The plight of Hawaiian birds

The island of Kaua’i

Just last week, two Hawaiian bird species from the island of Kaua’i and their respective habitats were put on the endangered species list along with a Hawaiian fly and 45 types of Hawaiian plants. However, while the action signifies movement from the Obama Administration toward protecting at-risk species and their habitats, the listing does not come a second too soon: Recent research shows U.S. birds, especially in Hawaii, are in great peril.

The U.S. Fish and Wildlife Service (FWS) has listed two types of honeycreepers in the finch family—the ‘akeke‘e, or Kaua‘i ‘akepa, and the ‘akikiki, or Kaua‘i creeper—with the other 33 endangered (and one threatened) Hawaiian birds. From the 1800s to 2007, the ‘akeke‘e population has dropped to approximately 3,500 birds, and the ‘akikiki population has declined by about 80 percent in the last 40 years to approximately 1,300 birds.

In addition to listing the birds, the FWS designated a total of 26,582 acres in six different ecosystem types as critical habitat. FWS plans to use an ecosystem approach to protect species over the next several years. Secretary of the Interior Ken Salazar described the habitat preservation in an FWS press release:

The ecosystem-based approach that our scientists used to make this decision represents an efficient and innovative model for conserving imperiled species and their habitats. By highlighting species that share ecosystems and common threats, we can more effectively focus conservation management efforts to address these threats and restore ecosystem function for these species and the entire ecological community.

Ecosystem preservation and recovery efforts are critical: Hawaiian birds are threatened by invasive species, such as feral pigs and cats, and Asian tiger mosquitoes. Mosquitoes, which are nonnative to the Hawaiian Islands, serve as vectors for avian pathogens. So feral pigs are a particular danger because they dig holes in the forest floor when looking for food, creating basins for water to gather and for disease-carrying mosquitoes to breed.

The endangered ‘akikiki Credit: Jack Jeffrey, USGS

And according to The State of the Birds, a 2010 report released last week on the effects of climate change on bird conservation, global warming on Kaua’i has the potential to cause an 85% decrease in habitats that are naturally low-risk areas for avian malaria and pox. That is, the cooler temperatures in elevated terrain on the Hawaiian Islands protect birds from mosquito-borne illnesses: The malaria parasite cannot completely develop in birds living at 55°F and below. As the temperature rises, however, the birds become more susceptible to illness. The report concludes that, in all, an estimated 93% of Hawaiian birds exhibit medium or high vulnerability to climate change.

Another study, published in the March issue of Biological Conservation, discovered another grim outcome for Hawaiian birds. Chris Elphick from the University of Connecticut and colleagues examined current methods of determining a species’ extinction date. After fine-tuning the framework to include International Union for Conservation of Nature risk categories, years of last confirmed sightings and number of years with confirmed records, they reevaluated 52 rare North American and Hawaiian bird species that could have gone extinct during the last 200 years.

They found that of the 52 species—a vast majority of which were Hawaiian—all were very likely extinct. As Elphick and colleagues describe, there are a few exceptions that would make continued efforts worthwhile, like the ‘alalā species:

Even in the case [of the ‘alalā], however, the possibility of persistence is not high, and if confirmed sightings are not forthcoming by 2014 it would be reasonable to conclude with a high level of confidence that the population is extinct. Of the remaining populations, those for which there is the greatest (albeit small) chance of persistence, and thus for which search efforts would be least unlikely to fail, are the oloma’o population on Moloka’i, Maui ‘ākepa, po’o-uli, ‘ō‘ū on Kaua’i, and the Kaua’I ‘ō‘ō.

The researchers recommend using sighting record methods as they did to prioritize conservation efforts. In this time of limited funds and heightened risk, this method could help determine the allocation of resources for the future conservation of Hawaiian birds. And they need all the help they can get. / CC BY-NC-ND 2.0

Elphick, C., Roberts, D., & Michael Reed, J. (2010). Estimated dates of recent extinctions for North American and Hawaiian birds Biological Conservation, 143 (3), 617-624 DOI: 10.1016/j.biocon.2009.11.026