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| Tree swallow sits atop a sparrow-proof nest box. |
House sparrows. You know the ones, those little brown and gray birds that have made themselves at home in almost every city on the planet. They were introduced to North America in New York in 1851, made their way into Canada twenty years later, and were in British Columbia by the turn of the century. Today it is estimated that there are just under 100,000,000 of them on this continent alone.
You may think of them as benign little birds that add a bit more life to an otherwise sterile urban environment, but nothing could be farther from the truth. They are cavity nesters, meaning that they look for holes to raise their families in, and will take nesting sites away from native species either preemptively or violently. It is not unusual for swallows, that also are cavity nesters, to be evicted from a site or killed outright.
House sparrows are about 50% larger than many swallow species. Their bills are heavier and capable of inflicting mortal wounds on their smaller relatives. This difference can be made to the swallow's advantage though by building nesting houses that keep their competitors out. You can see in the above image that the birdhouse has small openings that are semicircular rather than round and are small, being only 1-1/8" at the diameter. House sparrows cannot get through a hole that small. There are other methods from dissuading the invasive little birds from taking away valuable nesting sites.
If you are interested, read this blog: "invasive species spotlight house sparrow". It provides some interesting ideas. There is lots of information on the web and you can find videos on the subject on Youtube as well.
Thanks for reading.
Eric Svendsen www.ericspix.com
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