Habitat Degradation and Introduced Diseases Stress the Endangered Hawaii Akepa

EPA Grant Number: R829093
Title: Habitat Degradation and Introduced Diseases Stress the Endangered Hawaii Akepa
Investigators: Freed, Leonard A. , Cann, Rebecca L. , Goff, Lee M.
Institution: University of Hawaii at Honolulu
Current Institution: University of Hawaii at Honolulu , Chaminade University of Honolulu
EPA Project Officer: Packard, Benjamin H
Project Period: July 1, 2001 through June 30, 2004 (Extended to October 25, 2006)
Project Amount: $510,375
RFA: Wildlife Risk Assessment (2001) RFA Text |  Recipients Lists
Research Category: Biology/Life Sciences , Ecological Indicators/Assessment/Restoration , Aquatic Ecosystems


The Hawaii akepa (Loxops coccineus coccineus) is an endangered Hawaiian honeycreeper (subfamily Drepanidinae) endemic to the island of Hawaii. The bird nests exclusively in cavities that form only in large trees of old-growth forests, and such trees determine carrying capacity. At Hakalau Forest National Wildlife Refuge, on Mauna Kea, the akepa exists at highest density at upper elevations around 6000 ft, where large trees are at highest density and where the bird is free of mosquito transmitted diseases. The bird declines at 5000 ft and is no longer present at 4000 ft, in association with introduced mosquitoes (Culex quinquefasciatus) and avian malaria (Plasmodium relictum) and pox virus (Poxvirus avium) at mid and lower elevations. In addition, large trees are falling at a faster rate than they are being regenerated between 6000-5000 ft, where the forest has been subjected to clearing for cattle ranching. Multiple stressors are habitat degradation (loss of nest-site trees) and introduced disease, which will be investigated at 6000 ft (upper), 5000 ft (mid), and 4500 ft (low) elevations. Objectives are: 1) document habitat structure and estimate density of the bird at the mid and low elevation sites, to determine if the bird density is at or below carrying capacity; 2) estimate prevalence of disease and mosquitoes in all three sites, to determine if higher prevalence is associated with densities below carrying capacity; 3) compare demography of the akepa in all three sites, to determine if lower juvenile and adult survival in the lower elevation sites is associated with infection; and 4) compare genetic population structure of the bird along the elevational gradient, to determine if genotypes that may have evolved tolerance or resistance to malaria are restricted to low elevations.


A sensitive genetic test will be used that can estimate intensity as well as presence of infection in a mosquito or in the blood sample from a bird. Mark/recapture techniques, involving mist-netting and banding birds, will be used in conjunction with a computer program that can compare demographic parameters of healthy and infected individuals. Mitochondrial and microsatellite DNA will be used for documenting genetic population structure of the bird along the elevational gradient. Habitat quality will be assessed in the different study areas by estimating the density of large trees with cavities, and the loss of such trees.

Expected Results:

The research is designed to determine the extent to which the elvational decline of the bird is based on habitat quality or introduced diseases, and to evaluate how population genetics and demography impact models of risk management.

Publications and Presentations:

Publications have been submitted on this project: View all 2 publications for this project

Journal Articles:

Journal Articles have been submitted on this project: View all 1 journal articles for this project

Supplemental Keywords:

conservation, epidemiology, ecology, entomology, ornithology, risk assessment, demography, population genetics, molecular diagnostics., RFA, Scientific Discipline, Geographic Area, Ecosystem Protection/Environmental Exposure & Risk, wildlife, Ecosystem/Assessment/Indicators, State, Ecological Effects - Environmental Exposure & Risk, Environmental Monitoring, Ecological Risk Assessment, Ecology and Ecosystems, ecosystem modeling, environmental health, habitat, molecular epidemiology, risk assessment, assessment models, ecology, ecosystem assessment, endangered species, molecular diagnostics, demographic data, population gentics, animal responses, bird habitat, environmental risks, conservation, Wildlife Risk Assessment, Hawaii, habitat loss, genetic testing, ecological assessment, ecological impacts, ecosystem indicators, risk models, birds, ecosystem health, environmental stress, gentic testing, ecological models, ecosystem stress, ornithology, HI, disease, ecological research

Progress and Final Reports:

  • 2002 Progress Report
  • 2003
  • 2004
  • 2005
  • 2006
  • Final