One of the most fascinating experiments I've ever read about, concerned the release of weaver finches—birds of the tropics which had been kept in captivity through three or four generations—back into the wild. During those years, the birds had no access to any kind of nesting materials, yet when their offspring were released, they reportedly began building nests in the same way their ancestors did four generations earlier!

     Even though most birds do not have to be taught, almost all species are skillful nest builders. Each species builds basically the same kind of nest as their kind before them. Some build nests of a specific design and use the same basic materials. They also tend to build in the same types of places. Some build on the ground others high in the trees and others at various heights in between.

     Some nests are small, just enough to accommodate the bird. Some are expandable to grow with the brood. Others can get very large, often weighing hundreds of pounds. Nests of songbirds (passerines) are mostly pocket-like. Some are basket-like. Other birds build platform-like nests and still others build floating nests. Birds are skillful weavers, masons, potters, carpenters, and diggers. Their abilities are mind-boggling and their persistence is inspiring. Some utilize existing cavities or form their own. Others use holes in a dirt bank or dig their own. Some merely use a scrape or depression in the sand or dirt. To cliff-nesters, manmade skyscrapers become substitute cliffs; bridges become caves. Houses, barns, and outbuildings provide nooks and crannies to nest in. Manmade birdhouses, and nesting boxes and platforms, provide suitable substitute sites for cavity nesters.

     Robins are probably the most common nester in our yards, nesting in cities, suburbia, parks and farms. They begin with a base of large plant stems and leaves, then begin adding finer grasses, string and the like, cleverly mixing it with mud that the bird picks up from puddles or other wet places. The hen plasters the mud on the inside of the nest then carefully shapes it from the inside by turning around, molding it with her breast and belly. Finer grasses, rootlets and animal hair is then woven into and over the mud walls. 

     Watching a robin, or any bird build a nest is a good lesson in the trait of persistence. Starting from nothing, the seven or eight inch bird will make hundreds of trips, working unceasingly to complete its task. If only we could learn such patient persistence in all we do. And the bird never waivers. It seems to us as if the job is going to last forever, yet within a few days her nest is ready. Sometimes its not even that simple. In some instances, rains or high winds destroy all her effort. But, she doesn't quit. She'll begin all over again, working until she has a completed nest in which to lay her eggs.

     There was an instance, some years ago, of a robin building a nest on a railroad turntable. As I remember, these turntables were for redirecting the big steam engines onto tracks heading in different directions. The engine and coal car were driven onto the turntable and it was turned to match it up with the track heading in the proper direction. The robin had chosen a specific location on one of the many tracks, which were like the spokes on a wheel. She had almost completed the job when the position of the turntable was changed. She came back to the spot, but her nest was gone. Of course it wasn't, it had just been rotated to a different position, and the bird apparently did not have the inclination to look for or use it. She had designs on that specific location, so she began constructing another nest, all this amidst the noisy activity of the each day. Of course, the turntable continued to revolve to different positions frequently as engines were directed to different points east, west, north south and in-between. Each time she was interrupted, she began building a new nest in that specific favored location. That little robin ultimately built or partially built no less than nine different nests! Oh that I would have such persistence!

     Robins aren't the only birds to be skilled in masonry or pottery. Barn swallows and cliff swallows also use mud. Barn swallows nest on beams or any place a protected flat surface is created. The inside of barns, under bridges or wharves are all popular places for the barn swallow to build. They mix straw or grass with mouthfuls of mud to form their open-topped nests lined with feathers. You'll often see them gathered around muddy-edged puddles in spring, collecting mud. Cliff swallows form gourd-shaped mud structures under cliff ledges, large bridges or tall buildings, and even in large cave-like culverts. They are gregarious and build in colonies. Cliff swallows actually form mud pellets which are cemented together with saliva, from special salivary glands that also serve to waterproof the structure. These "adobe villas" are lined with fine grasses and feathers.

     Another family of birds that shows some interesting and unusual nesting habits are the wrens. They are known by the scientific name troglodytidae, which means "cave-dweller". Of course, wrens do not live in caves, but some of them tend to seek out cave-like crevices or build a nest that is cave-like or covered. The marsh wren builds a globular or ball-shaped nest using strands of cattail leaves, rushes or marsh grasses along with cattail down, then lines it with fine grasses and feathers.

House wrens will nest in tree cavities or crevices, as well as readily using manmade housing. The Carolina wren and sometimes the house wren, are the little birds that choose some unusual nesting locations. They will nest in clothespin bags, old hats, coffee cans, cooking grills, carpenter's belts left idle too long, the foot brackets of water skis and on light fixtures out the back door.

     One man in Hanover County, Virginia noticed a small brown bird that seemed to always be around the front windshield of his car each morning as he left for work. At first, he didn't pay much attention to it, but then noticed the same bird, waiting close by each evening when he returned. After a couple of days went by, he realized one morning that the bird was coming up out of his windshield wiper well when he started the car. Upon investigation, he found the nest with four tiny eggs in it. The ride to work was 10-12 miles to and from each day. Apparently, the engine heat was enough to keep the eggs alive and viable until returning home to the parent bird each day. He parked his vehicle for about 10 days or so, and hitched a ride with a neighbor, allowing the four eggs to be hatched and the resultant young reared successfully.

     Other birds that we might find nesting around our home are brown thrashers, catbirds and mockingbirds, all of which build similar nests of twigs and coarse grasses. They line them with rootlets that actually help to maintain the pocket shape as they dry out. Mourning doves build a simple platform with only a slight depression, using mostly twigs. Cardinals build a nest similar to robins but with more woody material and no mud. Orioles build higher up in the trees, weaving a basket-like nest of dried vegetable fibers, string or yarn, rootlets and animal hair.

     The eastern phoebe builds under overhanging rocks, upturned root systems of large trees, under small bridges, sheds and little ledges on the house, especially the ceilings of porches. It also uses mud and grass, lining it with rootlets and feathers, and covering the outside with moss. The little chipping sparrow builds a pocket-like nest of fine grasses, rootlets, and animal hair, usually in low-growing pines or shrubs.

     The variety of types, materials and locations are fascinating. Watch your backyard this spring. You'll be surprised who is living with you. You won't get much rent out of them, but they will keep the bugs down and make life a little more enjoyable and interesting. 

© 2002 Spike Knuth All Rights Reserved
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