Sonoma County Nest Box Dimensions Chart
Note: Each species has its own unique nesting criteria, and many factors determine whether or not a bird will use a box. However, it is important to construct the boxes according to the chart dimensions. The entrance hole diameter is critical to a successful nest box.
* Denotes species that reside year-round in Sonoma County.
| Native Bird Species |
Entrance
Hole Diameter (in.) |
Floor Size (in.)
|
Box Height (in.)
|
Entrance Above
Floor (in.) |
Height Above Ground (ft.)
|
| *Barn Owl |
6
|
16 x 20
|
16
|
4
|
15-30
|
| *Northern Sawwhet Owl |
2
|
7 x 7
|
12
|
8-10
|
10-20
|
| *Screech Owl |
3
|
8x8
|
18
|
9-12
|
5-30
|
| *Wood Duck |
3x4 (oval)
|
12x12
|
24
|
12-16
|
5-40
|
| *Downy Woodpecker |
1
|
4x4
|
12
|
6-8
|
5-20
|
| *Hairy Woodpecker |
1
|
6x6
|
14
|
6-8
|
6-20
|
| *Pileated Woodpecker |
4
|
12x12
|
24
|
12-16
|
15-25
|
| *Northern Flicker |
2
|
7x7
|
18
|
14-16
|
6-20
|
| *Chestnut-Backed Chicadee |
1
|
4x4
|
12
|
6-8
|
5-15
|
| *Oak Titmouse |
1
|
4x4
|
12
|
6-8
|
5-15
|
| *White-Breasted Nuthatch |
1
|
4x4
|
12
|
6-8
|
4-20
|
| *Red-Breasted Nuthatch |
1
|
4x4
|
12
|
6-8
|
4-20
|
| *Pigmy Nuthatch |
1
|
4x4
|
12
|
6-8
|
4-20
|
| *Bewick’s Wren |
1
|
4x4
|
12
|
6-8
|
6-10
|
| American Kestrel |
3
|
9x8
|
21
|
9-10
|
15-30
|
| Ash-Throated Flycatcher |
1
|
6x6
|
12
|
6-8
|
6-20
|
| Tree Swallow |
1
|
5x5
|
10
|
2-5
|
3-15
|
| Violet-Green Swallow |
1
|
5x5
|
10
|
2-5
|
3-15
|
| Purple Martin |
2
|
6x6
|
6
|
1
|
12-25
|
| House Wren |
1
|
4x4
|
12
|
2-6
|
6-10
|
| Western Bluebird |
1 9/16
|
5x5
|
12
|
6-7
|
5-10
|
