AN ARCHITECTURALLY INTRICATE NEST: A wee House Wren goes “au natural,” nesting in a street tree cavity. Photo by Keith Michael.

By Keith Michael

This little wren went to market,

This little wren stayed home,

This little wren had, well, caterpillars,

This little wren had none.

And this little wren went, “Wee wee wee” 

all the way back to the nest.


Let’s face it: Birds are baffling. They have feathers. They can fly. They either migrate incomprehensibly long distances or survive brutally cold northern winters, without long johns or down coats. (Oh wait, they do have down coats, but still, those twig legs!) Their eyes are on the sides of their heads. They hatch from hard eggs. (“Which came first…?” is the ultimate riddle.) And they build architecturally intricate nests.
On the sidewalk, a bright blue Robin’s egg catches my eye (and Millie’s nose). At the end of her leash, Millie’s corgi-shortness is the perfect vantage point for examining this seemingly alien shell tottering in the summer breeze. I have to stoop to pick it up while looking for the other half at the curb. Perfectly smooth, a bit of down feather stuck to the outside, and that color! Look up. Where’s the nest? The branches of the willow oak above are too dense to find it. But that’s the point: Hidden is better.
The basic purpose of a bird’s nest is similar across species: to build a protected place to lay eggs and care for the hatchlings. Incredibly, the strategies and range of engineering skills employed for this safe place run the gamut from the nearly non-existent to the equivalent of raising a fortress with sentries.
Our common red-breasted American Robin constructs what most of us think of as the classic bird nest: a comfortably robin-sized bowl woven of twigs and grass secured in the fork of a tree branch. The eggs are laid, obviously, in the center. Simple. But how do Robins know how to construct this perfectly efficient nursery the first time, every time? There are no pre-assembled starter models, no ‘How-To’ manuals to Google, no Ikea instructions that come with all of the pieces in the box (one hopes) and the note: “Some assembly required.”
Aside from this classic nest, the variants of style and ingenuity are nearly endless. Hummingbirds make a Lilliputian demitasse cup from spiderweb silk and lichen flakes. Woodpeckers, rather than weathering the elements of the great outdoors, prefer the arduous task of chiseling a hole in the trunk of a tree, creating a tidy round woodpeckers-only doorway that keeps unwanted company out. The fiery orange and black Baltimore Oriole has the opposite strategy. They’ve moved out to the suburbs at the very ends of tree branches to weave a hanging silken pouch for their eggs, choosing wind-blown leafy twigs so tiny that even squirrels can’t trapeze to them. Then there are the Barn Swallows and the Chimney Swifts who build elaborate mud nests under eaves or bridges (Swallows) or inside chimneys (Swifts), one mouthful of mud at a time.
Birds known as cavity-nesters—Sparrows, Starlings, Bluebirds, Kestrals, and our wee-wee-wee-ing House Wren—prefer setting up housekeeping in a pre-fab home. Being near people, our buildings suit them just fine. We provide a bounty of nooks and crannies protected from the rain and isolated from homewrecking predators. Check out the Starlings gallivanting in and out of window pediments or roof cornices, and the House Sparrow co-ops at every intersection in the T-bar pipe supports for the traffic lights. Bluebirds and Kestrals have readily adapted to man-made nest boxes, though they’re very finicky about floor plans, ceiling heights, and accessible entrances.
Larger birds such as hawks and herons demand more real estate. Their piles of ever-larger sticks are more likely to be retrofitted year after year, whereas smaller birds painstakingly start from scratch each season. An eagle’s nest can grow to nearly a ton and can be reused for decades. On the ephemeral end of the spectrum, gulls, terns, and shorebirds that “nest” along the coast, travel light, barely scratching an indentation in the sand before depositing their tidy clutch of eggs, maybe pushing a few pebbles nearby as egg-like camouflage. Beach-nesting birds, oddly enough, don’t sit on their eggs so much to keep them warm, but to shade them so that they don’t hard boil in the sun!
As for the ‘nest-as-fortress’ model, visit Green-Wood Cemetery in Brooklyn and look up at the imposing gothic gateway entrance. At the top of the central spire is a mammoth installation of sticks. Screaming to and fro are dozens of green, blue, and white Monk Parakeets (their provenance from Argentina is another story). This pile of sticks is a fly-up condominium with multiple entrances. Any predator should think twice (or even once) before raising the wrath of this boisterous coven of sharp-tongued (and billed) birds.
Millie has stood, or rather sat, in the hot sun quite long enough, and her eyebrows inquire, “That egg shell is very nice, but can’t we go back to our air-conditioned nest now?” I acquiesce.

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