WASHINGTON (CN) – The U.S. Fish and Wildlife Service plans to list 20 species of plants and three species of damselfly on the Hawaiian island of Oahu as endangered under the Endangered Species Act and designate 43,491 acres as critical habitat for those species.
While most of the land to be designated as critical habitat for the species has already been designated as critical for the survival of 99 other plant and animal species, the new designation reinforces the urgency the agency places on the conservation of species it calls the “rarest of the rare.”
The agency believes that four of the plant species, Cyanea purpurellifolia, Cyrtandra gracilis, Cyrtandra waiolani, and Tetraplasandra lydgatei have fewer than 50 known specimens in the wild.
Nineteen of the species proposed for listing are candidate species the agency had previously determined warranted protection under the act but whose listing was precluded by higher priority listing actions.
Among those leaving the candidate list would be three species of damselfly. The blackline Hawaiian damselfly, the crimson Hawaiian damselfly and the oceanic Hawaiian damselfly would join the Pacific Hawaiian damselfly and the flying earwig Hawaiian damselfly on the endangered species list, under the agency’s proposal.
Block listings of species under the act are rare, but the agency has used the approach before, particularly in the Hawaiian Islands where large groups of species that share the same ecosystem face similar threats.
The ecosystem based approach benefits all the species, listed or not, sharing the habitat, because conservation efforts are focused on the overall preservation of the habitat rather than the individual needs of a particular species, according to the agency.
On Oahu, as with other islands in the chain, invasive species and development are the two most common threats to native species.
Oahu is the third largest of the eight main Hawaiian Islands, comprising 600 square miles. Two mountain ranges dominate the island and, along with the prevailing winds, neatly segregate microclimates and animal habitats. Because of the winds, and the orientation of the ranges, there are generally wetter and dryer mountainsides.
This climatic bifurcation tends to isolate species which have evolved specific adaptations to survival in their habitat. Having such specific adaptations means that a species is less likely to survive when habitat is lost to invasives or development.
The agency will accept public comments on the proposed rule until Oct. 3, 2011.