Measurements
Both Sexes
- Length
- 6.3–7.5 in
16–19 cm - Weight
- 0.8–1.1 oz
24–31 g
Other Names
- Merleblue de l'Ouest (French)
- Azulejo garganta azul (Spanish)
Cool Facts
- Go here to take a look at what goes on inside a Western Bluebird nestbox, through the help of a Nest Box Cam provided by The Birdhouse Network at the Cornell Lab of Ornithology.
- Occasionally Western Bluebirds have helpers at the nest. Most of the extra birds attending nests are helping their presumed parents, some after their own nests have failed.
- Genetic studies showed that 45% of nests had young that were not fathered by the defending male, and that 19% of all the young were fathered outside the pair bond.
- Western Bluebirds can be helped by birds far beyond family members. Violet-green Swallows have been observed feeding and defending nests of Western Bluebirds.
Habitat
Open Woodland
Open coniferous and deciduous woodlands, wooded riparian areas, grasslands, farmlands, and edge and burned areas.
Food
Insects
Insects in summer, fruits and seeds in winter.
Nesting
Nesting Facts
- Clutch Size
- 2–8 eggs
- Egg Description
- Pale blue and unmarked, sometimes white.
- Condition at Hatching
- Naked and helpless with some patches of down.
Nest Description
Nest in cavities in trees and snags, or between bark and trunk. Nest woven of dry grasses, straw, conifer needles, fur, string, or cedar bark strips. Uses nest boxes.
Nest Placement
Cavity
Behavior
Flycatching
Hunts from perches and drops onto ground to catch prey. Some flycatching and gleaning. May beat large prey against ground or branch before eating.
Conservation
Least Concern
Declining in California and Arizona, as well as in other parts of range.
Credits
- Guinan, J. A., P. A. Gowaty, and E. K. Eltzroth. 2000. Western Bluebird (Sialia mexicana). In The Birds of North America, No. 510 (A. Poole and F. Gill, eds.). The Birds of North America, Inc., Philadelphia, PA.