Rouge Valley Conservation Centre


Eastern Bluebirds
at the Rouge Valley
Conservation Centre

By David Lawrie

The introduction of non-native species.

The house sparrow and starling introduced from Europe in the early 20th century have impacted bluebirds to a large degree. House sparrows in particular are very aggressive and they are also cavity nesting birds. They dominate the more timid bluebird, taking over bluebird nests, destroying the existing nest including any eggs or baby bluebirds in them. House sparrows are also highly aggressive and protect the areas around their nests, limiting the use of nearby nesting sites by the bluebird. The rapid expansion and population growth of this introduced species has made it very difficult for bluebirds to compete and survive. 

The use of DDT and other pesticides.

While the overall effects of DDT and pesticides on bluebird populations is debated, there is a general acceptance that there has likely been a negative affect of these chemicals on bluebird populations.

Bluebird Box at Rouge Valley Conservation Centre with Bluebird nest and eggs. Photo by Bill Lewis.

March 22, 2009

The North American Bluebird population suffered a major decline from the 1920's to the 1970's. At the lowest point, most estimates indicate that the Eastern Bluebird population fell by 90%, across its range.  As with many cases of wildlife decline, there was a combination of causes for this problem:

The reduction of natural bluebird nesting sites.

Bluebirds are cavity nesters, but their beaks are not strong enough to excavate their own nesting cavities, so they must utilize pre-existing nesting cavities or holes in trees. Historically, the bluebird would find these places in rotting logs and standing dead trees. Sometimes the bluebird would take up residence in old woodpecker holes. However the elimination of woodlots and the removal of standing dead wood on individual properties has reduced the amount of nesting sites
over time.


Learn more about the Eastern Bluebird from the Cornell Lab of Ornithology click here.

For more Eastern Bluebird information, click here.

To watch an Eastern Bluebird nesting in Greenville, Texas on March 19, 2009 click on the video below.

Bluebirds at the Rouge Valley Conservation Centre.

Bluebirds require a natural cavity to complete their lifecycle and have difficulty finding this habitat in an urbanized area such as Toronto where there is limited habitat available for nesting. In the Rouge Park, historically there were many blue birds, however by the 1980's many people under the age of 40 had never seen a bluebird. Even today, there are still many people in Toronto who have yet to encounter a bluebird. Through our Cavity Nesting educational program at the Rouge Valley Conservation Centre, visiting students have built about 200 bluebird nesting boxes and we have installed them at the Rouge Valley Conservation Centre and surrounding area, providing bluebirds with a suitable place to nest within our urban area. These boxes are

monitored and maintained by Bill Lewis and Steve Gahbauer who have played a key role in the success of maintaining bluebird habitat at the Centre, with the assistance of the Toronto Zoo.

Since 1998 we have averaged approximately 10 pairs of bluebirds per year and in 2008 a single pair of bluebirds successfully produced two broods, totaling eleven young. The first brood produced 6 young and the second produced 5 young. Making the Rouge Valley Conservation Centre one of the only locations within the City of Toronto where you can observe a blue bird on a regular basis.

Although introduced non-native bird species can be a problem for bluebirds, the more aggressive Tree Swallow appears to be the major bluebird competitor for nesting habitat in the Rouge Valley Conservation Centre area. These swallows often usurp nesting boxes either before the bluebirds arrive, or out-compete them when they do. However, once a Tree Swallow pair is established in a nesting box, it usually no longer takes much notice of bluebirds in a neighbouring box. Learning this from the observation of bird behaviour, we often place bluebird boxes in groups of two – one for swallows and one for bluebirds as both bird species appear to tolerate each other’s presence even in close proximity.

Across North America Eastern Bluebirds have started making a recovery due to volunteer actions such as the installation and monitoring of nesting boxes, and encouraging others to get involved. At the Rouge Valley Conservation Centre, Bill and Steve continue to do their part and visiting students continue to build nesting boxes and await the arrival of the bluebirds this spring. Come and visit the Rouge Valley Conservation Centre and see them for yourself!

Bluebird observed in February 2009 just south of the Rouge Valley Conservation Centre. Photo by Bev Edwards.

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