Bird house hole size guide

While up to fourty backyard birds are capable of nesting in bird houses, one of the few specifications needed is an exact hole size.

Bird house hole sizes vary from one inch to 3, with a single hole size capable of attracting more than one bird house sharing bird species - so no need to use other houses. While that applies to rounded entrance holes, it can be an open cup. Hole sizes imitate what birds nest in the wild, do don't have to be exact.

To reference size of a bird house hole, it could be you wish to make your own, or need to know what size bird house to buy in order attract a specific species in your yard.

I will say hole size is one of many aspects that come into play when setting up a bird house to attract a Bluebird to a Wren, or a Woodpecker to a Owl.

Help is at hand for hole sizes with my ultimate bird house hole size guide, in which lists all hole sizes needed for up to fourty-three different birds who use bird houses within the United States, and parts of Canada.

To not consider strongly about the importance hole sizes, you'd be quickly proven wrong as birds will come, but you will find its not to their needs.

You see, birds need a specific hole that replicates that of a cavity they nest in a hollow tree - so to be too small or large can deter birds.

I would say though if the hole is a little less or more, it shouldn't really make a difference.

Go ahead then and read up on my guide on bird house entrance hole sizes, beginning with my simple to understand chart of hole sizes, with hole shape coming up next.

Bird house hole size chart

Bird species:	Hole Size:	Hole Shape:	Natural Hole:
Ash-Throated Flycatcher	1-9/16in	Rounded	Cavity
American Kestrel	3in	Rounded	Cavity
American Robin	Open Cup	Rounded	Open
Barn Swallow	Open Half-Cup	Cup	Open
Barn Owl	2-1/2	Rounded	Cavity
Barred Owl	8in	Rounded	Cavity
Barrow's Goldeneye	3-1/2	Rounded	Cavity
Bewick's Wren	1-3/8in	Rounded	Cavity
Black-Capped Chickadee	1-1/8in	Rounded	Cavity
Bufflehead Duck	2-1/2	Rounded	Cavity
Carolina Wren	1-3/8in	Rounded	Cavity
Chestnut-Backed Chickadee	1-1/8	Rounded	Cavity
Common Goldeneye	3-1/2	Square	Cavity
Common Merganser	4 x 5	Square	Cavity
Downy Woodpecker	1-3/8in	Rounded	Cavity
Eastern Bluebird	1-1/2in	Rounded	Cavity
Eastern Phoebe	Open Cup	Cup	Open
Eastern Screech Owl	3in	Rounded	Cavity
Eurasian Tree Sparrow	1-1in	Rounded	Cavity
European Starling	1-5/8	Rounded	Cavity
Great Crested Flycatcher	1-9/16in	Rounded	Cavity
Hairy-Headed Woodpecker	2in	Rounded	Cavity
Hooded Merganser	3 x 4	Square	Cavity
House Finch	1-1/2in	Rounded	Cavity
House Sparrow	1-3/16in	Rounded	Cavity
House Wren	1in	Rounded	Cavity
Juniper Titmouse	1-3/8	Rounded	Cavity
Mountain Bluebird	1-9/16in	Rounded	Cavity
Mountain Chickadee	1-1/8	Rounded	Cavity
Northern Flicker	2-1/2in	Rounded	Cavity
Northern Saw-Whet Owl	2-1/2	Rounded	Cavity
Prothonotary Warbler	1-1/4in	Rounded	Cavity
Purple Martin	2in	Rounded	Cavity
Red-Bellied Woodpecker	1-3/4	Rounded	Cavity
Red-Breasted Nuthatch	1-1/8in	Rounded	Cavity
Red-Headed Woodpecker	1-3/4	Rounded	Cavity
Tree Swallow	1-1/2in	Rounded	Cavity
Tufted Titmouse	1-1/4in	Rounded	Cavity
Violet-Green Swallow	1-3/8	Rounded	Cavity
Western Bluebird	1-9/16in	Rounded	Cavity
Wood Duck	4in	Rounded	Cavity
Wood Thrush	Open Cup	Cup	Open
White-Breasted Nuthatch	1-3/8in	Rounded	Cavity

Specifications chart outlines bird house sizes for up to fourty-three bird species in the United States that use bird houses in backyards.

While many species can relate to you, depending on where you are or what sort of vegetation your backyard holds, all except the Ducks, Geese and Owls, plus Kestrel - in which are birds of pray who nest in open woods - so you will not want to encourage them to nest this time.

Hole size column is a very specific, yet very important dimension in inches to follow.

And while all bird houses need a round hole in the dimensions outlined above, three bird species will only nest in an open cup. Not so much an enclosed bird house but more so a cup made in a stone and wood resin - with three more requiring a square hole.

Not completely relevant but I have taken the courtesy of listing the kind of cavity wild birds in the wild nest in; birds of whom nest in bird houses go inside a cavity, while others in an open open.

Distinction between open and half-cup nest is that half cup is just that, whereas the open cup option is fully rounded.

Duck and geese species featured in table don't nessarily need a rounded hole, but setup of boxes - for owls too - is usually reserved for those who study and look after wild birds.

Bird-specific hole size

What some bird species have in common with the type of bird houses they move into is hole size of course, where style and size of bird house can differ, but just as important.

Focus of the hole size with a bird house for sale or making it yourself is major deciding factor for birds who wish too accept or reject the box you have in the backyard for them.

Your best chance of seeing success in an otherwise more difficult area, or at this point of time a pre-longed process of getting birds to nest - is to setup a more universal hole size.

What that means for you is buying or building a bird house with an entry hole size in one.

That doesn't apply to changing out holes or the entire front of the bird house; it only means to use one hole size on a bird house to attract as many bird species as you can.

Small common backyard birds of America generally take to bird houses with a small entrance hole size, such as Chickadees, Wrens and titmise.

Whereas larger native birds such as Owls and Woodpeckers will happily nest in a bird house with a far larger entrance hole.

Hole size sharing species

What is on your side while attracting birds to nest in your bird house is buying or building a bird house that is capable of encouraging different species to nest in a single box.

Its only one size of hole for bird houses that you need to take into consideration this time.

• 1-1/2 hole size: compatible with that of the Bluebird and Tree Swallow if bird house in question has a floor size of 5 x 5 inches and a hole height of 6 inches
• 1-1/4 hole size: what you really need to consider as it attracts more backyard birds, including Chickadees, Titmouse, Nuthatches, Wrens, and Downy Woodpecker - along with a 4 x 4 inch floor and a 6 inch high entrance hole
• 2-1/2 hole size: can bring Woodpeckers to this size entrance hole bird house: includes Hairy and Red-headed Woodpeckers and the Saw-whet Owl. Build floor at 6 x 6 while making sure hole is positioned 9 inches up
• 3 hole size: largest entry hole of them all, so can attract two birds of pray species: including the Screech-Owl and the American Kestrel, plus the Northern Flicker - Floor size must be 8 x 8 inches with a 13 inch hole height

With all that said and done, bird house sharing species can certainly be happy to nest in box with a hole size that is greater or less than those outlined.

Applies to rounded holes

Whenever I refer to bird house entrance hole sizes I am indeed referring to those using a rounded hole, in which I believe you'll agree is something you can relate too.

Rounded holes on my chart is in reference to more traditional bird houses for different species to use.

Whereas half-cups or open nests can be made with a stone or wood epoxy, but rounded hole bird houses are easier to make - while the availability of bird house styles are plentiful wherever you look to buy.

Bird house holes are basically drilled into wooden bird houses for Bluebirds, Wrens and others - but to be an open cup can be hard to measure.

In all, a cup bird nest made by craftsmen and women vary in widths, and therefore depth.

If you want to bring birds in your yard to nest in a bird house, then I will advice you to only place a bird house with the rounded design.

Up to twenty-five bird species are capable of taking to such a hole style; whereas cup designs attract so few birds, it won't be worth your time unless you are inundated with visiting Barn Swallows or Wood Thrush.

Hole sizes can vary

As much as I, and of course The National Audubon Society can recommend a certain hole size for a specific bird species, sizes can vary so don't always have to be exact.

Bird house entrance holes must be taken seriously regardless, because without species specific sizing the bird house would be open to all birds.

And that can include more invasive species or those that wish to do harm.

Setting up a wrong size hole bird house in an area that requires a smaller hole can therefore attract predators such as squirrels or raccoons in urban areas where eggs are stolen or young birds are killed.

For this reason its important to apply bird specific bird house hole sizes where possible.

However, it is possible to drill out or buy a bird house with a hole size that is a little too big or small - because it really won't make a difference to the birds.

More important to birds is a compact or larger bird house interior, but really all specifications will apply to whether a bird house in your backyard succeeds or not.

Hole replicates nest in the wild

Why a specific hole size is not necessarily required for any bird species is that those holes, or cavities relate to what birds use in the wild.

For example, Eastern Bluebirds natural nesting site would be something in the region of a cavity inside a hollow tree.

Bluebirds would therefore only nest in such a hole that is within their bodies girth, so they can enter and exit with ease, yet feel safe with a hole not to big, but not so small any bird would struggle to get through.

And while that refers to Bluebirds, their nesting habitat can also relate to woodpeckers or any birds who nest in tree cavities.

Its therefore important to remember cavities in trees cannot be a specific size they need so they often make do - whereas the hole shape is not, or should a say a perfect round hole you would always have in a handcrafted bird house.

To be square to triangular would be of concern to birds, but a bird house with a rounded or, or best of - is all that is needed to see birds of all bird houses birds take to your box.

Reject invasive species

To receive interest in your newly put up bird house is nothing new, nor is it new for anyone to only see species nest in their bird house that was never intended for them.

So for that reason do expect different kinds of birds to nest, or at least show interest, but any bird the box is suited to can use it for roosting in cold winter months.

What is a concern that you need to act on is rejecting birds who wish to take up residence in the box, but you could do without - such as non-native birds of America like the House Sparrow.

Sparrows can do horrid, terrible things to the eggs or young so its important they can never enter a bird house intended for say a Bluebird with a 1-1/2 inch hole size.

Hole size of 1-1/2 is for that of Bluebirds and Tree Swallow, so to decrease the hole size from a safe 1-1/2 to 1-1/15 can deter sparrows.

Not a guaranteed safe guard I grant you, but to change the hole size of the bird house can have a little positive effect.

Other methods for rejecting invasive species would be to put the bird house in a location that is undesirable to birds the house is not intended for.

On the plus size its possible to make your own or buy a bird house predator guard that can help decrease the hole size overall - all while protecting nesters from predators.

To summarize

And there you have my ultimate guide to bird house hole sizes, but to save you time let's sum up what you have learned.

But you must refer to or go back to my bird house hole size chart listed on top of my guide whenever you need an exact or close too hole size outlined in inches.

Bird specific bird houses is a real thing and must be closely built to these specification.

To not can see you receive a different, more fussy bird species than the one you intended to attract - or you may end up discourages all birds if its too small or large.

To buy only one bird house can save you money, but when the need to buy a second box crops up; it helps to use a bird house that uses a hole size that can cater up to five bird species in one go.

That is a hole size of 1-1/4 [1.4 in] that is compatible with Chickadees, Titmouse, Nuthatch, Wren, and Downy woodpecker.

And while focus is on wooden bird houses that use a rounded hole of various sizes, my guide refers to resin built nests that use a wide open cup at a specific depth.

Bird house entrance hole sizes can vary from one bird house to the next, and providing its within a respectable margin of error, birds can still take to it.

Most backyard birds nest in hollow tree cavities, so of course its doesn't have to be exact, or else birds will never find a place to live.

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