The yellow-billed cuckoo is a rather striking bird. It has grayish brown plumage above and white below, red primary flight feathers, and tail feathers that have a bold pattern that almost looks like a white and black braid.

The yellow-billed cuckoo is a member of the avian family Cuculidae. Some ornithologists have separated the species into eastern and western subspecies, which is a controversial distinction. However, for conservation purposes, the two populations are listed as distinct population segments.

The western yellow-billed cuckoo, Coccyzus americanus, is a medium-sized bird about 12 inches in length that weighs about two ounces. It is listed as a “threatened” species under the federal Endangered Species Act and as an “endangered” species under the California Endangered Species Act.

The breeding range of the yellow-billed cuckoo once included most of North America from southern Canada to the Caribbean and northern Mexico. In recent years, the species’ distribution in the west has greatly contracted. The northern limit of breeding in the western coastal states is now in the Sacramento Valley.

Yellow-billed cuckoos typically live in woodlands in large riparian (wetland) habitats such as cottonwood-willow forests. The birds require contiguous patches of multilayered riparian habitat for nesting. It is thought that the multiple layers, which provide more shade and moisture, create cooler and more humid streamside conditions which are important for nesting success. They are also found in desert riparian areas, such as those in and around the Big Maria Mountains and Riverside Mountains (north of Blythe) and the Vidal area which is located north of Parker.

Western yellow-billed cuckoo numbers have decreased dramatically over the past several decades. Eastern yellow-billed cuckoo numbers have also declined but not nearly as drastically.

Western yellow-billed cuckoos are no longer found in British Columbia or the Pacific Northwest. Most of the remaining birds are found in isolated patches of riparian habitat along rivers in Arizona, California, and New Mexico. Surveys in California during 1986-1987 found only 30-33 pairs remaining in the state, compared with an estimated 15,000 pairs in the late 1800s.

As a result of these declines, in 2014 the U.S. Fish and Wildlife Service listed the western distinct population segment of the yellow-billed cuckoo as “threatened.” The state of California took action much more quickly, listing the birds as “endangered” in 1988.

Much of the dramatic decline of the yellow-billed cuckoo in California has been directly attributed to breeding habitat loss and degradation from lands being converted to agricultural and other urban uses, dams and river flow management, stream channelization and stabilization, and livestock grazing. In addition, groundwater pumping and the replacement of native riparian habitats by invasive non-native plants, particularly tamarisk, have substantially reduced available habitats.

Pesticide use is also likely harming western yellow-billed cuckoos. Reproduction problems caused by eggshell thinning have been documented in western yellow-billed cuckoos. They may also be ingesting pesticides by eating caterpillars, frogs, or other prey using polluted runoff from agricultural fields, may also be sources of contamination.

Climate change also has the potential to cause more of a decline in the numbers of western yellow-billed cuckoos. Warmer temperatures may alter the composition of riparian forests over time, as well as alter the timing of peak insect arrival in relation to when cuckoos arrive in their breeding grounds to feed on this critical food source.

The good news is that restoration projects are already in place to protect and restore riparian habitat in the southwestern United States that could benefit the western yellow-billed cuckoo. For example, the Lower Colorado River Multi-Species Conservation Program calls for restoring more than 4,000 acres of habitat for the bird.

There are things you can do to help the yellow-billed cuckoo. When landscaping your yard, plant native trees like cottonwoods and willows, which support the cuckoo’s insect prey. Avoid using pesticides on your landscaping; many brands kill the caterpillars on which the cuckoo depends. Keep your cats inside. Cats, even those that are well-fed, kill millions of birds per year. In addition, whenever you go to natural areas, in particular riparian areas, observe all signs telling you how to protect wildlife and plants.

Linda Castro is a nature enthusiast and animal lover. She is the Assistant Policy Director for the California Wilderness Coalition and serves on the board of the SCV-based Community Hiking Club.  Her commentaries relate to California’s deserts.