Top Photo: Eastern bluebird nest with eggs.
There has been no activity in any of our six nest boxes. Though there are partial bluebird nests in the nest boxes at Explore the Wild and the east side of the parking deck, they haven’t be tended to for over a month. Likewise, the house wren nest in the nest box on the west side of the parking deck hasn’t been touched since June.
I tallied the total birds fledged for each year since 2012 and present them below.
There’s no data for the year 2020 due to Covid. There was no access to the nest boxes, the result of a complete nonessential shut-down of the museum.
The lower number of bluebirds fledged over time, and higher number of house wrens, has more to do with habitat change than house wren take-over of nest boxes. Open field or meadow habitat has been replaced by woods in some cases and new exhibits in others.
For those unfamiliar with house wren behavior, they tend to take over nests of other cavity nesting birds. The males arrive first in spring and may build one to several nests. They will go into an existing nest, remove the eggs and all nest material brought in by the original owner and build there own twig nest from scratch. When the females arrive they may use one of the male’s nests or build her own. The original nesting birds are the big losers here.
If chickadees and bluebirds, which are year round residents, build their nests early in the season they are less likely to be taken over by house wrens who are migratory and absent during the early part of the nesting season. Weather plays an important part in how early the locals construct their nests, but other factors play into it. A nest with nestlings already in it when the wrens arrive will probably not be taken over by one of the Troglodytes.
So, this is the final report on the six nest boxes on our modest bluebird trail here at the Museum of Life and Science. This year 24 birds have been added to the local avifauna, 17 eastern bluebirds, 4 Carolina chickadees, and 3 house wrens.
See you next spring!