Wild Ideas: The precarious existence of bluebirds

A male Eastern Bluebird scores some insect larva.Bruce Jones
A male Eastern Bluebird scores some insect larva.

Somewhere over the rainbow
Bluebirds fly.
Birds fly over the rainbow.
Why then, oh why can’t I?

– Harold Arlen, “Somewhere Over the Rainbow”

My landlord put up two bluebird nesting boxes this winter, one in his yard and one in mine, attaching the latter to one of the wooden posts holding up my clothesline. It was a nice idea, but unfortunately, what it was mounted to and its location on the edge of the forest made the box vulnerable to predators, such as raccoons and snakes.

Although bluebirds will nest in tree cavities up to 50 feet off the ground, they prefer to be closer to the insect prey they hunt for on the ground. Their propensity for picking such low nesting sites enables easy predator access. As secondary cavity nesters, bluebirds usually compete with other species for vacant holes created by woodpeckers.

Fortunately, specifications for constructing and mounting secure nesting boxes are easy to come by from various bluebird organizations, including the Virginia Bluebird Society. At my suggestion, my landlord checked out the specs on the VBS website and made adjustments to the box in my yard: He moved it to the top of a metal pole he’d put in the ground and added a conical metal guard under the box. He also put a hinge on one side of the box so the box could be accessed to clear out the nests between broods. Finally, he added a wire mesh guard extending out from the entrance to prevent predators from reaching into the box.

The pair of Eastern Bluebirds that have taken up residence in a special nesting box designed for them, in the author’s yard. The male is on the top of the box, and the female is in front of its entrance hole.Pam Owen | Rappahannock News
The pair of Eastern Bluebirds that have taken up residence in a special nesting box designed for them, in the author’s yard. The male is on the top of the box, and the female is in front of its entrance hole.

Why do we go to such lengths to provide safe housing for bluebirds, when plenty of other bird species might need our help? Of course, bluebirds are beautiful, especially the male, who is deep blue on top and, like the American Robin (another native thrush), has a rust-colored breast. Perhaps because of their beauty, bluebirds have had a positive place in mythology and other aspects of human culture going back thousands of years.

However, bluebirds are also special in another way – their vulnerability to extinction. Beyond loss of habitat from human activity, which is taking such a huge toll on many native species, bluebirds have had a complex relationship to Homo sapiens. Revered by many Native American tribes, the bluebird’s history changed dramatically when the European colonists arrived. What started out as a benefit to the birds became a huge cost over time.

The Eastern Bluebird (Sialia sialis), the only one native to Virginia, particularly benefited early on from the colonists’ clearing land and building wooden fences for farming. They also planted orchards of low-growing fruit trees that, as they aged, offered lots of dead limbs suitable for turning into nesting cavities and open areas for foraging.

The downside of the European invasion came in the 19th century, when Starlings and House Sparrows were purposely introduced into the country. Actually European Weaver Finches, House Sparrows will kill adult bluebirds as well as their young before taking over a nesting box, and both species are among bluebirds’ biggest competitors. European settlers had also brought with them what has become one of the leading threats to the survival of all songbirds: the domestic cat.

If these threats weren’t enough, eventual modernization of farming led to metal fencing’s replacing wood, and orchardists’ becoming more ruthless about pruning orchard trees of their dead limbs. With the shift to industrialization and growth in the human population, more and more farmland was converted into residential and industrial developments, leading to more habitat loss for bluebirds. The advent of chemical pesticides in the middle of the 20th century was the proverbial straw that almost broke the species’ back.

As bluebird expert Lawrence Zeleny wrote in a June 1977 National Geographic article about the preceding 40 years, “the population of the eastern bluebird may have plummeted by as much as 90 percent.” The species had become, according to Zeleny, “so scarce that most people under 30 have never seen one,” with extinction “a real possibility.”

Zeleny’s writings about how to help save bluebirds brought their plight to public attention. He founded the North American Bluebird Society, and similar organizations started forming across the country, including the Virginia Bluebird Society. Some of these organizations have encouraged landowners to set up nesting-box “trails,” with landowners or other volunteers monitoring the boxes for the health of bluebird broods, ousting any nonnative invaders from the boxes and clearing out the nest after each brood has left to avoid infestation by parasites.

Through such efforts, bluebirds are making a comeback. These days most of us living in the Blue Ridge are fortunate to see them regularly, especially if we provide nesting boxes that are up to spec.

Although the pair of bluebirds that had overwintered on the property where I live seemed to have claimed the nesting box in my yard not long after it was relocated on the metal pole, they ended up moving down to the one in my landlords’ yard for some reason. Unfortunately for my landlords and the birds, but fortunately for me, a bear came one night just after the pair had settled in, bent the mounting pole to the ground and absconded with the box. Now the pair has settled back into the box in my yard, and the female appears to be brooding.

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Pam Owen
About Pam Owen 280 Articles
Writer, editor, photographer, and passionate nature conservationist living in Rappahannock County, in the Blue Ridge Mountains of Virginia. Two favorite quotes: By E.O. Wilson, who coined the term "biodiversity," "Nature holds the key to our aesthetic, intellectual, cognitive and even spiritual satisfaction”; by Douglas Adams, “I love deadlines. I love the whooshing sound they make as they pass by.”