Tree Swallow

Tachycineta bicolor

  • Version: 2.0 — Published June 27, 2011
  • David W. Winkler, Kelly K. Hallinger, Daniel R. Ardia, R. J. Robertson, B. J. Stutchbury, and R. R. Cohen

Free Introduction Article Access

The Introduction Article is just the first of 11 articles in each species account that provide life history information for the species. The remaining articles provide detailed information regarding distribution, migration, habitat, diet, sounds, behavior, breeding, current population status and conservation. Each species account also includes a multimedia section that displays the latest photos, audio selections and videos from Macaulay Library’s extensive galleries. Written and continually updated by acknowledged experts on each species, Birds of North America accounts include a comprehensive bibliography of published research on the species.

A subscription is needed to access the remaining account articles and multimedia content. Rates start at $5 USD for 30 days of complete access.

Subscribe Now

Already a subscriber? Sign In
Figure 1. Breeding and nonbreeding range of the Tree Swallow.

Revised March 1998.

Adult male Tree Swallow, Willington, CT, May.

Adult Tree Swallows can be difficult to sex in the field. Older females look more like adult males, but usually have some dusky grayish feathering in the forehead. This bird has a completely greenish iridescent forehead, typical of adult males. The following is a link to this photographer's website:, May 02, 2009; photographer Mark Szantyr

Juvenile Tree Swallow, Hammonasset Beach SP, CT, 30 August.

Note the plain slaty-brown upperparts lacking the iridescence shown by adults. This bird is yet to begin its complete preformative molt, which takes place from late summer through early winter. The following is a link to this photographer's website:, Jul 09, 2009; photographer Mark Szantyr

Despite its name, the Tree Swallow is a bird of open fields, meadows, and marshes, a species that uses trees only for nesting and occasional roosting. And yet its name is fitting, as no other trait has so singularly distinguished this species as its decision of where to nest. Not diligent builders, Tree Swallows must rely heavily on woodpeckers and other species to excavate and abandon tree cavities in which they can raise their own young. Such cavities are often in short supply, and competition over them has probably shaped much of the breeding ecology and behavior of Tree Swallows, including early spring arrival (Tyler 1942), early breeding and the use of profuse feathers to line the nest (Winkler 1993, Lombardo et al. 1995), intense defense of the nest cavity against conspecifics (Rosvall 2008), and large populations of both male and female floaters (Stutchbury and Robertson 1985).

Researchers long ago discovered that Tree Swallows would readily accept artificial nest boxes. Owing largely to this fact, as well as to the general hardiness and tractability of the species, the Tree Swallow has emerged as something of a model organism in ecology (Jones 2003). Several branches of ecology have benefited from this association, and major advances have been made in the fields of climate change impacts (e.g. Dunn and Winkler 1999), ecotoxicology (see McCarty 2002a), life history theory (e.g. Winkler and Allen 1996, Dunn et al. 2000, Ardia 2005a), mating systems (e.g. Dunn and Hannon 1992, Kempenaers et al. 2001, Whittingham et al. 2006), vertebrate physiology (e.g. Ardia et al. 2003, Haussmann et al. 2005a, Palacios et al. 2007), and behavior (e.g. Stutchbury and Robertson 1987a, Lifjeld et al. 1993, Winkler et al. 2004). As a result, the Tree Swallow stands today as one of the best-studied birds in North America (Jones 2003). Despite this fact, relatively little is known about its migratory or wintering ecology, and studies of breeding populations outside of northeastern North America are sparse.

Recommended Citation

Winkler, D. W., K. K. Hallinger, D. R. Ardia, R. J. Robertson, B. J. Stutchbury, and R. R. Cohen (2011). Tree Swallow (Tachycineta bicolor), version 2.0. In The Birds of North America (A. F. Poole, Editor). Cornell Lab of Ornithology, Ithaca, NY, USA.