Words On Birds by Steve Grinley

Prepare Bird Houses for Spring Occupancy
March 16, 2019
By Steve Grinley

     Last week I mentioned that bluebirds were already checking out nesting boxes in our area. Putting up bluebird nesting boxes has enabled bluebird populations to rebound once again. Man-made houses also help other bird species such as tree swallows, chickadee nuthatches and titmice overcome the natural housing shortage. In fact, most cavity nesting birds will take to a nesting box if it is properly built and placed in the right habitat.

     March is a good time to inspect, clean and repair any existing birdhouses that you have. Clean out any old nesting material and brush out the inside walls with a wire brush. If the entrance hole has been enlarged by squirrels or other critters, you can add a new wood predator guard over the hole to reduce the hole size again. Metal guards can be placed over holes to prevent future chewing. Metal guards may be a good idea on any new houses that you put up if squirrels are a potential problem.

     Also remember that not all birds will nest in a house. Only those birds that naturally nest in tree cavities will use a nesting box. Every year we are asked for houses for cardinals or goldfinches. These, like so many birds, build their nests on limbs of trees or in dense shrubs and will not nest in a house.

     Where you live and the type of habitat that you have in your yard will be determining factors in which birds you may be able to attract. If you live in a densely populated area, house sparrows, house finches and starlings are likely nesting candidates but robins, chickadees or house wrens may also be possible. Bluebirds, tree swallows and purple martins prefer open areas, house wrens like brushy edge areas, while chickadees, nuthatches and titmice prefer more wooded areas.

     To attract the bird you want, it is best to start with a birdhouse that is built to specification for that bird and place it in a suitable area. The entrance hole size is one critical dimension. House wrens, for instance, can squeeze into a 1 inch opening that will eliminate most larger birds. Chickadees, titmice, nuthatches and downy woodpeckers require at least a 1 1/8” or 1 1/4” opening while bluebirds, tree swallows and house sparrows need a 11/2” opening.

     For birds that compete for the same size house, such as bluebirds and tree swallows, placing two houses close to each other may allow them to nest side by side. Houses can be spaced 20-50 feet apart to attract different species. Houses for the same species, however, should be spaced at least 100-200 feet apart. This is because most birds are very territorial within their species and won’t allow another bird of the same species to nest nearby. The house should be mounted five to ten feet off the ground for most backyard birds. Face the houses away from northerly directions as cold wind and rain can be detrimental to newly hatched, featherless young in early spring.

     Purple martins nest in colonies and need an open area, preferably with water nearby. Their apartment houses should be erected higher, 12-15 feet or more. The house needs to be accessible though, to enable you access to discourage house sparrows or starlings from nesting in the house before the martins arrive. Though purple martin “scouts” arrive in mid-April, it is the first year young arriving with females in early May that are usually looking for new housing. Some will find nest sites as late as mid June. Attracting purple martins requires much more work initially than attracting some other birds, but once martins establish their colony, they will return faithfully each year. In fact, may birds such as bluebirds, tree swallows and nuthatches, return to the same nest site each year.

     Migrating robins have also started to arrive. Phoebes will arrive in a couple of weeks and barn swallows return in April. These three birds have adapted to man by often nesting on ledges of man-made structures. They will not use a typical bird house, but they may use an open nesting shelf placed on a house, deck, garage or barn.

     Encouraging birds to nest in your yard by providing nesting boxes and nesting shelves is also beneficial to you as well as the birds. Birds help control the insect populations on your lawn, in your garden and on your shrubs without the use of harmful chemicals. Houses erected for purple martins, tree and barn swallows, crested flycatchers and phoebes help control flying insects, while many other species such as wrens, bluebirds and woodpeckers eat crawling insects. This natural insect control will be a residual benefit to you all summer long.

     Now is the time to ready your nest boxes or put up new ones, before the birds, and the insects, arrive.

Steve Grinley
Bird Watcher’s Supply & Gift
Route 1 Traffic Circle
194 Route 1
Newburyport, MA 01950
Celebrating 2
4 years of service to the birding community! 
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