Quote:
Originally Posted by covey ridge
Is that the correct size hole for swallows? In my youth I built a few houses with 1 1/2 inch holes and only got sparrows. It was a long time back, but I recall being told that swallows favored a smaller entrance, where they could enter and larger birds could not.
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The House Sparrows are small enough to fit in most boxes except Wren houses. You cannot exclude them by hole size. 1 1/2" should be good for the Tree Swallows, but is too small for Bluebirds. All the boxes in my yard are built with 1 9/16" holes because the research at the Joffre station had determined that Bluebirds will still squeeze in them but the Starlings will not be able to (unlike the Bluebirds preferred size of 1 5/8") so one would only have to worry about House Sparrows as predators on the nest. The Tree Swallows happily use the 1 9/16" holes. I had about 10 pairs of Tree Swallows this year - and the first successful hatch of Bluebirds since the big spring blizzard of about 6 years ago. One evening a few weeks ago I counted 45 Swallows on the power line in the yard.