Time to Prepare Nesting Boxes for Spring
March 13, 2010
by Steve Grinley 

Last week I mentioned that bluebirds were already checking out nesting boxes in our area. Putting up man-made bluebird nesting box has enabled bluebird populations to rebound once again. A properly constructed bluebird box, erected on a pole near an open area, may encourage these beautiful birds to nest in your yard. Man-made houses also help other species such as tree swallows, great crested flycatchers and even wood ducks overcome the natural housing shortage.     

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. You may also wash out the box with a mild detergent solution, rinse thoroughly, and let it dry completely. If the entrance hole has been enlarged by squirrels or rodents, 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 you put up if squirrels are a potential problem.  

Migrating robins have also started to arrive. Customers have reported pairs of robins in their yards instead of the larger winter flocks. 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 won’t use a typical bird house, but they may use an open nesting shelf placed on a house, deck, garage or barn.  

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. 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. 

To attract the bird you want, it’s 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 will use a 11/8 inch or 11/4 inch opening while bluebirds, tree swallows and house sparrows need a 11/2 inch 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. For most backyard birds, the house can be placed 5-10 feet off the ground. 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 high, 12-15 feet or more. The house needs to be accessible though, to enable you to discourage house sparrows or starlings from nesting in the house before the martins arrive. Although 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. 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.  

Encouraging birds to nest in your yard by providing nesting boxes is also beneficial to you as well as the birds. Birds can 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 benefit all summer long. Now is the time to ready your nesting 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
BirdWSG@Comcast.net 
978-462-0775 
www.birdwatcherssupplyandgift.com 
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