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Wildlife Wonders

Today is Eastern Bluebird Day!

Somewhere over the rainbow

Bluebirds fly.

Birds fly over the rainbow –

Why then, oh why can’t I?

Edgar Y. Harburg, From “Over the Rainbow”, Wizard of Oz

As Henry David Thoreau wrote “The bluebird carries the sky on his back.”  This aptly describes the male bluebird (Sialia sialis) so beautiful as it is seen flying across a meadow.  The blue is really like no other, so rich and jewel-like.  The male has the dark blue on its head, back, wings and tail.  Like the American Robin, its cousin in the thrush family, it has a rusty red breast and its belly is white.  The adult female is similar, but a more muted color, light gray tinged with blue on its head, tail and wings.  Its breast and flanks are light reddish brown and the belly is white. Both male and female adults are about 7” in length. The juvenile is similar to a female, but with spots on its chest. 

Why are these birds so remarkable?  Well one reason is that their return is another wonderful conservation success story brought about because of human intervention.  Yes, it is true because of human actions the numbers did decrease.  It appears that a couple of things happened – the introduction of the house sparrow in 1851 in Brooklyn, New York and the starling in 1890 from Europe, and the reduction of farmlands, ideal bluebird habitat, as well as the removal of standing dead trees for firewood.  (The European starling was first brought to North America by Shakespeare enthusiasts who wanted America to have all the birds that Shakespeare mentioned. 100 birds were set loose in New Yorks’ Central Park.)  The house sparrow and starling, both cavity nesters, out competed the bluebirds for nesting areas. 

Records indicate a marked decline of the eastern bluebird from 1938 – 1970s. In addition to habitat loss and pesticide use, severe ice storms that covered berries, bluebirds main winter food, caused devastating effects. Bluebird nest boxes began to be built in the 1970s and bluebird trails were established.  Undoubtedly this helped stop the decline and today bluebirds are found statewide. Partners in Flight, a cooperative effort that focuses on the conservation of land bird species, estimates a “global breeding population of 20 million, with 86% spending at least part of the year in the U.S.”.

The eastern bluebird is the only bluebird found in New England, the other bluebirds found in North America are the mountain and western bluebird.  The eastern bluebird range extends to Nicaragua.  Bluebirds prefer open habitats – farmlands, orchards, meadows, parks, cemetaries, and golf courses.  Here they perch on wires and fence posts overlooking fields for insects.  Bluebirds are skilled fliers with incredible vision.  They can spot an insect from 60 feet away. Their major food includes crickets, grasshoppers, beetles, caterpillars, and spiders.  In fall and winter they consume a large amount of berries. 

Bluebirds use natural cavities that were made by woodpeckers for their nests and human-made nest boxes.  Males are territorial and will attack other species they deem a threat, no matter if they are cavity nesters or not.  Males will attract a female to a nest site by carrying material in and out of a nest hole, perching and fluttering his wings.  They remain a bonded pair for several seasons. She makes a neat nest of grasses and pine needles sometimes lined with horse hair, turkey feathers or deer fur.  The female then lays 2-7 pale blue eggs and incubates them for 11-19 days.  When they hatch they have no feathers except a few traces of down and their eyes are closed.  By day 5 the feathers develop.  Young remain in the nest for 17-21 days.  Both parents bring food to the nestlings.  Bluebirds will use the same nest for multiple broods during the season.  They normally produce two broods annually, but will have three if the weather conditions are favorable and the food supply is sufficient. Sometimes individuals from the first brood have been observed remaining with the parents and helping to feed a second brood.  

In late summer the parents and young from various broods form a small flock and stay together as they feed.  In fall the family joins with other families, to form flocks of  5-20 to as large as 100 birds. In northern areas they start migrating in October and November. Banded eastern bluebirds from New York and Pennsylvania have been found in Florida; birds from Massachusetts and New Hampshire have been found in Georgia and the Carolinas.  If food is abundant bluebirds might remain in their breeding area.  In Connecticut, bluebirds are becoming more common year-round.  

Bluebird boxes are often monitored to record the progress of nestlings and to control house sparrows.  Bluebirds are sometimes infected by the parasitic blowfly that sucks the blood from nestlings.  Normally if there are no other stress factors no action needs to be taken.  If there is prolonged rain or drought, or food shortages control measures may be necessary. 

DEEP Wildlife Division’s “Connecticut Bluebird Project” had distributed rough-cut lumber to organized groups – schools, scouts, conservation commissions, and garden clubs since 1980.  For 40 years, in Connecticut, thousands of people have been involved in helping the bluebirds by constructing, installing and maintaining bluebird nest boxes.  

Bluebird nest box plans are available through DEEP (See Resources).  Since there are many nest box designs it might be helpful to review this checklist for a successful bluebird box:

  1. No perch – this may encourage house sparrows.
  2. Entrance holds should be 1 ½” – 1 ¾” in diameter.
  3. Predator guards should be placed around the entrance hole to prevent starlings from enlarging the entrances.
  4. Floor dimensions should be approximately 4 x 4 inches.
  5. From the floor to the bottom of the entrance hole it should be 5 – 7 inches.
  6. Opening the box should be easy for both monitoring and cleaning.
  7. Drainage holes, either holes drilled in the floor or gaps between floor and sides
  8. At least ¾” thick wood should be used for building material.
  9. Ventilation – by drilling holes at the back or sides or gaps between roof and sides
  10. Roof should overhang the entrance hole by 1-2”
  11. Keep boxes at least 100 yards apart.
  12. Select good habitat and avoid brushy and heavily wooded areas.

A bluebird is perceived as a symbol of joy and happiness. The “bluebird of happiness” can become part of your life. You can attract bluebirds by building nesting boxes and/or planting native trees, shrubs or vines that provide fall and winter food for bluebirds.  Some favorites include dogwoods (trees and shrubs), mountain ash, smooth or staghorn sumac and Virginia creeper.  Hopefully you will get to hear the soft, melodious tu-a-wee of the eastern bluebird or see the brilliant flash of royal blue as the bluebird flies across the field.  


Wildlife Fact Sheet – Eastern Bluebird

The Bluebird Book – The Complete Guide to Attracting Bluebirds by Donald and Lillian Stokes

All About Birds:  Eastern Bluebird

Eastern Bluebird Overview, All About Birds, Cornell Lab of Ornithology

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