Montana Field Guide

The Black-billed Cuckoo is a 31 centimeter-long bird with a stout slightly decurved bill, zygodactyl feet, grayish-brown dorsum, white venter (except tail), and a long tail that is patterned on the underside in gray with white feather tips. The bill is usually all dark, and may show yellow at the base of the lower mandible. There is a reddish eye ring. In juveniles, the undertail is whiter, the eye ring is buffy, the pale underparts may have a buffy tinge, and there may be some rusty-brown color on the outer wing.

For a comprehensive review of the conservation status, habitat use, and ecology of this and other Montana bird species, please see Marks et al. 2016, Birds of Montana.

The Black-billed Cuckoo differs from the Yellow-billed Cuckoo (Coccyzus americanus) by lacking rufous primaries and the absence of an extensively yellow lower mandible.

Summer resident and a nocturnal migrant. Black-billed Cuckoos typically arrive in Montana from early to mid-Jun and depart before October; the earliest sighting was near Alzada on 29 May 1980 and the latest was at the Helena Valley Regulating Reservoir on 27 Sep 1998.

Black-billed Cuckoos are birds of wooded draws, forest edges, thickets, and shelterbelts. In Montana they are found most often in riparian cottonwoods, green ashes, and American elms with a shrubby understory of willows, box elders, and alders; they also occur in foothill deciduous woodlands (Skaar 1969; Walcheck 1969, 1970; Kroodsma 1973; Jones and Hansen 2009).

Diet consists of insects such as caterpillars, crickets, grasshoppers, and butterflies. Also included are mollusks, fish, small vertebrates, fruits and berries.

Raptors the primary predators of adults. In many parts of their range, population fluctuations of Black-billed Cuckoos are related to outbreaks of tent caterpillars and cicadas. BBS data indicate a decline of 15.9% per year in Montana from 1980-2007, but the trend is based on few encounters and is not significant; a significant decline of 3.1% per year occurred survey-wide during the same time period.

Black-billed Cuckoos typically arrive in Montana from early to mid-Jun and probably begin nesting soon thereafter. Few nests have been followed in the state, none in recent years. Typically single-brooded but a second brood may be attempted in the southern breeding range; usually 2-3 eggs laid per clutch. Sometimes a brood parasite; known to parasitize nests of at least 11 species. Incubation period is 10-11 days. Chicks leave nest at 6-7 days after hatching but remain unable to fly for about two more weeks (Hughes 2001). The nest is a well-concealed shallow platform of twigs built in a tree or shrub, often close to the ground. The few nests found in Montana were less than 2 m above ground in buffaloberry, rose, and chokecherry (Bendire 1895, Cameron 1907).

No management activities specific to Black-billed Cuckoo are currently occuring in Montana. In many parts of their range, population fluctuations of Black-billed Cuckoos are related to outbreaks of tent caterpillars and cicadas, which are favored foods. Cuckoos are probably vulnerable to pesticides used to control insect infestations and to the negative effects of overgrazing and fragmentation of riparian habitats (Hughes 2001).

No information for Montana. Frequently killed during migration by flying into television towers, airport ceilometers and tall buildings. Sensitive to forest fragmentation and habitat modification, such as forest understory removal (Hughes 2001).