Mark Thompson, Red Rock Lake Association
My first encounter with bluebirds was as a tyke when visiting my grandparents’ home. My grandmother had hung a well-outdated calendar picture of a bluebird on the wall. That photo was obviously one of her favorites since it was never removed or even replaced with a newer image. The photo, or most likely a painting, was that of a pair of bluebirds sitting on top of an old tin can nailed to a wooden fence post for a nesting structure. For years, I could only imagine what this vivid bluebird really looked like since I never saw one in the wild until later during my pre-teen years.
Bluebirds have long been considered harbingers of spring
and a symbol of happiness, love and hope.
In a nutshell, bluebirds are what the name indicates-blue. Henry David Thoreau wrote that, “The bluebird carries the sky on its back.” There are three species of bluebirds found in North America: eastern (Sialia sialis), mountain (S. currucoides), and western (S. Mexicana). Species can be identified by slight differences in their plumage. As a group, they are medium-sized. Males are predominantly blue with rufous to light blue breasts. In all three species, both sexes have similar color patterns and there are no noticeable differences in size, though females are less brightly colored than males.
The eastern bluebird’s range extends east of the Rocky Mountains from southern Canada south to Nicaragua. Easterns are known to interbreed with mountain bluebirds where their ranges overlap. The farther north an individual’s breeding range is, the farther they need to migrate south to find available food and to escape cold winters. Breeding ranges in western Manitoba may require migrations of up to 2,000 miles south to the southeastern United States or Mexico. Bluebirds from the southeastern U.S. may only travel a short distance or remain on their breeding territories year around.
When our country was settled from east to west, bluebird populations were no doubt abundant, and probably as common as the American robin. In fact, numbers flourished as virgin forests were cleared which provided even better habitat for the bluebird. Being secondary cavity nesters, those that seek out pre-existing cavities to nest in, bluebirds historically nested in hollow trees, wood fence posts, and eventually nooks in building structures.
In the mid to late 1800s, ships carrying additional immigrants from Europe also gave passage to two feathered immigrants, the starling and European house sparrow. Both of these birds easily adapted to rural farmland, and because they both liked roofs over their heads, the aggressive squatters soon took over the more-gentle bluebird’s nests. The conversion of woodlands to agricultural lands, the culling of dead trees, and the replacement of wood fence posts with steel posts only further declined populations.
In the late-1800s, birding enthusiasts and conservationists monitoring population declines devised plans to reverse population losses by creating housing or nesting structures to replace the loss of historic nesting sites. Soon, artificial nesting structures, though primitive, such as the old tin can used on the calendar on my grandmother’s wall, were placed and readily accepted.
Today, “bluebird trails” and other nest box promotions provide additional nesting sites to reduce competition. Houses properly designed and strategically placed, along with proper monitoring to prevent invasive species from inhabiting them, have resulted in one more success story for conservationists and nature watchers. According to the North American Breeding Bird survey, populations have increased almost two percent per year between 1966 and 2012. Partners in Flight estimates the global breeding population at 22,000, not what it was during our country’s settlement, but way better than that of the early twentieth century.
The best habitat to observe Bluebirds is open or semi-open grasslands around trees with an open canopy, and with sparse ground cover, and little understory. Areas favorable for optimal usage include along pastures and shorter grasslands, suburban parks, golf courses, agricultural fields, cemeteries, and backyards. Perching sites including fences, medium sized trees, and utility lines provide perches for hunting and nest guarding.
Numbers of bluebirds have nested in the houses we have provided. Still, we are captivated when we catch a glimpse of blue flitting from tree to tree and stop what we are doing to soak up the excitement.
Local links; nest structure plans and more Bluebird information.
Iowa Ornithologists Union - Bluebird Trails: Getting Started with Bluebirds
Build a Birdhouse: Natural Resources Conservation Service
Also a highly recommended book with birdhouse plans for numerous birds and habitats:
Woodworking for Wildlife: Homes for Birds and Animals By Carrol L. Henderson - Nongame Wildlife Program, Minnesota Department of Natural Resources