UH Hilo publishes online report on emerging disease in native birds

The report is on an emerging infectious disease, knemidokoptic mange, commonly called “scaly leg,” that threatens population recovery of a Hawaiian honeycreeper. The study is now available to the public.

A beautiful little green bird with black, slender bill, is held gently by the legs. One leg is banded.
A healthy Hawai‘i ‘amakihi. Photo by Noah Khan, U.S. Fish and Wildlife.
A person hold a little green bird with deformed feet.
Result of knemidokoptic mange on the legs and feet of a Hawai‘i ‘amakihi.

The University of Hawai‘i at Hilo, in collaboration with the Pacific Island Ecosystems Research Center of the U.S. Geological Survey, announces the online availability of the report, “Distribution and prevalence of knemidokoptic mange in Hawai‘i ‘Amakihi on the island of Hawai‘i.” The Hawai‘i ‘amakihi (Hemignathus virens) is a species of Hawaiian honeycreeper that evolved in the forests of Hawai‘i and is found nowhere else in the world.

The report, now available to the public, summarizes the current status of an emerging infectious disease, knemidokoptic mange, in native birds on the island of Hawai‘i. The disease is caused by the skin-burrowing mite, Knemidokoptes jamaicensis, and may result in severe deformities of the feet and drops in population levels.

“Although Hawai‘i ‘amakihi are becoming more common in lowland forests, emerging infections like knemidokoptic mange may slow, or even halt, population recovery,” says Dennis LaPointe, a research ecologist with the USGS Pacific Island Ecosystems Research Center and an author of the report.

Jacqueline Gaudioso in a cap.
Jacqueline Gaudioso, a graduate of UH Hilo, first discovered knemidokoptic mange in native birds while doing research for her master of science degree.

Knemidokoptic mange, sometimes called “scaly leg,” was first detected in the native bird Hawai‘i ‘amakihi in 2007 by the lead author of the report, Jacqueline Gaudioso, then a graduate student in UH Hilo’s tropical conservation biology and environmental science program and now a USGS employee.

The results of an island-wide survey of key native forest bird habitats revealed an infestation limited to Hawai‘i ‘amakihi but spreading from low elevation, leeward Mauna Loa, to higher, leeward elevations, and west to low elevation forests in Puna.

Analysis of preliminary findings indicates some correlations between avian malaria, wetter habitat, and knemidokoptic mange, and provides some evidence of an impact on individual survival. The report adds to the understanding of this emerging infectious disease in wild bird populations and offers some insights into management of disease at the local level.

The report is published by UH Hilo’s Hawaiʻi Cooperative Studies Unit as part of its technical reports series. The document and research are the result of a collaborative partnership between researchers from USGS and UH Hilo.

The research was supported through funding from the U.S. Fish and Wildlife Service (Pacific Islands Fish and Wildlife Office), Hawai‘i Division of Forestry and Wildlife, and the U.S Geological Survey Ecosystems Program.

Hawai‘i Cooperative Studies Unit Technical Report HCSU-055, “Distribution and prevalence of knemidokoptic mange in Hawai‘i ‘amakihi on the island of Hawaii,” by J.M Gaudioso, D.A. LaPointe, C.T. Atkinson and C. Apelgren, published by UH Hilo.

-Adapted from a press release by the authors of the study