Birds that Use Nest Boxes
October 25th, 2022 by georgann
Over thirty species of North American birds nest in cavities; ten of them are common in the southeastern U.S.–Carolina and House Wrens, Tufted Titmice, Carolina Chickadees, Brown-headed and White-breasted Nuthatches, Eastern Bluebirds, Tree Swallows, Great Crested Flycatchers, and Eastern Screech-Owls. The entrance holes of the wrens, nuthatches, chickadee and titmouse can be as small as one inch. Holes of bluebirds and swallows should be at least 1.5 inches. Great Crested Flycatchers and Eastern Screech-Owls use a three inch entrance hole.
Carolina Wrens (Thryothorus ludovicianus) are feisty small brown birds that nervously dart about often with their tail pointing straight upwards. Wrens are friendly and will nest in any suitable cavities, nooks or crannies around buildings. They often prefer unusual places such as hanging flower baskets, wreaths hanging on doors, or even paper bags and boxes left in an open garage. Since they are opportunistic, they are not fussy about the dimensions or the placement of your bird box. Their nest is a bulky mass of leaves, twigs, mosses, rootlets and generally built with a side entrance. The 4-8 eggs are white to pale pink heavily marked with fine reddish-brown stippling, forming a wreath at the larger end.
House wrens (Troglodytes aedon) look much like Carolina Wrens but without the white eyeline. Known to nest readily in boxes, they actually prefer an entrance hole that is elliptical. House Wrens use small 3 inch sticks in their nest and can more easily fit these through an elongated entrance hole rather than a round hole. As with most other birds previously discussed above, House Wrens prefer their box to be placed about 5 feet above the ground, facing an open area. The 5-8 white eggs are thickly speckled with reddish stipples covering the entire egg. House Wrens are known to destroy nests, eggs and young of other birds using boxes.
Tree Swallows (Tachycineta bicolor) are becoming a more common breeding bird in the southeastern states. Their beautiful iridescence of blue/green back contrasts with a white underbelly. They often compete with Eastern Bluebirds for boxes. The nest is made of dry grasses and almost always lined with feathers often placed so their curved tips curl over the eggs
The small gray Tufted Titmouse (Baeolophus bicolor) uses abandoned woodpecker holes and natural cavities in tree trunks or limbs. However, they will readily come to your bird box. In fact, they are often the first birds to investigate it and move in. As with other users of nesting boxes, they prefer a box approximately 5 feet off the ground that is securely fastened to a post or tree trunk. Their delicate nest is made of grass, leaves, bits of string or cloth and padded with hair and moss. 4-8 eggs are white and evenly speckled with small spots, often concentrated at the large end.
Carolina Chickadees (Poecile carolinensis) share similar requirements as Tufted Titmice. In addition, both species are easily attracted to sunflower seed and bird feeders. They construct their nests of soft materials, moss and fuzz. Small gathered pieces of moss, soft dog or cat hairs, or 2 inch segments of yarn may be placed near a box. You will know if they used your proffered items in the fall when you remove and discard the old nest from the box. Their nest construction and eggs resemble those of the Tufted Titmouse.
Brown-headed Nuthatches (Sitta pusilla) and White-breasted Nuthatches (Sitta carolinensis) can be difficult birds to attract to a man-made bird house. They prefer to nest as high as 30 feet. You can increase your chances by placing your box as high as possible. Nuthatches are a delight to watch as they creep up and down tree trunks grabbing insects from under the edges of the tree bark. Both species construct nests of bark shreds, twigs, grasses, rootlets, fur and feathers. The eggs of the White-breasted Nuthatch are less marked with dots than those of the Brown-headed Nuthatch. Both lay 5-10 eggs.
Of all the birds that people wish to attract to a bird box, the Eastern Bluebird (Sialia sialis) ranks perhaps the highest. Bluebirds experienced a severe population decline from the 1930’s to the 1970’s. Being insectivores, these birds were eating the pesticides (notably DDT) used to kill insects. With the destruction of woodlands and removal of dead trees, they were further pressured by loss of nesting cavities. Although we still use pesticides that often threaten wildlife, the practice of constructing bluebird trails and the use of bird boxes has returned the Eastern Bluebird to stable populations. Bluebirds prefer a box that has its back to the woods and faces a large open area. Their entrance hole should be l-l/2 inches. European Starlings and House Sparrows will try to nest in bluebird boxes. Careful monitoring and removal of starling and sparrow nests will insure that your bluebirds will successfully nest in your box. Bluebirds usually lay 3-5 pale blue eggs placed in a nest constructed of pine straw or grasses.
Great Crested Flycatchers (Myiarchus crinitus) are birds of middle to high canopy appearing in North America only in the summer breeding months. They are sometimes heard more often than seen, calling a loud uprising, “wheep”. This is a large flycatcher and is usually found nesting in cavities of woodpeckers and rotten stumps, but will choose boxes that have been put out for Eastern Screech-Owls. The bulky nest is made of twigs, leaves, hair, feathers and bark fibers. It almost always includes a snake-skin or piece of cellophane or plastic strip. The 4-8 eggs are pinkish white with dense scratches, streaks and blotches of dark brown.
Everyone wants an Eastern Screech-Owl (Otus asio) to nest in their yard even though it is a predator of other birds. Hearing their whinny calls at night and watching both parents feeding their young before and after they have left the nest is are a thrill. Most often choosing natural sites, these little owls may take a while to find a box, but one established may remain in the area for many years. No nest is built in the box, but there may be a natural accumulation of twigs or leaves carried in by squirrels. Generally 2-6 eggs are laid and incubated for 21-30 days. The nestling period is about the same period of time, so a nest with eggs in early April will fledge young by early June.
PLACEMENT OF YOUR BIRD BOX
When
In the southeast, cavity nesting birds begin searching for suitable nest sites as early as February. (Eastern Screech-Owl boxes should be in place in late fall in order for them to find and move in during the winter months.) If you removed your box during the winter, place it out again by early February. Watch for activity around the box. Usually the male of the species inspects the house first and then tries to “sell” it to his mate. In many cases, she will not care for the first box he shows her. Putting out two or more boxes for her to choose from will increase your chances of successful nesting. However, you will not get more than one pair of the same species nesting close together. For example, Eastern Bluebirds prefer to nest 75-100 yards apart.
Where
As discussed above, placement of the box may be more important than dimensions and entrance hole size. Some species prefer an open area (bluebirds and swallows) while others are more likely to choose a box in a wooded lot (titmice, chickadees, nuthatches, flycatchers and owls). If your nest box is not successful by mid-May, try moving it to another site. Don’t give up–birds may take a year or two to find and choose your box.
When attaching your box to a tree trunk or post, nail it securely at the top and bottom. Birds rarely nest in boxes that swing or move around. The direction in which the box faces is debatable, but it appears that east and southeast are best. Your box should be hung five feet above the ground in order to attract the most species and make it easy to maintain. However, Great Crested Flycatchers, Brown-headed Nuthatches and Eastern Screech-Owl prefer boxes hung from 15 to 20 feet.
MAINTENANCE OF YOUR BIRD BOX
If your bird box is made of cypress, cedar or redwood it is naturally rot-resistant and will not need further treatment. Other types of wood can be used, but avoid any treated pine or painted surfaces.
Check your boxes during the nesting season, removing broken eggs that have not hatched and dead nestlings. These will attract predators, ants and bacteria. Approaching the box will not permanently chase the parent birds away if it is done infrequently. Try to avoid checking the box a few days before the young fledge as it may cause them to leave the nest too early. It is not true that touching the nest or eggs will cause the parents to abandon the nest. The trail that you leave behind, however, may attract predators such raccoons, snakes, or mice to the nest. To safeguard your box from tree-climbing predators, place a two foot piece of aluminum flashing around the tree or post below the box.
During the nesting season, many people remove the nest materials from the box as soon as the baby birds have fledged. Although it is not necessary to do so in the southeastern US, removing the old nest may induce the birds to use it more than one time during the summer.
Thoroughly clean your box after the nesting season in October. Never use insecticides to clean your box. Mites can be controlled by using a pyrethrum based powder. Sevin dust is harmful to honey bees, so it should not be used. Often just whisking out the debris is enough. Since bird houses may become infested with wasps and hornets, you may want to remove the box from the tree and store it in a dry safe place throughout the winter months.
If House Sparrows or European Starlings begin to nest in the box, open the top and remove their nest materials so that other birds can nest.
CHALLENGES FOR CLASSROOMS
1. Have your class search for all the crevices, nooks and crannies around your school that would be suitable for wrens to nest.
2. Students can research the colors and numbers of eggs that make up each bird species’ clutch.
3. The terms incubation, clutch, brood, nestling, and fledgling are often used when discussing birds and their young. Spend some time in the library to discover the definition of each word.
4. Become a member of Cornell’s Nest Box Network. Check out their web site at http://birds.cornell.edu.
5. After removing the nests in the fall, have your class examine the materials used in the nest construction.
6. Most birds don’t use cavities in which to nest. Learn about other birds and their nesting habits.
7. Establish a Wildlife Habitat trail at your school. If you already have one, learn about the best sites for your bird boxes. Bat boxes and screech owl boxes can also be assembled for your trail.
More information can be obtained at the Georgia Wildlife Federation website at http://www.gwf.org.
8. Make more boxes for your school nature trail and woods. Have students decorate each box and acknowledge the most creative. (You may not want to place these boxes outside since they will not weather well.)
Birding Adventures, Inc.
Georgann Schmalz
Ornithologist
www.birdingadventuresinc.com