Nene recovering! But climate change threatening future of Hawaii's forest birds

A bleak future? Deadly bird diseases creeping up Hawaiian mountains with climate change: For decades, world health experts have been predicting an increase in the occurrence and geographical spread of mosquito-borne human disease due to global warming trends. Similarly, climate change in the Hawaiian Islands could have a profound effect on the altitudinal distribution and severity of non-native mosquito-borne avian disease. The most diverse communities and abundant populations of native forest birds are restricted to forests above 1700 meters in elevation where transmission of avian disease is limited by the effect of low environmental temperatures on development of avian malaria and the seasonality and abundance of the mosquito.

On the islands of Kauai and Hawaii there is evidence that transmission of avian malaria may be increasing in these high elevation forests. Current land-use practices, climate change and the distribution of forest habitat cannot provide a future refuge from avian malaria and suggest a bleak future for some endemic Hawaiian forest birds. Introduced mosquito-borne avian disease likely played a key role in the extinction of many Hawaiian forest bird species and remains a main factor limiting the range and abundance of highly endangered endemic forest species today.

This study, Between a rock and a warm place: climate change and the fate of endemic Hawaiian forest birds, will be presented on Nov. 6 at 9:20 a.m. in Room Kohala 1. Contact Dennis A. LaPointe, 808-985-6413 (office) or 808-640-9165 (cell), dennis_lapointe@usgs.gov.

Specialization limits options for Hawaiian forest birds: The decline of Hawaii's native forest birds is linked to their bill shape and size, which limits the kinds of food they can secure for themselves and their young. During the past 150 years, the species that have most often declined in numbers and range are those with bills that are unusually long, curved, stout or symmetrical. They also produce fewer offspring than do birds that have relatively ordinary bills. Consequently, specialists are more vulnerable to threats from invasive species and other environmental changes.

This study, The evolution of feeding specialization in Hawaiian forest birds and its ecological consequences, will be presented on Nov. 7 at 8:20 a.m. in Room Kohala 1. Contact Paul Banko, 808-985-6402, paul_banko@usgs.gov.

Caterpillars are important food for native forest birds but under threat from alien wasps: Diet studies of native Hawaiian forest birds from the Big Island and Maui show that caterpillars are the most common prey item consumed. These larval insects are particularly important for the endangered akepa, akiapolaau, Hawaii creeper and kiwikiu (Maui parrotbill). The widespread and abundant non-native Japanese white-eye also consumed caterpillars, but preferred homopteran insects and spiders to a greater extent, suggesting overlap in diet with the endangered birds is not extensive. Perhaps a greater threat to the caterpillar food supply is alien parasitoid wasps that kill caterpillars; unfortunately, these insects appear to have infiltrated nearly all forest habitats in Hawaii.

This study, Diets of endangered Hawaiian forest birds and threats to their arthropod prey base, will be presented on Nov. 7 at 8:40 a.m. in Room Kohala 1. Contact Bob Peck, 808-967-7396, bwpeck@usgs.gov.

The Hawaiian goose finds its way back home: The endangered Hawaiian goose, traditionally known as the Nēnē, nearly went extinct in the middle of the twentieth century but has been making a slow comeback thanks to the hard work of several management agencies. In the late 1990s, nenes started showing up at places they had not been seen in 60 years – without any help from people. USGS researchers have been using satellite telemetry and confirming that nene are now making the same seasonal movements that early naturalists described more than a century ago; breeding in the low-elevation grasslands and flying to high-elevation shrublands at other times of year. Although nene are among the most terrestrial of all geese, they stay close to water while they are molting and flightless, presumably to make a quick escape from predators.

This study, Tracking movements of the endangered Hawaiian goose with satellite telemetry, will be presented on Nov. 7 at 10:10 a.m. in Room Kohala 1. Contact Steve Hess, 808-985-6401, shess@usgs.gov.

Hawaiian forest birds adapt on their own to introduced diseases: Hawaii amakihi, an endemic honeycreeper from the Hawaiian islands, is expanding in numbers in some low elevation habitats on the Big Island of Hawaii, in spite of high rates of transmission of introduced avian malaria. This disease, in concert with the introduced mosquito vector, has had devastating impacts on native honeycreepers, restricting most to cool, high-elevation refugia where temperatures limit mosquito numbers and disease transmission. Experimental data gathered by USGS researchers and collaborators points to evolved tolerance to malaria as a possible mechanism for this recent low-elevation population expansion and adds a new twist to long-term conservation efforts for Hawaii's remaining threatened and endangered species.

This study, Tolerance to avian malaria in Hawaiian forest birds: a new paradigm for managing disease?, will be presented on Nov. 7 in Room Kohala 1 at 11:10 a.m. Contact Carter Atkinson, 808-985-6401, catkinson@usgs.gov.

Provided by United States Geological Survey