Bird House Basics

Putting up a bird house (or several) is a great way to learn about the life cycles of your backyard birds. Bluebird pair on a nesting box There is something magical about seeing baby birds in the nest box and watching them take their first flight!  And there are a good number of backyard bird species that are easy to attract to a house.

Nesting sites are one of the 4 main elements birds are looking for in our yards.  (The other three being Food, Water, and Shelter)  Most birds nest in trees, shrubs, on the ground, or under sheltered overhangs.  However, some species of birds are called “cavity nesters”, or birds that prefer to nest in hollowed out cavities in trees.  These are the birds we can attract to bird houses (also called nesting boxes).

These birds that nest in cavities fall under two categories:  primary and secondary cavity nesters.  Primary cavity nesters are birds that create the hollowed out cavities themselves.  These are primarily woodpeckers – birds with chisel-like bills and anatomy suitable for hammering into hard wood.  Secondary cavity nesters are birds that will move into an existing cavity that’s either been created by a woodpecker or has rotted out naturally.

Baby bluebirds in nest boxYou can attract either of these types of cavity nesting birds to nesting boxes – provided you have 3 things:

  1. A suitable habitat for the bird you want to attract
  2. A suitable sized bird house to accomodate the nesting pair and the young
  3. A suitable location within your habitat for your house that the bird prefers.

What are the common backyard birds that will nest in nesting boxes?  There are upwards of 85 species of birds that might use a cavity according to expert Scott Shalaway.  Here are the main ones:

Swallows – Violet Green, Tree, Purple Martin, Cliff (sometimes)

Bluebirds – Mountain, Western, Eastern

Chickadees – Mountain, Carolina, Black-Capped

Nuthatches – White Breasted, Red-Breasted, Brown Headed, Pygmy

Wrens – House, Carolina, Bewicks,

Woodpeckers – Downy, Hairy, Red-Bellied, Red-Headed, Flickers, Pileated

Titmice – Tufted, Plain, Bridled, Black Crested, Juniper, and Oak

Hawks/Owls – Kestrel, Screech Owl, Saw Whet Owl

Ducks – Wood Duck, Bufflehead, Hooded Merganser, Common Goldeneye

Other birds – Prothonotary Warbler, Great Crested Flycatcher, Ash Throated Flycatcher

What Makes A Good Nesting Box?

You can either build a nesting box (if you’re handy with tools) OR buy one pre-built from a store or online.  Whichever way you go, this is not the time to skimp on quality.  Well-made nesting boxes don’t cost a lot more, but will be much better for your birds and will probably last a lot longer.Nesting box bottom with drainage

Here are some guidelines for building or buying a good nesting box:

  • Use wood at least 3/4″ thick.  This insulates the inside better and will last longer.
  • Cedar is the best wood to use since it’s rot and insect resistant.  Pine can be used too.
  • Use woodscrews to put the box together – they hold the house together much better over time.
  • Make sure the roof overhangs the front entrance hole at least 2 inches in the front and at least an inch on the sides.
  • Ensure the entrance hole is just large enough to accomodate the bird you are trying to attract.
  • Having some small drainage holes in the house floor are important to let out excess water.
  • Ventilation openings in the side or front of the box are important in hot climates.
  • The box MUST have a side, front, or roof panel that hinges open.  This is critical for doing nest checks and cleaning out the box.

Note:  We will be publishing on this site nest box size specifications for many of the common cavity nesting birds in the near future. 

 

Where To Place Nesting Boxes

How and where to mount nesting boxes in the yard will depend on the species of bird you are trying to attract.  Each bird species has a particular habitat they need to raise their young and will search for the best location to nest within that area.  For example, bluebirds prefer wide open, grassy locations.  Screech owls like heavily wooded locations high up on the side of a tree.  Wrens prefer scrubby, dense vegetation to nest in.

Bluebird house in school yard

Photo courtesy of the North American Bluebird Society

For many of the birds we want to attract to our gardens and yards, it is best to mount the house on a pole so that the entrance hole is about 5 feet of the ground.  This is because it’s much easier to protect the house from predators on a pole-mounted house.  Climbing predator baffles are very effective at stopping the many kinds of animals in a typical backyard that prey on birds.  Examples here are cats, raccoons, squirrels, and snakes.  In contrast, houses mounted on trees, fences, decks, and sides of buildings can not be easily protected.

Wren houses can usually be hung from trees or crook poles.  These houses have very small entrance holes that most predators have a hard time getting into.  But make sure the house is securely attached to the tree limb and can’t be pulled down easily.

You should place nesting boxes a distance away from bird feeders, your house, and places where there are lots of traffic.  But put it in a place where you can easily see the birds going in and out of the house.

 

Monitoring and Maintaining Your Houses

During the nesting season, it is very important to do nest checks on all of your nest boxes.  This is in order to monitor for any problems such as insect infestation or invasive bird species that may be trying to nest in the house (House Sparrows and Starlings).  Also, it’s a good idea to know which of your houses are successful in attracting birds so you can make changes next nesting season in box location or design.

Note:  some bird houses can be impractical to monitor due to their height off the ground.  Examples are Flicker and Screech Owl houses. 

Monitoring a bluebird box

Photo courtesy of the North American Bluebird Society

Checking nest boxes is easy and it doesn’t disturb the birds.  Nor will it cause them to abandon the nest box.  Just go out to the box once or twice a week, tap on the box to let the parent birds know you’re there, open the box up, take a look inside, note what’s going on, close it back up, and walk away briskly.  It  should only take a minute or two per box.  When looking inside, note the type of nest inside, whether there are any eggs, how many, and what state the young are at.  Also, if there are any unhatched eggs after 3 days or so past when the other birds hatched, they are probably infertile and should be removed.  And it’s a good idea to record your observations, especially if you have multiple nesting boxes.

Nest boxes should be cleaned out after each brood of young fledge.  Old nests are often filled with droppings and insect parasites.  So, just remove the old nest, wash it out with a garden hose, let it dry, and replace the box on the pole.  Some bird species like bluebirds may have more than one brood of young in one nesting season.

In late summer, if your nesting box isn’t being used still (most birds are done by then), you can clean it out and store it away for the winter.  This is also a good time to do any repair work.  If the roof is warped, replace it.   Then, tighten all screws.

 Bluebird Houses

Male eastern bluebird

Photo courtesy of the North American Bluebird Society.

Bluebirds are one of the easiest and most rewarding North American birds you can attract.  They are loved by everyone for their cheerful song, dedicated parenting, and beautiful blue color.  They don’t come to bird feeders much, but will respond to a nesting box readily.

There are 3 species of bluebirds in North America:  the Eastern, Western, and Mountain.  The eastern is the only bluebird found east of the Mississippi.  All bluebirds prefer wide open grassy areas like meadows, golf courses, farm fields, open subdivisions, and ranch land.  As such, you won’t see them in heavily urbanized or dense suburban areas – but pretty much everywhere else.

To attract bluebirds, put up a nest box with a 1 9/16″ diameter entrance hole (this will admit all 3 species), a 3 1/2″ by 3 1/2″ or so size floor, and a 4 1/2″-6″ drop from the hole to the floor.  It should be mounted on a metal pole so the box is about 5 feet off the ground.  And it should have a predator guard of some sort on the pole to prevent animals from climbing up to get at the nest.   Bluebird houses should be put up by January in southern areas of the country and by early March in northern areas.

Bluebirds migrate in some areas of North American, but are year-round residents in others.

Purple Martins

Purple Martin Pair

Photo courtesy of the Purple Martin Conservation Association (www.purplemartin.org)

Purple martins are North America’s largest swallow and are unique in that they nest in colonies.  You can attract them if you live in a generally open area (preferably on the water) and you put up a multiple-compartment nesting colony.  In this case you should buy a pre-made martin house and pole since they are difficult to build correctly.   It’s critical to have houses that can be lowered easily for nest checks.

Purple Martins can also nest in hanging gourds.  In fact, some research has shown these are preferable to the birds.  Artificial plastic gourds are preferable because they last longer and come with closable openings for nest checks and cleanout.

The trick with attracting martins is to initially get your colony established.  This can take some time if Martins are not that numerous in your area.  In the south, especially along or near the Gulf of Mexico, martins are very easy to attract.  The further north you go, the more difficult it can be.  But it’s well worth it.  The chattering chirp of martins and their aerial antics are a treat to watch all summer long.

One of the challenges in starting a successful colony is keeping house sparrows and starlings out of the housing.   Starlings can be excluded with entrance holes they can’t fit through (but martins can).  Sparrows are a bigger challenge, and often need to be trapped to keep them out.

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Cornell Lab of Ornithology