ABOUT THE BLUEBIRD (Sialia mexicana)
A Few Facts
The Western Bluebird (Sialia mexicana), a songbird, is a small thrush, approximately 5.9” to 7.1” in length . They
are voracious consumers of insects, and, because they don’t eat fruit, can be an important growing and gardening
partner. The Mountain Bluebird, not discussed here, is also seen in Northern California, generally found at elevations
above 5,000 feet.
Description
Adult males are bright blue on top and throat with orange breast and sides, a brownish patch on back, and a gray
belly and undertail coverts. Adult females have a duller blue body, wings, and tail than the male, a gray throat, dull
orange breast, and a gray belly and undertail coverts. There is no difference in size. Immature Western Bluebirds have
duller colors than the adults, they also have spots on their chest and back.
Habitats
The Western Bluebird is found year-round in California. They nest in natural cavities, competing for nesting space
with the Common Starling,American Crow and House Sparrow. The nest if often exposed to predators like cats, snakes
and raccoons. Thanks to increasing deployment of nesting boxes, the population is increasing; eggs are laid earlier, more
young are fledged and predation rates are lower.
Diet
Bluebirds are generalized insect feeders, consuming Blue/Green Sharpshooters as well as caterpillars, beetles and
grasshoppers off of vines, on the ground or elsewhere. A bluebird family of five nestlings requires 125 grams of
arthropods per day. Greatest feeding is March to July, ideal for controlling insects in the garden or vineyard.
Breeding
Bluebirds produce two or more broods per year with 4-6 eggs/clutch, typically during the spring and summer. Males
identify nest sites, place some material in the potential nest and then attract prospective female mates with singing and
flapping wings. If the female accepts the male and the nesting site, she builds the nest and incubates the eggs.
Results of Deploying Bluebird Boxes
A large St. Helena, California vineyard had been invaded by the blue-green sharpshooter. In 2007, they installed
hundreds of houses throughout the vineyards. By 2010, the By 2010, the vineyard was virtually sharpshooter free.
Separately, studies have found 10 times as many bluebirds in areas with bluebird boxes, and 3.5 times as many sharp-
shooters where no nesting boxes in area.
Mounting Nesting Boxes - General
Mount on smooth metal or PVC poles from 4’ to 15’ above ground, spaced at intervals of about 200’-300’ apart and
away from wooded area. Set out two boxes if 10’ apart if swallows a problem. They’ll share.
Direct entrance hole away from prevailing winds to reduce the amount of rain that might be blown into the box, faced
away from direct sun exposure.
Nearby trees provide young bluebirds both with a place to fly to when they first leave the nest, as well as shelter
from the elements and predators. Boxes mounted along roads should always face parallel with the road.
Mounting the Amador Barn Owl Box Co Bluebird Box
Note that the back wall of the box extends above and below the main
body of the box to enable easy mounting using screws.
More Information
For more information on Bluebird Boxes and/or the Bluebird, ask your local Retailer, go to web sites like
http://www.bluebirdsforever.com/houses.html, and feel free to contact the Amador Barn Owl Box Company directly.
A Few Facts
The Western Bluebird (Sialia mexicana), a songbird, is a small thrush, approximately 5.9” to 7.1” in length . They
are voracious consumers of insects, and, because they don’t eat fruit, can be an important growing and gardening
partner. The Mountain Bluebird, not discussed here, is also seen in Northern California, generally found at elevations
above 5,000 feet.
Description
Adult males are bright blue on top and throat with orange breast and sides, a brownish patch on back, and a gray
belly and undertail coverts. Adult females have a duller blue body, wings, and tail than the male, a gray throat, dull
orange breast, and a gray belly and undertail coverts. There is no difference in size. Immature Western Bluebirds have
duller colors than the adults, they also have spots on their chest and back.
Habitats
The Western Bluebird is found year-round in California. They nest in natural cavities, competing for nesting space
with the Common Starling,American Crow and House Sparrow. The nest if often exposed to predators like cats, snakes
and raccoons. Thanks to increasing deployment of nesting boxes, the population is increasing; eggs are laid earlier, more
young are fledged and predation rates are lower.
Diet
Bluebirds are generalized insect feeders, consuming Blue/Green Sharpshooters as well as caterpillars, beetles and
grasshoppers off of vines, on the ground or elsewhere. A bluebird family of five nestlings requires 125 grams of
arthropods per day. Greatest feeding is March to July, ideal for controlling insects in the garden or vineyard.
Breeding
Bluebirds produce two or more broods per year with 4-6 eggs/clutch, typically during the spring and summer. Males
identify nest sites, place some material in the potential nest and then attract prospective female mates with singing and
flapping wings. If the female accepts the male and the nesting site, she builds the nest and incubates the eggs.
Results of Deploying Bluebird Boxes
A large St. Helena, California vineyard had been invaded by the blue-green sharpshooter. In 2007, they installed
hundreds of houses throughout the vineyards. By 2010, the By 2010, the vineyard was virtually sharpshooter free.
Separately, studies have found 10 times as many bluebirds in areas with bluebird boxes, and 3.5 times as many sharp-
shooters where no nesting boxes in area.
Mounting Nesting Boxes - General
Mount on smooth metal or PVC poles from 4’ to 15’ above ground, spaced at intervals of about 200’-300’ apart and
away from wooded area. Set out two boxes if 10’ apart if swallows a problem. They’ll share.
Direct entrance hole away from prevailing winds to reduce the amount of rain that might be blown into the box, faced
away from direct sun exposure.
Nearby trees provide young bluebirds both with a place to fly to when they first leave the nest, as well as shelter
from the elements and predators. Boxes mounted along roads should always face parallel with the road.
Mounting the Amador Barn Owl Box Co Bluebird Box
Note that the back wall of the box extends above and below the main
body of the box to enable easy mounting using screws.
- Flat against the side of a structure, tree, fence or square
wooden pole - On top of a flat section of fence, or pole
More Information
For more information on Bluebird Boxes and/or the Bluebird, ask your local Retailer, go to web sites like
http://www.bluebirdsforever.com/houses.html, and feel free to contact the Amador Barn Owl Box Company directly.
