Along with sea otters, eastern bluebirds (Sialia sialis) rank among the doe-eyed poster children of the conservationist. Not only did we cause their decline, we can be helpful in their recovery! The fall out of this benefits many other less attractive species as well as the bluebird and the people involved.
There is something so thrilling about seeing that flash of blue wings and red/orange breast of the small male eastern bluebird. Their song is pretty and softly melodic. Their dependency on human help is both endearing and sad.
During the days of frontier settlement, vast areas of eastern US forests were cleared. This created the open spaces favored by bluebirds. Around the perimeter woods with live and dead trees, full of old woodpecker, decay and knot holes, were left standing. Fence posts were made of wood. Natural cavities were common and bluebirds thrived.
But the lovely eastern bluebirds are cavity nesters who can’t make their own holes. Over time snags (dead or dying standing trees) were less commonly left standing in situ. Wooden fences were replaced with metal posts. Pesticides took their toll. The bluebird population declined.
Non-native European starlings and the English house sparrows are more competitive that the gentle bluebird. Today the rare natural cavity is often filled by these more aggressive species. Bluebirds are left without a home. Those that do claim a cavity may be attacked by the more aggressive birds.
To fill the gap detailed instructions have evolved to build and maintain “bluebird trails”. Nesting boxes meet specifications that allow bluebirds to enter but screen out larger starlings. The aggressive sparrows are somewhat foiled by the lack of a perch post. Exotic interlopers are often killed by trained trail monitors. Native birds are protected by Federal laws and can’t be harmed to protect bluebirds. “Other native cavity-nesting birds, such as Carolina and black-capped chickadee, tree swallow, house wren, house finch, tufted titmouse, and great-crested flycatcher may use and are welcomed in nest boxes.” 1 Placement of the nesting box a good distance from human buildings and activity can reduce the appeal to birds like house wrens and house sparrows who strangely enough seem to prefer to nest near human activity. Placement of the nesting box in open fields a good distance from trees reduces the appeal to tree swallows. Pairing nesting boxes close together in one site helps to reduce use of both boxes by the territorial tree sparrows, effectively preserving one box of the pair for bluebird use.
Bluebirds are once again recovering.
A series of bluebird boxes is called a “trail” because bluebirds are territorial. At least 100 yards is needed between each nesting site if one hopes for at least one nesting box to be filled with happy bluebirds.
Other things that enhance the survival of the adorable eastern bluebird include open grassy spaces, shrubs and vines, widely scattered trees, places to perch outside of the nest box and food in the form of insects and berries. They meet their water needs with their daily food intake
One does hear stories of these little cuties reminding us that certain individuals have not read the manual. Bluebirds have been known to nest in all sorts of odd and “inappropriate” cavities.
(1) Gough, G.A., Sauer, J.R., Iliff, M. Patuxent Bird Identification Infocenter. 1998. Version 97.1. Patuxent Wildlife Research Center, Laurel, MD.
(image of "The Mad Bluebird" - a well known photograph by the Maryland artist, Michael L. Smith)
Beakless Bluebirds and Featherless Penguins: Observations of a Naturalist
by Sister Barbara Ann of All Saints Convent
published by Scriptorium Publications, Catonsville, MD
Bluebirds - Up Close
part of a video series by the National Audubon Society