Many years ago I had the wonderful experience of teaching second graders in an Audubon after-school program in Washington, D.C.  Our most memorable activity, for me, was our attempt to create bird’s nests.  Was it ever hard!  The human hand, though incredibly dextrous, turned out to be no match for a bird’s beak and feet!  The nests we made looked pathetic, compared to the intricate structures birds routinely make. 

     I was reminded of this experience when I read an excellent article in appreciation of birds’ nests.  I include here excerpts from that article, “Small Miracles” by Kenn Kaufman (AUDUBON, March-April 2008) along with links to some awesome photos that were published in the magazine.–April Moore

http://audubonmagazine.org/features0803/14songSparrow.html

http://audubonmagazine.org/features0803/2hoaryRedpoll.html

http://audubonmagazine.org/features0803/15westernTanager.html

http://audubonmagazine.org/features0803/7tennesseeWarbler.html

http://audubonmagazine.org/features0803/8smallGroundFinch.html

“Impatient for winter to be over, we had put on our boots to go seeking signs of spring but had instead found a sign of the previous summer.  We must have walked past this thicket a score of times last summer without ever noticing birds around it, but here is a bird’s nest among the branches, at eye level, in plain sight now that winter has stripped away the last of the leaves.

“It would be easy enough to pass it by.  If we pause to look closely, though, it becomes more intriguing.  We may never know what kind of bird built the nest, because there are several species here that might construct this type: an open-cup shape lashed into a three-way fork in an upright twig.  But it inspires a sense of wonder beyond mere questions about identification.  Somehow a small bird knew how to gather the myriad material for this structure.  Somehow this bird arranged scores of small pieces of twig and grass and weed and bark, weaving them together with such precision that the nest is still sturdy and secure after being exposed to the winter’s rain and wind.  Considered in the proper light, this little bundle of dried vegetation is really a small miracle. . . . . .

“Birds do not live in their nests the way humans live in their houses.  A few species, such as some wrens, will use them as shelters to sleep in at night, but they are the exceptions.  For the majority, the nest is just a cradle.  Built to hold the eggs and the helpless young, it is abandoned once the young birds are old enough to leave.  In most cases it is never used again. . . .

“. . . .for variety of placement and material, and for sheer complexity of design, nothing can compare with birds’ nests.  Especially among smaller birds, nests are often remarkable for the inventive use of local materials to provide support, shelter, and camouflage.  The nests are tiny marvels of disposable architecture.

“The skill to create them comes almost entirely from instinct (althought there is evidence that young adult birds, making their first nests, do improve with practice).  Studies have shown that at least some birds, hand-raised in captivity, can build a nest typical of their own species without ever having seen one.  The instinct to do this must be flexible, because the locations and materials available for nests in the wild vary, but it must be based on a considerable amount of precision as well.

“Even a small bird’s relatively simple nest may be composed of several kinds of material used for different purposes.  For example, a white-crowned sparrow’s may have coarse twigs at the base, finer twigs and weeds intertwined with rootlets and bark strips to form the open cup, dry leaves in the outer edge, and fine grasses and other soft materials molded into an inner lining.  And that’s just a simple number.  A more complex nest, such as the long hanging pouch of an American oriole, may involve actual weaving or sophisticated knots tied in long plant fibers, and it may take days of intense effort to build.

“Most birds are opportunistic when it comes to building materials, and will readily incorporate manmade items into their nests if they fit basic requiremens of size and texture.  Paper, string, nails, pieces of wire, and bits of fabric regularly show up in the handiwork of suburban birds.  In some areas house finches have become a minor nuisance by dismantling nylon window screens to use the strands for their nests.

“In many cases, though, the materials chosen must have specific properties.  Studies of nesting European starlings have found that the birds were selecting certain plants, such as wild carrot and yarrow, containing chemicals that would inhibit the growth of mites and other parasites.  In eastern North America the great crested flycatcher often adds a piece of shed snakeskin, and the power of suggestion imparted may help deter predators or other intruders.  Chipping sparrows often use animal hair (gathered in farmyards, or even plucked from startled pets) for their nest lining.  Feathers are also ideal for soft, insulating lining material.  Big birds like quail or ducks use their own down feathers for this purpose, but swallows and other small birds prefer feathers dropped by larger birrds.  A truly extreme example of material gathering is practiced by certain tropical swifts, fast-flying small birds that will actually strike much larger birds in midair to knock feathers loose.

“As a very general rule, females are the skilled builders.  For many species they do all the construction, including some (such as hummingbirds) for which males abdicate any responsibility for helping with the nest or young.  In other cases, the male provides the basic foundation and the female adds the detailed lining.  A male marsh wren may build 20 or more ’dummy nests’ around his territory;  the female chooses one, adds lining, and uses it as the actual site for the eggs.  The male’s building spree is not wasted effort:  the presence of all those decoys may provide some protection for the real one, as predators tire of raiding nests that turn out to be empty.

“Some of the most impressive nests are also among the smallest.  A hummingbird nest is a wondrous creation of tiny plant fibers, mosses, and spiderwebs, so small that a 50-cent piece would completely cover it.  It is as soft as felt but strong, with the spiderwebs making it pliable enough to stretch and expand as the rambunctious young hummers grow and exercise in it.  Many hummingbirds will camouflage the outside with bits of lichen.  At a distance such an object looks, for all the world, like a natural bump or knob on the branch, thereby deceiving potential predators in the mother bird’s absence.

“At the opposite extreme are eagles.  A pair of bald eagles may use the same nest for years, adding material to it annually until it becomes huge (an extreme example can reach a depth of 20 feet and a weight exceeding two tons).  Such a nest is merely a ramshackle heap of sticks, hardly an admirable piece of avian architecture, but it does have its admirers:  house sparrows and other small birds sometimes tuck their own nests into the lower crevices, and great horned owls may commandeer the entire nest, perhaps even driving the eagles from their aerie.

“The finest nests are crafted by smaller birds, however, and the majority re never reused, not even by their original builders.  It seems all the more remakrable that birds should create these intricate structures for such ephermeral use.”

        

 

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