How elaborate you make your bird house depends on your own tastes. In addition to where you place the box, the most important considerations are: box height, depth, floor dimensions, diameter of entrance hole and height of the hole above the box floor.
Refer to the [following chart] before building your nest box, keeping in mind that birds make their own choices, without regard for charts. So don’t be surprised if you find tenants you never expected in a house you intended for someone else.
Nest Box Dimensions
| Species | Box floor (inches) | Box height (inches) | Entrance height (inches) | Entrance (inches) | Placement diameter height (feet) |
|---|---|---|---|---|---|
| American Robin[1] | 7×8 | 8 | —— | —— | |
| Eastern & Western Bluebirds | 5×5 | 8-12 | 6-10 | 1½ | 4-6 |
| Mountain Bluebird | 5×5 | 8-12 | 6-10 | 1½ | 4-6 |
| Chickadee | 4×4 | 8-10 | 6-8 | 1⅛ | 4-15 |
| Titmouse | 4×4 | 10-12 | 6-10 | 1¼ | 5-15 |
| Ash-throated Flycatcher | 6×6 | 8-12 | 6-10 | 1½ | 5-15 |
| Great Crested Flycatcher | 6×6 | 8-12 | 6-10 | 1¾ | 5-15 |
| Phoebe[1] | 6×6 | 6 | —— | —— | 8-12 |
| Brown-headed/Pygmy/ Red-breasted Nuthatch | 4×4 | 8-10 | 6-8 | 1¼ | 5-15 |
| White-breasted Nuthatch | 4×4 | 8-10 | 6-8 | 1⅜ | 5-15 |
| Prothonotary Warbler | 5×5 | 6 | 4-5 | 1⅛ | 4-8 |
| Barn Swallow[1] | 6×6 | 6 | —— | —— | 8-12 |
| Purple Martin | 6×6 | 6 | 1-2 | 2¼ | 6-20 |
| Tree and Violet-Green Swallows | 5×5 | 6-8 | 4-6 | 1½ | 5-15 |
| Downy Woodpecker | 4×4 | 8-10 | 6-8 | 1¼ | 5-15 |
| Hairy Woodpecker | 6×6 | 12-15 | 9-12 | 1½ | 8-20 |
| Lewis’s Woodpecker | 7×7 | 16-18 | 14-16 | 2½ | 12-20 |
| Northern Flicker | 7×7 | 16-18 | 14-16 | 2½ | 6-20 |
| Pileated Woodpecker | 8×8 | 16-24 | 12-20 | 3×4 | 15-25 |
| Red-Headed Woodpecker | 6×6 | 12-15 | 9-12 | 2 | 10-20 |
| Yellow-bellied Sapsucker | 5×5 | 12-15 | 9-12 | 1½ | 10-20 |
| Bewick’s/House Wrens | 4×4 | 6-8 | 4-6 | 1¼ | 5-10 |
| Carolina Wren | 4×4 | 6-8 | 4-6 | 1½ | 5-10 |
| Barn Owl | 10×18 | 15-18 | 4 | 6 | 12-18 |
| Screech-Owl and Kestrel | 8×8 | 12-15 | 9-12 | 3 | 10-30 |
| Osprey | 48×48 | platform | |||
| Red-tailed Hawk/Great Horned Owl | 24×24 | platform | |||
| Wood Duck | 10×18 | 10-24 | 12-16 | 4 | 10-20 |
[1]Use nesting shelf, platform with three sides and an open front
Now that you have the correct dimensions for your bird house, take a look at how to make it safe: ventilation, drainage, susceptibility to predators, and ease of maintenance.
Ventilation
You should provide air vents in bird boxes. There are two ways to provide ventilation: leave gaps between the roof and sides of the box, or drill ¼ inch holes just below the roof.