It has been shown that individuals of a given species that are derived from very small populations do not survive as well as individuals that exist in large populations.

Current Status

The Po`ouli is now believed to number only three individuals. These birds exist in three distinct home ranges and do not appear to interact with one another. Scientists believe these birds are made up of one male and two females, and that there may be a chance to save this species if appropriate action is taken now. The Hawai`i Department of Land and Natural Resources and U.S. Fish and Wildlife Service are currently seeking public input on what the appropriate action should be.

Did You Know . . .
  • The east Maui rainforest contains more species of endangered forest birds than anywhere else in the State?
  • The Po`ouli is the only Hawaiian forest bird known to consume tree snails?
  • The Po`ouli seldom calls or sings and typically is seen before it is heard?

See also,

  • Map of Po`ouli Home Range
  • Other East Maui Forest Birds
  • Draft Environmental Assessment - Possible Management Actions to Save the Po`ouli

    Division of Forestry and
Wildlife