Birds on Hawaiian Island Vanishing Fast

Nearly all native forest birds on the Hawaiian Island of Kauai are in decline and are headed towards extinction, finds a new survey and assessment.

Climate change-induced warmer temperatures are increasing the spread of disease, especially avian malaria, and are the primary reason for the imminent collapse of the native forest bird community on Kauai (also spelled Kaua'i), according to the findings, which are published in the journal Science Advances.

The affected birds are all different species of Hawaiian honeycreepers, which descended from small finches that reached the Hawaiian Islands 5–7 million years ago and arose to populate the islands in many forms and beautiful colors. Evolving in the once nearly disease-free paradise, they developed no natural defenses for malaria and other mosquito-borne infections.

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"Hawaii's forest birds are unique, in that they are found nowhere else in the world, represent forms unlike any other bird species in the world, and from an evolutionary point of view, the adaptive radiation of the Hawaiian honeycreepers is one of the most famous examples of evolution in the world," Eben Paxton of the U.S. Geological Survey Pacific Island Ecosystems Research Center at Hawaii Volcanoes National Park, told Discovery News.

"For the native Hawaiians," he continued, "the loss of these birds would greatly impact the forests, removing key components of the forest ecosystem like pollination, seed dispersal and insect control."

Paxton and his team used long-term survey data on Kauai's native forest birds' current range to understand how the abundance and distribution of bird species on the island have changed over the last several decades. The researchers determined that six of seven such species are rapidly declining in abundance across their range. They are as follows: 'akeke'e, 'akikiki, 'anianiau, 'l'iwi, 'apapane, and Kaua'i 'amakihi.

The seventh, Kaua'i 'elepaio, does not seem to be impacted as much by disease. This bird, commonly known as a monarch flycatcher, comes from a lineage that colonized the Hawaiian Islands more recently than the Hawaiian honeycreepers did.

Kauai's high elevation forests traditionally were too cool for self-sustaining populations of mosquitoes that could spread disease.

"With global warming, the temperatures are increasing on the Hawaiian Islands, facilitating mosquitoes and the diseases they transmit to move into increasingly higher forest habitats," Paxton said.

A 2014 study published in the journal Global Change Biology shows that increasing average air temperatures, declining precipitation and other climate changes have taken place over the past 20 years on Kauai and "are creating environmental conditions throughout major portions of the Alaka'i Plateau that support increased transmission of avian malaria," wrote lead author Carter Atkinson and his colleagues. The Alaka'i Plateau refers to the primary upland forest region of Kauai.

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"What is happening on Kauai is truly tragic and does not bode well for other high elevation forest bird communities in the Hawaiian Islands that have been able to persist into this century," said Atkinson, also with the U.S. Geological Survey Pacific Island Ecosystems Research Center.

The new study, he said, "really is the nail in the coffin, so to speak, and will hopefully be a wake up call about how little time we have to make critical decisions about saving remaining native species in the islands."

Atkinson and his colleagues found that two birds in particular, 'akeke'e and 'akikiki, are experiencing dangerous population declines as a result of the changes.

Paxton and his team now estimate that 'akeke'e could go extinct in the wild by the year 2028 and 'akikiki by about 2046. Scientists have been rushing to collect some eggs from these highly endangered birds to establish a captive breeding population.

There are a number of steps that can be taken to save the colorful birds in their native habitat, but each comes with incredible challenges.

First, Paxton said, the disease cycle for avian malaria -- parasite to mosquito to bird -- needs to be broken. The most promising approach is by reducing mosquito populations, but Kauai's mountains are remote, roadless, rugged, and many areas unreachable. As a result, larval habitat reduction and localized pesticide spraying are impractical.

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Other approaches being considered are irradiated sterile male mosquito releases, introduction of Wolbachia bacteria into wild populations of mosquitoes that can interfere with malaria infecting mosquitoes and consideration of genetically engineered mosquitoes.

"All hold promise, but have technological, social and/or regulatory hurdles, and would require considerable money," Paxton said, adding that researchers are also studying Hawaiian honeycreeper genes, to see if they can naturally boost the birds' own immunity. There is also interest in controlling numbers of predatory rats near the birds' breeding areas, and in habitat restoration of Kauai's remote forests to "slow declines and to buy more time."

The new research also serves as a warning for what is predicted to happen on other Hawaiian Islands, such as Maui and the big island of Hawaii. Paxton explained that Kauai's forest habitat is at lower elevations than on these other islands, and so Kauai's forest birds are more vulnerable to the climate change-fueled threats.

"With continued warming, we expect mosquitoes and disease to make their way into those (other Hawaiian Island) forests, with the same devastating consequences for the bird communities of those islands," he said.

PHOTOS OF KAUAI'S ENDANGERED FOREST BIRDS:

Critically endangered 'akikiki birds (Oreomystis bairdi -- a species also known as the Kaua'i creeper), experienced a population decline of 71% from 1981 to 2012, according to a new survey of forest birds native to the Hawaiian island of Kauai.

The 'anianiau (Magumma parva), along with other forest birds native to Kauai, has lost much of its original range over the past few decades. New research has determined that this bird is now limited to a small, remote area of the Alaka'i Plateau wilderness area.

The bright crimson feathers of the 'apapane (Himatione sanguinea) used to adorn the capes, helmets and leis of Hawaiian nobility. The birds have experienced steep population declines in recent years due to disease fueled by climate change, a new study reports.

If the current rate of population decline continues for the Kaua'i 'amakihi (Chlorodrepanis stejnegeri), this forest bird on the Hawaiian island of Kauai could be extinct in just over three decades, new estimates show.