Montana Field Guide

The Cassin's Kingbird is a large flycatcher with a bright yellow belly, dark gray head and breast, with a white malar. The tail is blackish with pale to whitish tips. The bill, gape, and feet are black (the gape in juveniles is orange). The species is 23 cm in length and has a wingspan of 41 cm (Sibley 2000). As its scientific name implies, this kingbird is noted for its aggressive nature toward potential predators or rivals of its own species, and its obvious and persistent with vocalizations (Tweit and Tweit 2000).

The song of this species is described as clear, nasal notes, containing a hoarse "churr" that rise to sounds of "teew, teew, teew tewdi tidadidew." The call note is described as a husky "CHI-Vrrrr" with nasal notes following in a rapid series (Sibley 2000).

The Cassin's Kingbird is similar in appearance to other yellow-bellied flycatchers, but the only other species known to occur in Montana, and with which it might be confused, is the Western Kingbird (Tyrannus verticalis). The more prominent features separating the two species are the contrasting while malar on the Cassin's cheek and the difference in tail coloration. The Western has a black tail with white outer tail feathers in contrast to the Cassin's blackish tail with a pale tip. The Western Kingbird also has a whitish throat and breast, while the Cassin's is gray. The vocalization of these two species is similar, although the Cassin's is described as lower and less clear than that of the Western Kingbird (Sibley 2000).

Records for Montana indicate the species is not present in the state before May (Montana Bird Distribution 2003). Adults were observed feeding young in July, suggesting that migration does not start until late August, and most likely not until September (Tweit and Tweit 2000, Montana Bird Distribution 2003).

Based upon limited observations in the state, the species is generally restricted to conifer or riparian habitats. Cassin's Kingbird was observed in the relatively open ponderosa pine (Pinus ponderosa) forest near Ashland, in Powder River County, the Bull Mountains, Musselshell County, (a location also dominated by ponderosa pine), and along Cow Creek in the Custer National Forest (Montana Bird Distribution 2003).

Food habit data comes from sources outside the state. These sources state the Cassin's Kingbird feeds primarily on insects (beetles, bees, wasps, caterpillars, moths, etc.) and fruit. Typical foraging is by flying out from a perch and catching prey items in the air, or perching on bushes and vines to pick fruit (Ohlendorf 1971 as cited in Tweit and Tweit 2000).

No ecological information regarding this species exists in Montana. Other studies from areas in the species' range indicate that Cassin's Kingbirds are known to flock in large numbers in the south. The Cassin's Kingbird has been observed in smaller numbers with Western Kingbirds at the start of fall migration in the northern portions of its range (Scott 1993 and Phillips et al. 1964 as cited in Tweit and Tweit 2000).

Ectoparasites include blowflies (Hall 1948 as cited in Tweit and Tweit 2000). Cooper's Hawk (Accipiter cooperi), Great Horned Owl (Bubo virginianus), Common Raven (Corvus corax), Red-tailed Hawk (Buteo jamaicensis), and falcon species (Falco spp.) are known to prey on eggs or chicks. Specific information on predation of adults is not documented.

Of the limited number of breeding records in Montana, one nest was observed with 5 eggs, and two others were known to fledge three young. Egg dates are probably similar to those reported for Colorado: May 24 to July 2. Nest site selection, on at least one occasion, was in an area with relatively high human activity (campground), and another was noted near a riparian area (Cow Creek in Custer National Forest) (Montana Bird Distribution 2003).

No management activities in Montana specific to Cassin's Kingbird are documented.