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Montana Field Guide

Montana Field Guides

Cassin's Kingbird - Tyrannus vociferans

Potential Species of Concern
Native Species

Global Rank: G5
State Rank: S4B

Agency Status

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Copyright by Borror Laboratory of Bioacoustics, Department of Evolution, Ecology, and Organismal Biology, Ohio State University, Columbus, OH, all rights reserved.
General Description
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 it is 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).

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.

Diagnostic Characteristics
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 Kingbird cheek and the difference in tail coloration. The Western Kingbird has a black tail with white outer tail feathers in contrast to the Cassin's Kingbird's blackish tail with a pale tip. The Western Kingbird also has a whitish throat and breast, while the Cassin's Kingbird is gray. The vocalization of these two species is similar, although the Cassin's Kingbird is described as lower and less clear than that of the Western Kingbird (Sibley 2000).

Species Range
Montana Range Range Descriptions

All Ranges
(Click legend blocks to view individual ranges)

Western Hemisphere Range


Observations in Montana Natural Heritage Program Database
Number of Observations: 450

(Click on the following maps and charts to see full sized version) Map Help and Descriptions
Relative Density


SUMMER (Feb 16 - Dec 14)
Direct Evidence of Breeding

Indirect Evidence of Breeding

No Evidence of Breeding

WINTER (Dec 15 - Feb 15)
Regularly Observed

Not Regularly Observed


(Observations spanning multiple months or years are excluded from time charts)

Records for Montana indicate the species is not present in the state before May (Lenard at al. 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 Committee 2012).

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 Committee 2012).

Ecological Systems Associated with this Species
  • Details on Creation and Suggested Uses and Limitations
    How Associations Were Made
    We associated the use and habitat quality (common or occasional) of each of the 82 ecological systems mapped in Montana for vertebrate animal species that regularly breed, overwinter, or migrate through the state by:
    1. Using personal observations and reviewing literature that summarize the breeding, overwintering, or migratory habitat requirements of each species (Dobkin 1992, Hart et al. 1998, Hutto and Young 1999, Maxell 2000, Foresman 2012, Adams 2003, and Werner et al. 2004);
    2. Evaluating structural characteristics and distribution of each ecological system relative to the species' range and habitat requirements;
    3. Examining the observation records for each species in the state-wide point observation database associated with each ecological system;
    4. Calculating the percentage of observations associated with each ecological system relative to the percent of Montana covered by each ecological system to get a measure of "observations versus availability of habitat".
    Species that breed in Montana were only evaluated for breeding habitat use, species that only overwinter in Montana were only evaluated for overwintering habitat use, and species that only migrate through Montana were only evaluated for migratory habitat use.  In general, species were listed as associated with an ecological system if structural characteristics of used habitat documented in the literature were present in the ecological system or large numbers of point observations were associated with the ecological system.  However, species were not listed as associated with an ecological system if there was no support in the literature for use of structural characteristics in an ecological system, even if point observations were associated with that system.  Common versus occasional association with an ecological system was assigned based on the degree to which the structural characteristics of an ecological system matched the preferred structural habitat characteristics for each species as represented in scientific literature.  The percentage of observations associated with each ecological system relative to the percent of Montana covered by each ecological system was also used to guide assignment of common versus occasional association.  If you have any questions or comments on species associations with ecological systems, please contact the Montana Natural Heritage Program's Senior Zoologist.

    Suggested Uses and Limitations
    Species associations with ecological systems should be used to generate potential lists of species that may occupy broader landscapes for the purposes of landscape-level planning.  These potential lists of species should not be used in place of documented occurrences of species (this information can be requested at: or systematic surveys for species and evaluations of habitat at a local site level by trained biologists.  Users of this information should be aware that the land cover data used to generate species associations is based on imagery from the late 1990s and early 2000s and was only intended to be used at broader landscape scales.  Land cover mapping accuracy is particularly problematic when the systems occur as small patches or where the land cover types have been altered over the past decade.  Thus, particular caution should be used when using the associations in assessments of smaller areas (e.g., evaluations of public land survey sections).  Finally, although a species may be associated with a particular ecological system within its known geographic range, portions of that ecological system may occur outside of the species' known geographic range.

    Literature Cited
    • Adams, R.A.  2003.  Bats of the Rocky Mountain West; natural history, ecology, and conservation.  Boulder, CO: University Press of Colorado.  289 p.
    • Dobkin, D. S.  1992.  Neotropical migrant land birds in the Northern Rockies and Great Plains. USDA Forest Service, Northern Region. Publication No. R1-93-34.  Missoula, MT.
    • Foresman, K.R.  2012.  Mammals of Montana.  Second edition.  Mountain Press Publishing, Missoula, Montana.  429 pp.
    • Hart, M.M., W.A. Williams, P.C. Thornton, K.P. McLaughlin, C.M. Tobalske, B.A. Maxell, D.P. Hendricks, C.R. Peterson, and R.L. Redmond. 1998.  Montana atlas of terrestrial vertebrates.  Montana Cooperative Wildlife Research Unit, University of Montana, Missoula, MT.  1302 p.
    • Hutto, R.L. and J.S. Young.  1999.  Habitat relationships of landbirds in the Northern Region, USDA Forest Service, Rocky Mountain Research Station RMRS-GTR-32.  72 p.
    • Maxell, B.A.  2000.  Management of Montana's amphibians: a review of factors that may present a risk to population viability and accounts on the identification, distribution, taxonomy, habitat use, natural history, and the status and conservation of individual species.  Report to U.S. Forest Service Region 1.  Missoula, MT: Wildlife Biology Program, University of Montana.  161 p.
    • Werner, J.K., B.A. Maxell, P. Hendricks, and D. Flath.  2004.  Amphibians and reptiles of Montana.  Missoula, MT: Mountain Press Publishing Company. 262 p.

Food Habits
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 (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 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.

Reproductive Characteristics
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 Committee 2012).

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

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Citation for data on this website:
Cassin's Kingbird — Tyrannus vociferans.  Montana Field Guide.  .  Retrieved on , from