The U.S. Fish and Wildlife Service announced Monday that it's seeking public comments on whether or not one of California's rarest and most photogenic predators should be listed as Threatened or Endangered under the U.S. Endangered Species Act.
The Humboldt marten, Martes caurina humboldtensis, is so rare that it was actually considered extinct until a few surviving individuals were discovered in 1996. Once occurring throughout the redwood belt of the California coast from Sonoma County north into Oregon, the marten has been extirpated from at least 95 percent of its range in California, and now survives only in Del Norte County and in two small populations in Oregon.
There are thought to be no more than 200 of the cat-sized, tree-climbing carnivores left in the world. A subspecies of the more wide-ranging Pacific marten, the Humboldt marten has been devastated by destruction of the old-growth forest habitat on which it depends, and its remaining numbers are likely threatened by unregulated use of rodent poisons on the northwest coast's numerous illegal cannabis farms.
The Humboldt marten is a reddish weasel about the size of a housecat that lives in ancient forest and serpentine shrublands, where it eats small mammals and birds, lizards, insects, and berries. The marten was the subject of a 2010 petition by the Center for Biological Diversity (CBD) and the Arcata-based Environmental Protection Information Center (EPIC), asking the USFWS to list the subspecies as either Endangered or Threatened. In 2012, the agency issued a 90-day finding saying that listing the marten might well be justified.
Monday's announcement is essentially an update on USFWS's progress in untangling a scientific question about the relationship between the California martens and two populations in Oregon. At the time CBD and EPIC petitioned USFWS to list the Humboldt marten, the populations in Oregon were generally considered part of a different subspecies, which occupies the Cascade Range from Oregon through British Columbia.
Complicating things somewhat for the lay reader is the fact that when the petition was first filed, conventional wisdom had it that there was just one species of marten in North America, Martes americana. In 2012, that species was split in two, with populations west of the Rocky Mountains assigned the species Martes caurina.
That reassignment to a western species doesn't affect the relationships between the California population of Humboldt martens and the two western Oregon populations, but recent genetic research into the animals does. It's now thought likely that those two Oregon populations are more closely related to the Humboldt marten than they are to martens elsewhere in Oregon, now called Martes caurina caurina.
And if those Oregon populations turn out to be closely related enough to the Humboldt marten to deserve inclusion in the same subspecies or "distinct population segment," that will affect USFWS' decision. The agency could decide that greater numbers in the subspecies mean a lower rank on the ESA list, though the rarity of animals in all three populations would argue against that on a strictly scientific basis. At the very least, the determination will affect USFWS' designation of critical habitat for the marten.
The USFWS says it expects to untangle this taxonomic puzzle and publish its finding on listing the Humboldt marten by April 1, 2015.