Mark Snyder, (509) 893-8019 or Tom Buckley, (509) 893-8029
The U.S. Fish and Wildlife Service has reviewed a petition to protect the giant Palouse earthworm (Driloleirus americanus) as a threatened or endangered species under the Endangered Species Act and concluded the petition does not contain substantial scientific data indicating that the petitioned action might be warranted.
The Service made the determination in response to a petition received on August 30, 2006, from the Palouse Prairie Foundation, the Palouse Audubon Society, Friends of the Clearwater, and three private citizens seeking to add the giant Palouse earthworm to the Federal list of Endangered and Threatened Wildlife and Plants. The Service reviews all petitions to decide whether they contain substantial scientific information indicating that listing may be warranted.
"We share the petitioners concern for the species," said Susan Martin, supervisor for the Upper Columbia Fish and Wildlife Office in Spokane, Washington. "While we will not be initiating an in-depth status review at this time, we will continue to cooperate with others to monitor the species status, trends, and life history needs, and we encourage interested parties to continue to provide us with information that will assist with the conservation of the species."
The giant Palouse earthworm was first described in 1897 after its discovery near Pullman, Washington. This species was thought to be very abundant in that region. Although only a few specimens have been collected, early descriptions and collection locations indicate that the giant Palouse earthworm utilizes grassland sites with good soil and native vegetation of the Palouse bioregion. The Palouse bioregion includes parts of southeast Washington, west central Idaho, and a small portion of northeast Oregon.
There is very little known about the giant Palouse earthworm in the scientific record. Information regarding the range, distribution, population size, and status of the giant earthworm is very limited, preventing the assessment of population trends. This limits the Services ability to assess whether the species may be impacted by the threats listed in the petition.
After careful consideration of the petition and the information it provided, the Service found that while the Palouse prairie has experienced a dramatic conversion of native habitat to agricultural practices, information linking the effect agricultural practices that utilize chemicals and result in soil compaction and composition has had on the earthworm is currently nonexistent. In addition, the Service found no information on predation or transmission of pathogens by exotic earthworms to the giant Palouse earthworm. Though there are no existing regulatory mechanisms for the giant Palouse earthworm or for other native earthworms, so little information exists about the population size, trends, habitat needs and limiting factors of the giant Palouse earthworm, the Service could not determine if a lack of regulations may pose a threat to the species.
The giant Palouse earthworm may grow up to 3 feet or more in length and a half inch in diameter, is white to light pink in color, and is said to emit a lily-like fragrance when handled. Giant Palouse earthworms inhabit permanent or semi-permanent vertical burrows and emerge at night to feed on relatively fresh plant debris at the surface.
The species is reported to make burrows more than 15 feet deep, in which it can move rapidly to escape capture. This may account for the fact that, in the presence of studies of native earthworms in the bioregion, there have been only a few recorded sightings of the giant Palouse earthworm since it was discovered in 1897.