Results of 2012 Bluebird Box Usage

Tree Swallow perched on Bluebird box
Female Bluebird
Photo by Bob Stanowski

In the beginning of August all Bluebird boxes on White Memorial property were opened, inspected, and cleaned out. Unfortunately Bluebirds had a difficult breeding season, resulting in a 41% success rate. Weather was mostly to blame for this low percentage. Bluebirds start to lay their eggs in mid-April; and as some recall in the beginning of May this year we had lots of rain with unseasonably cold weather. This combination of cold air with damp conditions proved to be too overwhelming for the eggs and chicks; this became evident when we discovered many dead chicks and abandoned eggs. However Tree Swallows, who also use the boxes for nesting, had a positive season, with an 81% success rate, occupying most of the boxes. There were also twelve House Wren nests, half of which were constructed on top of Bluebird or Tree Swallow nests. Male House Wrens are aggressive and will destroy the eggs and young of other birds in order to use the nesting area. House Sparrows will also evict any nesting bird to take over the site, although only three House Sparrow nests were found in the boxes. House Sparrows are less tolerated around Bluebird boxes than House Wrens because House Sparrows are invasive species. First released in Brooklyn in 1851 from Europe, House Sparrows have become one of the most abundant and widespread songbirds in North America. Other unwelcome wildlife includes paper wasps found in five boxes and a White-footed Mouse in one box. In conclusion, 72 out of the 76 Bluebird boxes were active; meaning that a bird at least attempted to build a nest there, and of these 72, 70 were actually used to raise chicks.     

House Wren nest with six chicks inside stacked on top of a Bluebird nest

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