Words On Birds by Steve Grinley
Nesting Boxes Aid Cavity-Nesting Birds
April 01, 2017
Many North American birds are cavity-nesters – that is, they nest in holes in trees and fence posts. Woodpeckers can use their strong bills to chisel holes to create their own cavities. Many other birds, such as chickadees, house wrens and titmice must find abandoned cavities in which to nest.
In recent years, birds have had a much tougher time finding adequate natural cavities. Man is too quick to clear timber, especially dead trees, to give woodlots and yard edges a more “pristine look”. As trees are cleared, so are the potential cavities for birds. As land use continues to change in New England, less farm land means fewer fence posts for nesting bluebirds.
An even greater threat to our cavity nesting native birds has been house sparrows and European starlings – birds introduced from Europe, which are also cavity nesters. These aggressive birds have displaced many or our native birds from the few cavities that remain.
One way to solve the housing shortage for our cavity nesting birds is to provide artificial cavities, also known as bird houses or nesting boxes. More than fifty species of birds – including bluebirds, tree swallows, great crested flycatchers, kestrels, chickadees, nuthatches, wrens, kestrels, owls, wood duck and woodpeckers – will use nest boxes. Providing bird houses has enabled many species, including bluebirds, to make dramatic comebacks in our area in recent years. A bird house on your property may provide a cavity nest for birds and some enjoyable bird watching for you.
Bluebirds are already checking out nesting boxes in area towns. They are one of the earlier nesters, often starting their first brood in March or early April. The bright blue male is always a breathtaking sight as he, along with the more subtle colored female, will be going house to house, inspecting for possible occupancy. Soon, they will establish a nesting territory around their chosen home and nest building will begin.
The female bluebird will construct the nest in about five days with little help from the male. The female will also do all the incubation once their four to five eggs are laid – the male has no brood patch. But studies have shown that the male may sometimes “spend the night” in the cavity with the female.
The key to attracting bluebirds to your yard is to have appropriate nest boxes, food and water. Bluebirds prefer more open areas so if your lot is more wooded, other species will be more easily attracted, but probably not bluebirds.
The female will incubate the eggs for a little more than two weeks. She will leave the nest only a few times a day to find food. Once the eggs are hatched, the male bluebird will bring food to the female and young during the first few days.
Bluebirds hunt crawling insects like hawks. They will perch on a stick or fence and wait for an insect to show itself. The bluebird then goes to the ground and pounces on its prey, and brings the food back to the nest.
If you want to attract bluebirds with food, or help them during the nesting process, you can provide mealworms in a feeder near the nesting box. A readily available supply of mealworms will create less stress for the female as she leaves the nest in search of food. It will also help the male provide a more readily available source of nourishment for his mate and offspring. Feeding mealworms will help increase the success rate for nesting bluebirds, as well as other nesting birds in your yard.
The young bluebirds will fledge in fifteen to twenty days. The adult birds will continue to feed the fledglings, though the young will be able to find food on their own in about two weeks. Bluebirds in our area can have two and, sometimes, three broods during the season. So if bluebirds don’t find your house right away, they may choose it for their second brood as late as June. Sometimes, young from the first brood will assist in feeding the young from the second or third brood. This may continue into the fall and the offspring may linger with the adults into the following spring season.
Another key to attracting and keeping bluebirds is to provide water. A heated birdbath may attract them through the winter, and water is always welcome during the warmer months. Planting shrubs and bushes that produce berries also provide a natural food source for bluebirds, especially during the colder months when insects are not available.
Houses, mealworms and water will help to attract bluebirds and other cavity nesting species as spring approaches.
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