Friday, April 17, 2015

House Sparrow and Tree Swallow

On Tuesday I watched House Sparrows and Tree Swallow compete to occupy bluebird houses. Last year I wrote about Tree Swallow and bluebird interactions. Swallows also compete with House Sparrows. In the late 1800s, House Sparrows spread across the country. I have also blogged about this phenomenon. This rapid range expansion is somewhat paradoxical, since local House Sparrow populations tend to be relatively sedentary. Apparently cities and towns served as islands of safety for the expanding House Sparrow populations—islands that lacked occupants of the niche that sparrows occupy. Lowther and Cink (2006) write that, if you want to discourage House Sparrows’ supplanting bluebird or swallow nest boxes, then you should place the boxes at least 100 meters from farmyards and other sparrow habitat (such as livestock pens).

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