East of the Rockies, Yellow-billed Cuckoo is a common spring and summer resident of open woods and streamsides. West of the Continental Divide, however, the once-widespread species is anything but common.
The cuckoo no longer breeds in British Columbia and probably doesn’t nest in Washington, Oregon, or western Montana — areas where it bred until the 1930s and ’40s. Breeding populations in Idaho, Utah, Nevada, California, and western Colorado, Wyoming, and Texas are tiny. The bulk of the remaining population is in Arizona, western New Mexico, and Mexico.
In October 2013, more than 15 years after conservation groups had proposed the move, the U.S. Fish and Wildlife Service suggested listing the western Yellow-billed Cuckoo as Threatened under the Endangered Species Act.
Federal biologists say more than 90 percent of the bird’s riparian habitat in the West has been lost or degraded. Key factors in the bird’s decline, according to the 46-page listing proposal, include habitat fragmentation, dams and river-flow management, bank protection, overgrazing, and competition from exotic plants — all of which harm the streamside thickets of willows, cottonwoods, and other native trees that cuckoos like.
The agency estimates a total population of 680-1,025 breeding pairs: 350-495 pairs in the United States and 330-530 pairs in Mexico — numbers that the service says may be inflated because some pairs could be counted twice.
Because the population is so low, a Threatened listing is insufficient, says the American Bird Conservancy. It urges the agency to list the cuckoo as Endangered and says reversing its decline would require:
• Removing grazing cattle from riparian areas
• A “much more aggressive” water-management and habitat-restoration strategy
• Changing steady-burning lights on communication towers to flashing lights to reduce bird deaths
• Restricting pesticide use, especially toxic neonicotinoids, in farm fields adjacent to cuckoo nests
• Federal designation of critical habitat — a key to the success of most listings under the Endangered Species Act
Public comments on the proposal were due in late February. The agency says it will make its final listing decision by October.
Read the proposal
Endangered and Threatened Wildlife and Plants; Proposed Threatened Status for the Western Distinct Population Segment of the Yellow-billed Cuckoo (Coccyzus americanus); Proposed Rule, U.S. Fish and Wildlife Service, October 3, 2013. PDF
A version of this article appears in the April 2014 issue of BirdWatching. Subscribe.