Congress has just beaten back a bid by far right Republicans to effectively kill the endangered species list by making it impossible to add new species, presumably believing that all endangerment is a thing of the past. Even many Republicans rebelled at this exercise in extremism. Still, just because the list exists doesn't mean all critters, even rare ones, will make it on. A case in point: The July 26 decision by the U.S. Fish and Wildlife Service not to list the elusive Driloleirus americanus, otherwise known as the Giant Palouse Earthworm (GPE), as a threatened or endangered species. (See petition to list here, and decision here.)
Part of the reason is that it's turning out that "Palouse" is a misnomer. Environmental activists have wanted the worm listed because it has become extremely rare in the habitat where it was discovered in the late 19th century, the marvelously rich-soiled rolling dunes of the Palouse in southeastern Washington and nearby Idaho. And it is believed rare because more than 99 percent of the original prairie has been deeply disturbed by agriculture and development. There are only a few, tiny remaining pockets of original prairie habitat left, and it seems the giant worms did not take well to the plow.
For decades, no live specimens of the large (reports of up to three-feet), white (not albino), lilly-scented (in dispute) earthworms were found, and recent finds have been major events, at least among scientists, worm experts, and Palouse preservationists. The great white worms are so rare that little is known about them: Where and how they live, breed, what they eat, what kinds of soils they require, etc. The dilemma is that unless more is known, it cannot be known whether or not they are endangered.
But it is also turning out that the GPE is not so limited in its habitat. While they might have once been common in the Palouse, it turns out their range is much greater. They have been found in the forested hills of Idaho, near Leavenworth, west of Ellensburg in the Cascades, and possibly even farther afield (the coast range of Oregon). They've been found in grasslands, Doug fir forests, and Ponderosa pine country. This complicates the "endangered" element considerably, because science has yet to get a fix on the species' true range and numbers. It could be that they are thriving in some places even as they have dwindled elsewhere, or it could be they are simply very hard to find in general.
The report turning down the GPE for listing is a fascinating document because it pulls together the state of knowledge about the worm, and emphasizes our lack of knowledge.
The GPE is thought to be a native species. Little is known about what worms lived in our soils before the ice age, and it is thought that most were wiped out by the scoring and scouring of the Pleistocene glaciation, which covered much of the northern tier of what is now Washington. Most earthworms found here today are non-native. So GPE's are most likely to be found in places that were not covered by ice, which includes pockets that avoided glaciation (such as some higher altitude spots, it turns out) and, later, ground-disturbing development. Still, some specimens have been found in second-growth forest, meaning that not all surface disturbances spell doom for the worms. And there are other impacts that deserve more study. What has been the impact on the GPE of non-native worm species invasions or of pesticides?
Given that so little is yet understood about the worm, it would seem a wise course to at least act as if the species is threatened. The Fish & Wildlife Service says that in its Palouse habitat there are virtually no worms found in agricultural areas, meaning that the damage has probably already been done there. They appear to survive only in small numbers in non-tillable remnants.
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