For most birds spring is the season of nesting, and several of our local songbirds don’t mind making themselves at home in our homes.
“We have a large deck with some shelving in one protected corner,” writes Anke Riccio of Ridgefield. “Just days after moving in, a Carolina Wren couple moved in with us! They built a nest right on the shelf and delighted us for weeks with their building, singing, incubating their eggs and finally seeing the little ones take off.
“So last spring we put an old shoebox (with a hole cut into it) in that spot ‘to make it cozier’ for them — they moved right in! Despite our dog and small child, they had a successful nesting time and their babies left the nest one evening while we were sitting outside having dinner! It was very exciting!
“We brushed the box clean in the fall, brought it inside for the winter and put it back in place in early spring. The Carolina Wrens came back and started building.
“Here is my question: For several days we saw them both building constantly, then all of a sudden we didn’t see them anymore. A couple of days later I saw one of them again flying to the nest with building material in its beak and then nothing again. For the last week or so there was no activity. We can hear them singing on the property (we have an open space area right next to us) but they have not been back to their nest. Is it something we did? Can you explain that?
“I am worried about ‘our’ couple and would love to understand their behavior better.”
A few days later, Anke wrote that the wrens have reappeared at the box and seem to be back at work.
It is possible that that something in the environment — the sighting of a cat or even a snake on the hunt nearby, for instance — will dissuade wrens from continuing a nest. However, wrens commonly build “dummy” nests.
While it may seem a waste of time and energy to build two, three or four nests when only one is needed, various species do so, and for various reasons.
Some birds use nests as part of the mating ritual. Each spring when it establishes its territory, the male House Wren builds several incomplete nest structures, made of twigs. These may be in cavities or sheltered places.
When a female shows up, the homebuilder begins wooing her by singing and hopping in and out of each nest — almost like an overly enthusiastic real estate agent showing off different homes. When the female picks one, she often tosses out the work of the male and builds her own nest. Sometimes, she finishes off the male’s work by lining it with soft grasses.
The leftover stick structures may serve to define the territory of House Wren, discouraging other birds from using the locations for their own nests.
Other species may build multiple nests to throw off predators. The more structures that look like nests that appear in an area, the less unusual the real nest looks in the eye of a potential enemy.
Many human contractors build groups of houses together in order to save time and money on materials, equipment and labor. Some birds, such as the Prairie Warbler, may engage in the same kind of construction efficiencies. They build several nests at one time because they are in nest-building mode. Extra nests may be used for second or third broods after the first brood is raised.
At any rate, it’s quite possible that the Carolina Wrens, which also practice multiple-nest building, have been working at several nests at once. That may explain their disappearance for periods of time.
Incidentally, Carolina Wrens are very adaptive in finding nest sites around humans.
Arthur Cleveland Bent, who wrote a wonderful series of life histories of our birds that was published by The Smithsonian Institution, reported on the Carolina Wren: “Nests of the more domestically inclined wrens have been reported in a great variety of nooks and crannies in, about, or under buildings of various kinds, under bridges, or in holes in fence posts. Almost any kind of receptacles left lying around, such as tin cans, coffee pots, pails, small baskets, pitchers, or empty boxes may be used. Old discarded hats and caps or the pockets of old clothes, coats, or overalls, left hanging in sheds or on porches, may offer acceptable nesting sites. Nests have been found in mail boxes, bird boxes, old hornets’ nests, and ivy vines growing over porches; and the nest is sometimes built in an unused cupboard or on a mantel shelf inside a house.”
He cites a Dr. Witmer Stone who reported in 1911: “In a country place near Philadelphia, a pair of Carolina Wrens entered the sitting-room through a window that was left partly open, and built their nest in the back of an upholstered sofa, entering where a hole had been torn in the back. Needless to say, they were not disturbed, and given full possession until the young were safely reared.”
Birding Classes: Birds in their Habitats, Saturday, May 26, 9:30 to noon, $15/adult — kids free, Audubon Greenwich parking area at 613 Riversville Road, 203-869-5272 x230, greenwich.audubon.org
Copyright 2012 by Jack Sanders. Send sightings or comments to: jackfsanders [at sign] gmail.com, or to Bird Notes, Box 1019, Ridgefield, CT 06877. If you need help identifying a bird, try your local nature center. If you find an injured bird, call wildlife rehabilitator Darlene Wimbrow of Redding, 203-438-0618, Wildlife in Crisis of Weston, 203-544-9913, or Wild Wings of Greenwich, 203-637-9822. The columnist’s website is www. sandersbooks. com.