The yellow-billed cuckoo is a medium-sized bird found throughout much of North America. In recent decades, the yellow-billed cuckoo population has declined significantly, leading many to wonder if the species is endangered. This article will examine the current status of the yellow-billed cuckoo, the reasons for its population decline, and whether it warrants listing under the Endangered Species Act.
What is the yellow-billed cuckoo?
The yellow-billed cuckoo (Coccyzus americanus) is a member of the cuckoo family Cuculidae. It is a medium-sized bird measuring about 12 inches (30 cm) in length and weighing around 2 ounces (60 grams).
The yellow-billed cuckoo has a slender body with long tail feathers. As its name suggests, it has a yellow lower mandible. Its upper parts are brownish gray with rufous primary flight feathers. The underparts are white.
This cuckoo species is found during the breeding season across much of the contiguous United States and southern Canada. Its wintering range extends from southern Mexico through Central America.
The yellow-billed cuckoo inhabits open woodlands with dense vegetative cover. It often nests in willow, alder and mesquite trees. Its diet consists mainly of insects, including caterpillars, katydids, cicadas, grasshoppers and beetles. It may also eat some fruits and berries.
What is the yellow-billed cuckoo’s current population status?
The yellow-billed cuckoo has experienced significant population declines since the 1960s. The exact current population is unknown, but estimates range from 350,000 to 495,000 individuals.
Breeding Bird Survey (BBS) data shows an average decline of 2.7% per year between 1966-2015. Christmas Bird Count data indicates the population declined by as much as 75% between 1970 and 2014.
Due to these declines, several organizations have listed the yellow-billed cuckoo as a species of conservation concern:
- The International Union for Conservation of Nature (IUCN) classifies the yellow-billed cuckoo as “Near Threatened.”
- It is listed as a “Sensitive Species” by the U.S. Forest Service.
- The species has “High Concern” status in Canada.
- Many state agencies classify it as endangered, threatened or of special concern.
While substantial declines have occurred across many parts of the yellow-billed cuckoo’s range, some local populations remain stable. Overall though, the species warrants close monitoring.
Why is the yellow-billed cuckoo declining?
There are several factors that contribute to the yellow-billed cuckoo’s dwindling numbers:
Habitat loss
Loss of riparian habitat is a major threat. The yellow-billed cuckoo nests in forested wetlands along rivers and streams. Clearing of trees for agriculture and development has destroyed much of this habitat. For example, an estimated 95% of its nesting habitat in California has been lost.
Pesticide use
The yellow-billed cuckoo is vulnerable to pesticide use, especially neonicotinoids. These insecticides reduce its food supply of caterpillars, cicadas and other insects. Studies have found neonicotinoid exposure impacts cuckoo reproduction and fledgling success.
Climate change
Climate change may exacerbate droughts and alter precipitation patterns, further degrading the streamside habitats used by the cuckoo. Hotter temperatures also raise the bird’s risk of overheating.
Lack of habitat management
Proactive habitat management is needed in many areas to maintain the dense understories favored by yellow-billed cuckoos. Lack of sufficient habitat management allows overgrowth of vegetation.
Range shifting
The yellow-billed cuckoo’s range has shifted northward as the climate warms. This has led to declines in the southern portion of its range. Range shifts may indicate climate-related stress.
Is the yellow-billed cuckoo legally endangered?
The yellow-billed cuckoo is not currently listed under the Endangered Species Act (ESA). However, there have been efforts to get it listed:
- It was proposed for ESA listing in 2001 but withdrawn in 2006 due to lack of resources.
- The species was petitioned for listing again in 2013 and received a positive 90-day finding.
- In 2020, the US Fish and Wildlife Service found ESA listing was “warranted but precluded” by other priorities.
So while not legally protected as endangered yet, the yellow-billed cuckoo may join the ESA list in the future if population declines continue. Several individual states currently classify it as endangered/threatened at the state level.
How can we help the yellow-billed cuckoo?
Since habitat loss is a major issue facing the yellow-billed cuckoo, protecting and restoring riparian forests will benefit the species. Other conservation actions that can help include:
- Managing vegetation to maintain dense understory foliage.
- Allowing natural flooding regimes that regenerate habitat.
- Controlling pesticide use in areas where cuckoos are known to breed.
- Protecting large tracts of habitat to support breeding pairs.
- Monitoring populations to identify trends.
Community science efforts such as bird counts and nest monitoring provide valuable information to guide management strategies. The public can participate in many of these programs.
Conclusion
In summary, the yellow-billed cuckoo has experienced concerning population declines due to threats such as habitat loss, pesticides, climate change, and inadequate habitat management. While not currently federally listed as endangered, many experts believe the yellow-billed cuckoo warrants increased conservation action. Protecting riparian ecosystems and managing habitat specifically for this species will be important steps. Continued monitoring and research are also needed to fully understand the environmental factors impacting its populations. With appropriate conservation efforts, hopefully the unique yellow-billed cuckoo can be recovered across its range.