To Create a Safe Place for Bluebirds, Start with the Correct Nest Box

  • Susan Champlin Taylor
  • Aug 01, 1998
For Steve Eno, it about rooting for the underdog. “These birds have had such a rough time,” says the soft-spoken Nebraska bluebird activist.

Once plentiful, the country’s three species of bluebirds--the eastern, mountain and western bluebird--have in recent decades lost many of their natural nesting sites to competition from nonnative birds, pesticide use and loss of habitat. “They’ve had the heck beat out of them,” says Eno, a board member of the North American Bluebird Society (NABS).

Eno is one of thousands of volunteers who have been trying--successfully--for 20 years to give the creatures a wing up with the use of man-made nesting boxes that provide safe havens for the birds. But any positive action can have a negative reaction: As sales of nesting boxes more than doubled from an estimated 100,000 sold in 1987 to nearly 250,000 in 1997, some manufacturers rushed to market with inferior products that in certain cases were nothing more than what Eno calls “death traps for bluebirds.”

Not long ago, NABS decided to provide manufacturers and distributors with recommendations for improvements they could make to commercial boxes. The group also sought ways to increase consumer education on the proper use and monitoring of the boxes.

“Essentially, we were looking for boxes that would keep the birds safe from predators, protect them from extremes of weather and be designed in a configuration that would be readily accepted by the bluebirds but not by nonnative species,” says Kevin Berner, a professor of wildlife technology at State University of New York, Cobleskill, and chairman of NABS’ Research Committee.

An appropriate box, he notes, should be made of sturdy wood to keep
predators out. It should also have a circular hole no larger than one and a half inches in diameter for eastern bluebirds, and one and nine-sixteenths of an inch for mountain and western bluebirds. The top should lift up for monitoring. “If the nest inside is made of fine grasses or pine needles and has a deep cup, then it probably belongs to a bluebird,” adds the scientist, who recommends removing nests only of nonnative species.

Bluebird experts assert that the boxes should be monitored weekly during nesting season to ensure that nonnative birds are not setting up house, to track population trends and to keep out parasites. “People call us and say, ‘This box isn’t working,’” says John Ivanko, co-executive director of NABS. “We ask them, ‘Are you monitoring it?’ And often they say, ‘Oh, we’re supposed to check on this?’ Or they’d let sparrows in and wonder why they didn’t have any bluebirds.”

Last January, NABS unveiled their new nest-box approval process, which includes a sticker and educational materials that retailers can distribute. To Eno and Berner’s surprise, the reaction from manufacturers was almost universally favorable. “It’s important for people to distinguish between boxes that are made to the proper specifications from those that are not,” says Jim Carpenter, president of the retailer Wild Birds Unlimited.

At the turn of the century, bluebirds were so prevalent in this country that ornithologist Frank Chapman wrote in 1904: “A bird so familiar as the bluebird needs no introduction.” Five decades later, sightings of the birds were few and far between. Their decline was due in part to habitat loss and also a misguided attempt to meddle with ecology. “There was a fellow who introduced 100 European starlings in New York’s Central Park about a century ago because he thought folks in the New World should enjoy all the birds Shakespeare wrote about,” says Berner. “Somewhere in his works (Henry IV, Part I), he mentions starlings. Now European starlings are one of the most abundant birds in North America.” Then there were the house sparrows, imported into this country to eradicate an insect pest. “But people ignored the fact that the sparrows have heavy seed-crushing bills, not insect-eating bills,” he adds.

The competition from these two aggressive birds pushed the more delicate bluebirds out of their natural-cavity nesting spaces. Bluebirds generally range in open areas, where they can easily see insects on the ground. The male selects the nest site and later the female lays an egg a day. But she does not incubate them until the entire clutch is laid (usually five eggs or so in the first clutch of the season; mountain bluebirds have slightly larger clutches).

People have been putting up bluebird nest boxes for decades. But not until the
mid-1970s did concerned birders begin an organized movement to give the birds safe places to nest. The activity took off. Soon thousands of enthusiasts were putting up boxes, leading to a resurgence in the birds’ numbers.

The U.S. Fish and Wildlife Service’s Breeding Bird Surveys, conducted since 1966, estimate that the population of eastern bluebirds (found east of the Rockies) has increased by 103 percent over the past 31 years. Though western bluebirds (found in the Southwest and on the West Coast) have not experienced a significant increase in their population, the number of mountain bluebirds (found in some western areas of the United States and Canada above 7,000 feet) has increased 98 percent over 31 years. “These are species for which people have directly caused their decline--and at the same time, they’re species for which individuals can do something to make a difference,” says Berner.

To bluebird lovers, anything that aids in bringing back these spectacularly colored, graceful and delicate birds is a cause for celebration. Steve Eno, who put out his first box six years ago and was immediately hooked, notes the deep gratification that goes along with creating a successful bluebird nest site: “Each sighting of a bluebird in a box,” he says, “is a little miracle. It’s exciting to know that it might not have happened if not for you.”

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