Bylane Bluebirds
By Sean Prockter
  This summer (2004) I was recruited by Bedford
Audubon Society to monitor their 10 Eastern Bluebird nestboxes at Bylane Farm in
Katonah, New York. The Eastern Bluebird, Sialia sialis, is a species of thrush that
requires nesting cavities in dead or dying trees. A nestbox, in lieu of a dead
tree, provides an ideal situation for bluebirds that they readily accept near
open fields. Approximately seven inches in length, the bluebird is a handsome
bird, with a blue back and head and a contrasting, rust-colored breast. They
have a cheerful, warble-like song.
The results of my monitoring project found that
of the ten nestboxes at Bylane, eight were occupied by Eastern Bluebirds. These
eight pairs produced 67 eggs which eventually fledged 52 young bluebirds. The
eight pairs nested a total of 12 times as one pair can nest up to three times in
a single nesting season from May to early August. Typically bluebirds will lay 4
to 5 eggs per nesting. Tree swallows also nested in some of the boxes and
successfully fledged eight young.
The biggest threat to the success of bluebirds is
the presence of the European House Sparrow, a non-native, invasive, and
aggressive bird. The House Sparrow is commonly associated with human
development, especially livestock barns. This species is known to not only evict
bluebirds from nest boxes, but, given the opportunity they will trap and kill
bluebirds and their chicks in the nest box. Then, seemingly without a care in
the world, they will build a nest right over their victims’ lifeless bodies.
Bylane’s resident population of House Sparrows certainly had an impact on the
resident bluebird population. However I did my best to evict House Sparrows from
nestboxes as soon as they tried to establish residency. As a result, I managed
to allow only 2 House Sparrow chicks to be fledged compared to other years where
several chicks were fledged.
Photos Courtesy of and Copyright © by
Dick Budnik Photography
DickBudnik@verizon.net
http://mysite.verizon.net/DickBudnik
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