Rare Cuckoo Needs Greater Protection, Group Urges

The U.S. Fish and Wildlife Service wants to protect a vanishing California songbird by listing it as Threatened under the Endangered Species Act, but a national bird protection group says that doesn't go far enough.

The Washington D.C.-based American Bird Conservancy (ABC) says that USFWS should give the western yellow-billed cuckoo full Endangered status, which would give the bird greater protection.

A subspecies of the far more widespread yellow-billed cuckoo, the western yellow-billed cuckoo (Coccyzus americanus occidentalis), has seen between 90 and 99 percent of its preferred riparian forest habitat destroyed in California. Fewer than 500 breeding pairs of the birds remain in the United States.

USFWS proposed the western yellow-billed for listing as Threatened in October, as part of a 2011 agreement with the Center for Biological Diversity to rule on listing proposals for 757 imperiled species. ABC made its recommendation for greater protection in a December 2 letter that the group made public December 6.

Yellow-billed cuckoos make their living by eating insects, usually by gleaning them from tree branches. Caterpillars are a special favorite food. Unlike the European cuckoos famous for what ornithologists call "nest parasitism" -- laying their eggs in other birds' nests and leaving the task of rearing the hatchlings to the "host" birds -- yellow-billed cuckoos usually tend their own eggs in their own nests. When there's a bumper crop of edible insects, though, yellow-billeds will resort to nest parasitism to boost the chances that more young will be able to take advantage of the bounty, with "volunteer" hosts taking on the work of feeding.

The western subspecies' range historically extended from southwestern British Columbia and central Colorado to California and Texas and southward into the Mexican states of Baja California, Sinaloa, and Chihuahua. The birds has been extirpated from almost all the northern section of its range. None have been seen in B.C., Washington, Oregon, or Montana for some years, and the populations in Idaho and Texas are down to no more than 20 pairs in each state. Nevada, Colorado, Utah, and Wyoming's numbers are smaller than that. In Arizona, the U.S. stronghold of the subspecies, the cuckoo's population has fallen by 70 to 80 percent since the 1980s.

A 1987 study found the western yellow-billed cuckoo's breeding habitat in California was down to a handful of sites in cottonwood and willow forests along the Sacramento, Amargosa, Kern, Santa Ana, and Colorado rivers. (The Kern River population has been studied especially closely.)

Threats to the bird include depletion of its riverbank woodland habitat, as well as collisions with communications towers during its migration between western North America and the Amazon. The same neonicotinoid pesticides increasingly implicated in bee colony collapse pose a threat to the cuckoo: the birds feed on insects the pesticides are used to eradicate, and such pesticide use both reduces the bird's available food base and poses the risk of secondary poisoning.

While ESA protects species that are listed either as Endangered (generally defined as species at immediate risk of extinction) or Threatened (species thought likely to run the risk of becoming extinct in the near future), the protections for Endangered species are stricter. Among other differences, federal agencies have more leeway in crafting special regulations to water down protections for Threatened species if their protection would conflict with human use of the species habitat.

Endangered status precludes such "special regulations," allowing conservation measures to restore the species that are much more comprehensive, subject to fewer economically driven exceptions.

According to ABC, that agency leeway poses a risk to the western yellowbilled cuckoo. Much of the bird's remaining habitat is on public land managed by either the Bureau of Land Management or the U.S. Forest Service, and ABC suggests that those agencies' "discretion" in protecting the bird has resulted in an across-the-board crash in population on those lands.

"Federal agencies must address water diversion and grazing policies that are disastrous to the cuckoo," said ABC's Steve Holmer in a press release issued Friday. "They need to reverse direction, stop the degradation, and develop a plan to restore riparian areas and regrow lost Yellow-billed Cuckoo habitat."

In addition to bumping the cuckoo's listing status up a notch to Endangered, ABC is calling for stricter controls on grazing and pesticide bans in the bird's critical habitat.