Western Bluebird house dimensions
The Western Bluebird nests in cavity or nest box A box built to its measurements — and no bigger — is what makes it choose yours.
The specifications
- Entrance hole
- 1 1/2 in
- Floor (inside)
- 5 × 5 in
- Mounting height
- 5–10 ft
- Bird size
- 6.3–7.5 in, 0.9–1.1 oz
- Clutch
- 2–8 eggs
- Incubation
- 12–17 days
- Time in nest
- 19–25 days
- Broods
- 1–2 per season
Build and mounting checklist
- Drill the entrance to exactly 1 1/2 in — oversized holes let in European Starlings and larger predators.
- No outside perch: cavity nesters don't need one, and it helps House Sparrows and predators.
- Unpainted interior, 3/4-inch untreated wood (cedar or pine) or poly-lumber for insulation.
- Drainage holes in the floor corners and ventilation gaps under the roof.
- A side or front panel that opens so you can monitor and clean the box.
- Rough or grooved inner front wall so nestlings can climb out.
- Pole mount with a stovepipe or cone baffle to stop snakes, raccoons and cats.
When to put up a Western Bluebird box, by state
Boxes should be up and clean a month before local nesting starts. Dates shift with latitude:
| Place | Up by | Nesting | Clean out |
|---|---|---|---|
| Arizona | February | March–July | August |
| California | February | March–July | August |
| Colorado | March | April–July | August |
| Idaho | March | April–July | August |
| Nevada | March | April–July | August |
| New Mexico | March | April–July | August |
| Oregon | March | April–July | August |
| Utah | March | April–July | August |
| Washington | March | April–July | August |
| British Columbia | April | May–July | August |
| Montana | April | May–July | August |
Full Western Bluebird species guide →
Frequently asked
What size hole does a Western Bluebird need?
1 1/2 in. A hole cut to this size admits the Western Bluebird (6.3–7.5 in) while keeping out larger competitors.
How big should a Western Bluebird house be inside?
A floor of 5 × 5 in. The Western Bluebird lays 2–8 eggs, so the floor has to hold the full clutch plus growing nestlings.
How high should I mount a Western Bluebird box?
5–10 ft. Mount on a pole with a predator baffle where possible rather than a tree or fence.
How long does a Western Bluebird use the box?
Incubation takes 12–17 days and the young stay in the nest 19–25 days. Broods per year: 1–2 per season.
Sources
- Western Bluebird — All About Birds, Cornell Lab of Ornithology
- Western Bluebird life history — Cornell Lab of Ornithology
- Western Bluebird — Audubon Guide to North American Birds
- NestWatch nest box plans and species requirements — Cornell Lab
Timing reflects typical patterns for the region as a whole; local dates vary with elevation and year. Check the linked eBird bar charts for your county.