Nest box specification

Northern Saw-whet Owl house dimensions

The Northern Saw-whet Owl nests in old woodpecker cavity or nest box in mixed forest A box built to its measurements — and no bigger — is what makes it choose yours.

Owls (Strigidae)Northern Saw-whet OwlAegolius acadicus

The specifications

Entrance hole: 2 1/2 in
Floor (inside): 6 × 6 in
Mounting height: 10–20 ft
Bird size: 7.1–8.3 in, 2.3–5.3 oz
Clutch: 4–7 eggs
Incubation: 27–29 days
Time in nest: 27–34 days
Broods: 1–2 per season

Build and mounting checklist

Drill the entrance to exactly 2 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 Northern Saw-whet Owl 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
California	January	February–June	July
Colorado	February	March–June	July
Connecticut	February	March–June	July
Idaho	February	March–June	July
Massachusetts	February	March–June	July
Michigan	February	March–June	July
Nevada	February	March–June	July
New Jersey	February	March–June	July
New York	February	March–June	July
Oregon	February	March–June	July
Pennsylvania	February	March–June	July
Rhode Island	February	March–June	July
Utah	February	March–June	July
Washington	February	March–June	July
Alaska	March	April–June	July
Alberta	March	April–June	July
British Columbia	March	April–June	July
Maine	March	April–June	July
Manitoba	March	April–June	July
Minnesota	March	April–June	July
Montana	March	April–June	July
New Brunswick	March	April–June	July
New Hampshire	March	April–June	July
Newfoundland and Labrador	March	April–June	July
Northwest Territories	March	April–June	July
Nova Scotia	March	April–June	July
Ontario	March	April–June	July
Prince Edward Island	March	April–June	July
Quebec	March	April–June	July
Saskatchewan	March	April–June	July
Vermont	March	April–June	July
Wisconsin	March	April–June	July
Wyoming	March	April–June	July
Yukon	March	April–June	July

Full Northern Saw-whet Owl species guide →

Frequently asked

What size hole does a Northern Saw-whet Owl need?

2 1/2 in. A hole cut to this size admits the Northern Saw-whet Owl (7.1–8.3 in) while keeping out larger competitors.

How big should a Northern Saw-whet Owl house be inside?

A floor of 6 × 6 in. The Northern Saw-whet Owl lays 4–7 eggs, so the floor has to hold the full clutch plus growing nestlings.

How high should I mount a Northern Saw-whet Owl box?

10–20 ft. Mount on a pole with a predator baffle where possible rather than a tree or fence.

How long does a Northern Saw-whet Owl use the box?

Incubation takes 27–29 days and the young stay in the nest 27–34 days. Broods per year: 1–2 per season.

Sources

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.