Yellow-billed Cuckoos use wooded habitat with dense cover and water nearby, including woodlands with low, scrubby, vegetation, overgrown orchards, abandoned farmland, and dense thickets along streams and marshes. In the Midwest, look for cuckoos in shrublands of mixed willow and dogwood, and in dense stands of small trees such as American elm. In the Southwest, Yellow-Billed Cuckoos are rare breeders in riparian woodlands of willows, cottonwoods and dense stands of mesquite to breed. Back to top
Caterpillars top the list of Yellow-Billed Cuckoo prey: individual cuckoos eat thousands of caterpillars per season. On the East coast, periodic outbreaks of tent caterpillars draw cuckoos to the tentlike webs, where they may eat as many as 100 caterpillars at a sitting. Fall webworms and the larvae of spongy (formerly gypsy), brown-tailed, and white-marked tussock moths are also part of the cuckoo’s lepidopteran diet, often supplemented with beetles, ants, and spiders. They also take advantage of the annual outbreaks of cicadas, katydids, and crickets, and will hop to the ground to chase frogs and lizards. In summer and fall, cuckoos forage on small wild fruits, including elderberries, blackberries and wild grapes. In winter, fruit and seeds become a larger part of the diet.Back to top
Pairs may visit prospective nest sites multiple times before building a nest together. Nest heights can range from 3 feet to as much as 90 feet off the ground, with the nest placed on a horizontal branch or in the fork of a tree or large shrub. In the central and eastern U.S., Yellow-billed Cuckoos nest in oaks, beech, hawthorn, and ash. Pine, juniper, and fir are used less frequently. In the West, nests are often placed in willows along streams and rivers, with nearby cottonwoods serving as foraging sites.
The male and female Yellow-Billed Cuckoo build a loose stick nest together, using twigs collected from the ground or snapped from nearby trees and shrubs. They construct a flat, oblong platform reaching up to 5 inches deep and 8 inches in diameter. The pair may line the nest sparingly with strips of bark or dried leaves. The finished nest cup is about 5 inches across and 1.5 inches deep. The male sometimes continues bringing in nest materials after incubation has begun.
|Clutch Size:||1-5 eggs|
|Number of Broods:||1-2 broods|
|Egg Length:||1.1-1.4 in (2.7-3.6 cm)|
|Egg Width:||0.8-1.0 in (2.1-2.5 cm)|
|Incubation Period:||9-11 days|
|Egg Description:||Smooth, unmarked, pale bluish-green fading to light greenish yellow.|
|Condition at Hatching:||Chicks are born naked but are alert and active within 10 minutes of hatching; they become partly covered in pin feathers within 24 hours, with one or both eyes open.|
Yellow-Billed Cuckoos are patient feeders, sitting motionless on hidden perches, often with shoulders hunched to disguise their white chest and belly as they wait for prey to move. They glean insects from leaves and may hop to the ground to chase lizards, frogs and grasshoppers, or sally out like a flycatcher to grab a flying insect. Caterpillars are a favorite prey item: the cuckoo will roll a caterpillar back and forth through its bill, perhaps to try and strip off some of the spiny hairs. Cuckoos may respond to available food supplies rather than a set season to begin breeding. A receptive female perches with its head up, pumping its tail slowly up and down in a 180-degree arc. Just prior to mating, the male Yellow-Billed Cuckoo snaps off a short twig that he presents to the female as he perches on her back and leans over her shoulder. Both birds then grasp the twig as they copulate. When they do leave a sheltered perch, the Yellow-Billed Cuckoo’s flight is swift and direct, with deep beats of their long pointed wings.Back to top
Yellow-billed Cuckoo populations declined approximately 0.8% per year for a cumulative decline of about 34% between 1966 and 2019, according to the North American Breeding Bird Survey. Partners in Flight estimates the global breeding population at about 9.6 million and rates them 12 out of 20 on the Continental Concern Score, indicating a species of relatively low conservation concern. However, it is included on the list of Common Birds in Steep Decline, for species that are too numerous or widely distributed to warrant Watch-List status but have been experiencing troubling long-term declines. In the West, much of the Yellow-Billed Cuckoo’s riparian habitat has been converted to farmland and housing, leading to significant population declines and the possible extirpation of cuckoos from British Columbia, Washington, Oregon, and Nevada. Once common in the California’s Central Valley, coastal valleys, and riparian habitats east of the Sierra Nevada, habitat loss now constrains the California breeding population to small numbers of birds along the Kern, Sacramento, Feather, and Lower Colorado Rivers. The western population of Yellow-billed Cuckoos is a candidate for federal endangered status. Sites replanted with riparian vegetation in southern California supported breeding birds within three years, demonstrating the potential for habitat restoration. One of the few birds that can digest the hairy spines of the spongy moth caterpillar (formerly gypsy moth), local populations have benefitted where outbreaks of this pest have occurred. As long-distance, nocturnal migrants, Yellow-Billed Cuckoos are vulnerable to collisions with tall buildings, cell towers, radio antennas, wind turbines, and other structures.Back to top
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