Cassin's Vireo Life History


Habitat ForestsBreeds in dry, open forests of mountains and foothills.Back to top


Food InsectsArthropods.Back to top


Nest Placement

Nest Tree

Nest Description

Open cup suspended by rim from a fork of a branch of a tree or sapling. Woven of grasses, dead leaves, moss, and hair, decorated with lichen, spider egg cases, cocoons, pieces of wasp nest and paper. Inner lining of grasses, plant fibers, and hair.

Nesting Facts
Clutch Size:2-5 eggs
Egg Description:Whitish with a few brown spots around large end.
Condition at Hatching:Helpless.
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Behavior Foliage GleanerMale performs nest-building display while slightly crouched with body horizontal, usually without nest material in bill.Forages in middle and lower levels of forest. Gleans insects from outer twigs and foliage. Forages in slow and deliberate manner.Back to top


Conservation Low ConcernCassin's Vireo populations slightly increased overall between 1966 and 2015, according to the North American Breeding Bird Survey. Partners in Flight estimates a global breeding population of 4 million with 56% spending some part of the year in the U.S., 92% in Mexico, and 44% breeding in Cananda. The species rates a 10 out of 20 on the Continental Concern Score. Cassin's Vireo is not on the 2016 State of North America's Birds' Watch List. Back to top


Goguen, Christopher B. and David R. Curson. 2002. Cassin's Vireo (Vireo cassinii), version 2.0. In The Birds of North America (P. G. Rodewald, editor). Cornell Lab of Ornithology, Ithaca, New York, USA.

Partners in Flight (2017). Avian Conservation Assessment Database. 2017.

Sauer, J. R., D. K. Niven, J. E. Hines, D. J. Ziolkowski, Jr., K. L. Pardieck, J. E. Fallon, and W. A. Link (2017). The North American Breeding Bird Survey, Results and Analysis 1966–2015. Version 2.07.2017. USGS Patuxent Wildlife Research Center, Laurel, MD, USA.

Sibley, D. A. (2014). The Sibley guide to birds, second edition. Alfred A. Knopf, New York, USA.

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