It is estimated that the Eastern bluebird population has declined by 90% in the last 50 years. These beautiful birds are cavity nesters (birds that may use artificial cavities such are bird boxes) so they are susceptible to competition from other cavity nesters like Wrens, Tree Swallows, House Sparrows and Starlings. They face the same threat that many native species confront, that of habitat loss due to current agricultural practices and urban sprawl.
Duke Farms started a nest box program in which we provide and maintain boxes to try and encourage the production and survivability of Eastern bluebird chicks. In 2015 we started to band chicks so that we could collect data on the health of the population that breeds here at Duke Farms. That year we banded 21 chicks and recaptured one as an adult at the MAPS (Monitoring Avian Productivity and Survivorship) banding station last fall. In 2016 we added 16 new boxes bringing the total bluebird boxes to 40.
Currently, this season we have 7 active bluebird nests and banded 26 chicks. This is the first of a potential three broods. While bluebirds are usually synchronous in hatching, this has not proved to be the case this year. We believe that this is due to the early season warmth in March followed by an unusually cold period in late April and early May.
The incubation period for Eastern bluebirds lasts anywhere from 11-19 days after which the eggs hatch. The chicks stay in the nest for 17-21 days and then fledge. We band them on day 10 or 11 so that the chicks tarsus (part of leg below the thigh) is fully formed before we apply the band. With such a short banding opportunity we have volunteers that monitor the boxes weekly and report progress to our Volunteer Coordinator and sub permittee, Clifford Berek, and our Ecological Specialist Michael Bellaus who then bands the chicks.
Additional information can be found at: https://www.allaboutbirds.org/guide/Eastern_Bluebird/id , The Cornell lab of Ornithology http://www.audubon.org/field-guide/bird/eastern-bluebird , Audubon http://www.nabluebirdsociety.org/ , North American Blue bird Society