When building a birdhouse or nestbox, the hole size (entrance) is one of the most important decisions you will need to make. Do you know that the diameter of the hole determines which birds will fit into the house and which birds will leave it alone? If the entrance hole is too large you might find less desirable birds are using your birdhouse.
If you are not sure which types of birds you want to attract, go with a larger hole size. This is because birds in general will use a bird house with an entrance hole larger than required. However, the birds will be at more risk from predators such as European starlings which are known for killing nestlings. Learn about the best locations for birdhouse placement and cleaning your birdhouse.
Below are some optimum hole sizes for common cavity nesting birds. That is, birds that build nests and lay eggs inside a cavity or sheltered chamber.
Optimum Birdhouse Hole Size for Cavity Nesting Birds.
| Bird Species | Entrance Hole Size | Entrance Height* | Mounting Height |
| Bluebird | 1.5” (3.8 cm) | 6” (15cm) | 4-6’ (1-2m) |
| Chickadee | 1.25” (3.2cm) | 6” (15cm) | 5-15’ (2-5m) |
| Flicker | 2.5” (6.35cm) | 4” (10cm) | 6-10’ (2-3m) |
| House Finch | 2” (5.1cm) | 4” (10cm) | 5-10’ (2-3m) |
| House Sparrow | 1.75″ (4.5cm) | 6” (15cm) | 10-15’ (3-5m) |
| Kestrel | 3” (7.6cm) | 9” (23cm) | 10-20’ (3-6m) |
| Nuthatches | 1.25” (3.2cm) | 6” (15cm) | 10-15’ (3-5m) |
| Owl | 6” (15cm) | 4” (10cm) | 10-15’ (3-5m) |
| Purple Martin | 2.5” (6.35cm) | 1.5” (3.8cm) | 10-15’ (3-5m) |
| Tree Swallow | 1.5” (3.8cm) | 4” (10cm) | 5-10’ (2-3m) |
| Warbler | 1.25” (3.2cm) | 4” (10cm) | 5-10’ (2-3m) |
| Woodpecker | 1.25” (3.2cm) | 7” (18cm) | 10-20’ (3-6m) |
| Wren | 1.25” (3.2cm) | 4” (10cm) | 6-10’ (2-3m) |
*Entrance Height – location of hole above floor.
One or Two Entrance holes?
Believe it or not, you might want to consider adding more than one entrance hole to your birdhouse. Below are some potential advantages of birdhouses with two entrance holes.
- Both adult birds can feed the young ones at the same time. Otherwise, one adult bird might waste time and energy flying around until the entrance hole is available.
- A second entrance will help avoid the strongest chick dominating access.
- If a predator (such as a snake) gets into the nest, at least the adult birds can escape.
- A second entrance hole helps improve ventilation – allowing better air circulation on warm days.
Where to mount the birdhouse.
To attract nesting birds, it is important to mount or hang the birdhouse in the ideal location. Below are some factors to consider when deciding on where to place a birdhouse.
Birdhouse Location.
Purple martins and bluebirds prefer birdhouses that are in open areas. Most other birds prefer concealed areas that help camouflage the birdhouse. The parents like branches nearby so they can keep an eye over their family.
Birdhouse height.
In general, the higher the bird house the more protection the house provides from cats and other predators. The chart above list the recommended heights for mounting birdhouses for various bird species.
Birdhouse Perch.
Learn the advantages and disadvantages of a Birdhouse perch.
Image Version of Birdhouse Hole Size
Related Articles on Bird Houses, Bird Feeders & More
Use these free DIY bird house plans and bird feeder plans to attract bluebirds, chickadees, flickers, finches, house sparrows, kestrel, nuthatches, owls, purple martins, swallows, thrushes, warblers, woodpeckers, wrens, and other birds to your garden.
Bill and Jodie Rosener | (918) 456-4482 | Tahlequah, OK 74464
About us | Contact us | Privacy Policy | Terms of Use
Thank you, just the information I was looking for.
What size opening and mounting height for a cardinal?
Jan, cardinals are typically not cavity-nesting birds. They prefer to make their nest in the branches of trees rather than in an enclosed space. So making a birdhouse for a cardinal will most likely be in vain. However, the wrens, bluebirds, and sparrows will gladly thank you. Bill
The swallows are pretty but they chase all the other birds away. Last year I had a pair of sparrows and robins nesting in our houses but after the swallows appeared and bothered them the other birds cleaned out the houses and left.
Tree Swallows tho, are great for eating thousands of biting flies.
Those that bite cattle and us. Think of the black, horse and deer flies, they can eat.
is it useful or detrimental to include a perch (dowel or flat surface) outside the hole? if so, how far from the bottom of the hole? Dan
Dan, I believe a perch has more advantages than disadvantages. A perch allows a bird to land when carrying nesting materials and then push the materials inside. A perch also allows a bird to examine its surroundings before entering the birdhouse. I typically place my perch approximately the same distance below the entrance hole as the size of the entrance hole. For example, if the entrance hole is 1.5″, I will place the perch 1.5″ below the entrance hole. Bill
I wanted to build and donate to our local walking trail 10 bird houses I want to do it the most cheapest way but safest for the birds what wood do I use and do I put a water protectant on it as well?? If that project goes well I would like to build more for other area’s. Can anyone help with my question?
Beverly,
I would check out the video on the page Blue Bird Nest Boxes if you are looking for inexpensive birdhouses.
Bill
What type of birdhouse would be suitable for the Eastern Phoebe that would also protect them from Blue Jays? We have several that build under the eaves of our outbuildings, but the Blue Jays have raided several broods.
How often and when should birdhouses be cleaned out?
Thank You for a great website
Be Blessed
John,
Check out the following article on bird house maintenance:
https://suncatcherstudio.com/birds/cleaning-bird-houses/
Thank you,
I was looking for a simple plan for a birdhouse to make for my grandson.
I do not have a workshop, so I wanted something simple I can make in my garage.
I found your site and I like the detailed and simple plans.
I believe I can make a birdhouse now :):)
Thanks again.
Abed Zantout
Sycamore, IL