Tree Swallow

Tachycineta bicolor
STANFORD LOCATIONS:

Uncommon forager around campus from spring through fall, often with flocks of Violet-green and other swallows. Often breeds near water, and perhaps could nest near Lagunita some years, although breeding has not been confirmed on campus.
  
Nest
Location
Nest
Type
Eggs
Mating System
Dev.
Parental Care
Primary &
2ndary Diet
Foraging
Strategy
F
I: 13-16 DAYS
ALTRICIAL
5 feet +
F -M
4-6
MONOG
POLYGYN
F: 20 (16-24) DAYS
MF
BERRIES
FOLIAGE GLEAN
BREEDING: Open country, woodland edge, usu near water. 1 brood, rarely 2.
DISPLAYS: Complex courtship flight.
NEST: In tree hole or other cavity; of grass, often lined with feathers.
EGGS: White, unmarked. 0.8" (19 mm).
DIET: Berries taken when insects unavailable. Occ glean ground.
CONSERVATION: Winters s to Honduras, Nicaragua, and c Costa Rica. Rare cowbird host. Forestry practice of removing standing dead trees has greatly reduced availability of natural nest sites; will use nest boxes.
NOTES: Often nest in loose colonies. Occ polygynous, possibly when food supplies are superabundant. Juveniles often seen as attendants at nonkin nests but do not serve as helpers -- in fact, they attempt to steal food from nestlings and parents! Clutch size larger and nestling survival greater when food very abundant. Hatch asynchronously. Nestlings brooded by female for 5 days. Starlings, House Sparrows, House Wrens, bluebirds compete for nest cavities. Only N.A. passerine in which females do not attain full breeding plumage at one year. Form large premigratory communal roosts; huge flocks perform preroosting aerial displays.
ESSAYS: Cooperative Breeding; Polygyny; Brood Reduction; Variation in Clutch Sizes; Communal Roosting.
REFERENCES: Hussell and Quinney, 1987; Leffelaar and Robertson, 1986; Lombardo, 1987; Quinney, 1986.

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Except for Stanford Locations, the material in this species treatment is taken, with permission, from The Birder's Handbook (Paul Ehrlich, David Dobkin, & Darryl Wheye, Simon & Schuster, NY. 1988).