Cuckoo birds are a group of birds belonging to the Cuculidae family. They are best known for their unique breeding behavior where female cuckoos lay their eggs in the nests of other bird species, leaving those birds to raise their young. This behavior is called brood parasitism. There are about 140 species of cuckoo birds worldwide, but only a few species regularly occur in North America. In this article, we’ll look specifically at whether cuckoo birds can be found in the state of Idaho.
Cuckoo Species in North America
There are only two cuckoo species that regularly breed in North America north of Mexico:
- Yellow-billed Cuckoo (Coccyzus americanus)
- Black-billed Cuckoo (Coccyzus erythropthalmus)
Both species breed during the summer months across much of the eastern and central United States and southern Canada. Their breeding range extends westwards as far as eastern Colorado, eastern Montana, and western Texas.
A third species, the Mangrove Cuckoo (Coccyzus minor), is a very rare summer visitor along the southeastern US coast.
Range of the Yellow-billed Cuckoo in Idaho
Of the two common species, only the Yellow-billed Cuckoo is known to occur in Idaho. However, it is not found throughout the entire state.
The Yellow-billed Cuckoo breeds in scattered locations in the southwestern and south-central regions of Idaho. Its breeding range centers around the Snake River and its tributaries, including the Boise, Payette, and Weiser rivers.
Breeding populations likely exist along these river corridors in Owyhee, Canyon, Gem, Payette, Washington, Ada, Elmore, and Gooding counties.
Outside of the Snake River drainage, breeding may occur locally along rivers and streams in the Bear River drainage in southeastern Idaho.
Habitat Preferences
The Yellow-billed Cuckoo inhabits riparian woodlands dominated by cottonwoods and willows in Idaho. This includes forests and shrublands growing along rivers, streams, oxbow lakes, and other wetlands.
Cuckoos often nest in large tracts of contiguous habitat with a dense shrub layer and open understory. They usually avoid drier upland habitats away from watercourses. Habitat patches as small as 10 acres may attract breeding cuckoos if the vegetation structure is suitable.
Arrival and Departure from Idaho
The Yellow-billed Cuckoo is a summer visitor to Idaho that does not overwinter in the state. The birds arrive back on their Idaho breeding grounds in mid to late May. They quickly get to work building nests, laying eggs, and raising young.
By late August and early September, adults and young-of-the-year cuckoos depart on their migration back to South America. The species winters primarily in northern South America east of the Andes Mountains.
While in Idaho, cuckoos are exclusively insectivores feeding on large insects like grasshoppers, cicadas, caterpillars, and katydids. Before migration, they switch to eating mostly fruit to accumulate fat reserves.
Population Trends in Idaho
Across its western breeding range, the Yellow-billed Cuckoo has experienced sharp population declines since the early 1900s. Habitat loss is considered the biggest threat.
In Idaho, the conversion of native riparian forests to agricultural land has substantially reduced cuckoo breeding habitat, especially at lower elevations. River flow regulation by dams has also altered conditions.
Due to declining numbers, the Yellow-billed Cuckoo is listed as a state endangered species in Idaho. Breeding populations here are small and fragmented.
In 2000, Idaho’s first statewide cuckoo survey located an estimated statewide population of just 35 individual birds. The species faces an uncertain future in the state if habitat loss continues.
Cuckoo Conservation Efforts
Several conservation initiatives aim to protect and restore Yellow-billed Cuckoo habitat in Idaho:
- The Idaho Department of Fish and Game has designated the Yellow-billed Cuckoo as a “Species of Greatest Conservation Need” in its Idaho State Wildlife Action Plan. This plan identifies key conservation actions needed such as habitat protection, restoration, and population monitoring.
- The Bureau of Land Management has proposed designating about 75 miles of streamside habitat along the Snake and Bruneau rivers as Areas of Critical Environmental Concern to protect cuckoo habitat.
- The U.S. Fish & Wildlife Service has proposed listing the western Distinct Population Segment of the Yellow-billed Cuckoo as Threatened under the Endangered Species Act which would mandate habitat protections. A final decision is expected in 2023.
- Some habitat restoration projects focused on improving riparian woodlands have been implemented on state and private lands that could benefit Yellow-billed Cuckoos.
Cuckoo Identification
Identifying Yellow-billed Cuckoos in the field can be challenging. Here are some tips:
- Look for a slender, long-tailed bird slightly larger than a mourning dove
- Plumage is grayish-brown above and white below
- Flashes rufous outer flight feathers in flight
- Bill is mostly yellowish with some black
- Red eye ring
- Distinctive “kowlp” call sounds like a dove
- Skulking habitat preferences
The Yellow-billed Cuckoo is unlikely to be mistaken for other species when seen well. But it can resemble the Mourning Dove. Focus on the cuckoo’s larger size, longer tail, and yellow bill. Also listen for vocalizations.
Interesting Cuckoo Behaviors
Some interesting behaviors and traits of Yellow-billed Cuckoos include:
- Males and females look identical.
- Nest resembles a flimsy platform of sticks.
- Usually lays 2-3 blue eggs over 2-4 days.
- May remove a host’s egg when laying its own egg.
- Young cuckoos hatch earlier and grow faster than host young.
- Female may lay eggs in multiple nests, not raising any young.
- Often raises two broods per season.
- Young beg aggressively and outcompete host nestlings.
- Host parents feed and care for cuckoo chick as their own.
- Migrates at night in loose flocks.
Brood Parasitism
The Yellow-billed Cuckoo is an obligate brood parasite, meaning it only reproduces by laying eggs in the nests of other species. In Idaho, known hosts include the American Robin, Gray Catbird, Warbling Vireo, and Yellow Warbler.
When a female cuckoo lays an egg in a host’s nest, she removes one of the existing eggs to make room. Amazingly, host birds often fail to notice the substitution and raise the cuckoo chick as their own!
Cuckoo chicks hatch earlier and grow faster than the host chicks. The aggressive cuckoo chick demands most of the food, often pushing out or even killing the other nestlings.
Coexistence with Humans
The Yellow-billed Cuckoo has a reputation as a shy, secretive bird that can be challenging to spot despite its loud calls. It tends to avoid areas of significant human disturbance. Nests are well-hidden in dense foliage.
But cuckoos that nest along Idaho’s rivers and streams may become accustomed to some human presence, especially if adequate buffers of natural habitat remain. Hiking, camping, boating, and other quiet recreational activities are unlikely to negatively impact nesting cuckoos if proper precautions are taken.
Maintaining wide swaths of native vegetation along waterways offers the best protection while also allowing compatible human uses of riparian areas. Therefore, cuckoos can successfully coexist with humans if we make room for them.
Cuckoos and Climate Change
How might climate change affect Yellow-billed Cuckoos in Idaho? Rising temperatures will likely alter river flows, increase droughts, and change riparian plant communities—all of which could impact cuckoo habitat.
If cottonwood galleries shrink, cuckoos may lose nesting sites and become more fragmented. Increased flooding could wash away nests. Prey insects may emerge earlier as springs warm. Any mismatches with cuckoo migration could affect breeding.
Understanding how climate shifts will reverberate through riparian systems is key. Maintaining habitat connectivity will allow cuckoos to move as conditions change. Bolstering populations will boost resilience. Further research will shed more light on future vulnerabilities.
Citizen Science Opportunities
Members of the public can contribute to Yellow-billed Cuckoo conservation in Idaho by participating in citizen science initiatives that track the species:
- The Idaho Birding Trail runs an annual Yellow-billed Cuckoo survey from May to August asking volunteers to listen for cuckoo calls along rivers.
- Cornell Lab of Ornithology’s eBird program documented over 150 Yellow-billed Cuckoo observations from Idaho users in 2022.
- Submitting cuckoo sightings to the Idaho Fish and Wildlife Information System improves data on distribution and habitat use.
- Contacting local conservation groups about volunteering to monitor known cuckoo sites.
- Reporting cuckoo nests to the Idaho Department of Fish and Game helps ensure they are protected.
Conclusion
In conclusion, the Yellow-billed Cuckoo is the only species of cuckoo bird that breeds in Idaho. It is restricted to riparian corridors along the Snake River and some of its major tributaries in the southwestern part of the state. Habitat loss has caused sharp declines, and the species is now endangered in Idaho. But targeted conservation efforts combined with public involvement offer hope for the future. Sustaining healthy river ecosystems will allow Yellow-billed Cuckoos to persist as part of Idaho’s unique natural heritage. While elusive, listening for the distinctive calls of these fascinating brood parasites remains a highlight of a walk along a cottonwood-lined river.