We humans exult in the springtime songs of the birds around us, appreciating the melodic way they fill our days with sound.

But for the creatures on the sending and receiving ends of these songs, they have a deeper meaning as precursors to a frenetic season of mating, nest building, egg laying and tending to offspring.

Of all the wondrous things birds accomplish, building structures to hold their youngsters is near the top of the list. Think about it for a minute: They lift and carry, push and pull, knot and weave, and pat and form building materials found out in nature to make nests just like their parents made. And they do it without ever having seen a nest under construction. This is an instinctive activity, something that’s hard-wired into their brains, providing them with an internal plan that produces the structure that works best for their species.

All Baltimore orioles weave and knot a distinctive hanging purse, goldfinches build a small cup around a forked branch and bluebirds use grasses and evergreen needles to construct a nest inside a cavity. Researchers studying wild birds in captivity confirm that they build the nest typical of their own species without ever having seen one.

This isn’t an entirely rote activity, though, because the available materials for constructing nests and the habitats for holding them vary widely, so their inner guide must be flexible. And as birds gain experience and become more skilled they continue to amend the basic plan: In raising their first brood, robins often learn to build under a branch or eave to provide rain protection, and orioles might select a thinner twig to hold their second nest, one that squirrels can’t scurry along to steal their eggs.

One complicating factor that all birds face is that they don’t want to catch the eye of a predator, such as a cat, hawk, raccoon or squirrel. So they seldom fly directly to their building site with mud, leaves, pine needles or grass stalks in their beaks. Instead, they exercise caution in their many trips to and from the nest site, approaching it from various directions and making stops along the way to confuse any watchful eyes.

Birds must be vigilant at all times to survive the challenges that life throws their way and this is especially true as they raise their young. It’s a gift to us that these wary creatures often choose to build their nests so close to us, sometimes right over a back door, under an eave or on an air conditioner, giving us a bird’s eye view.

 

St. Paul resident Val Cunningham, who volunteers with the St. Paul Audubon Society and writes about nature for local, regional and national newspapers and magazines, can be reached at valwrites@comcast.net.

Building sites

Cardinals choose dense shrubs, small trees or thickets to hold their nests.

Chickadees excavate holes in rotting trees or build inside nest boxes.

Blue jays use tree crotches or branches of evergreens or deciduous trees.

House wrens make their intricate twig nests inside tree cavities and nest boxes.

Rose-breasted grosbeaks choose forks in trees or shrubs for their cup nests.

Great horned owls commandeer old nests built by hawks, crows, eagles or squirrels.