In my yard, House Sparrows have built nests in two bird houses
designed to allow Violet Green Swallows to nest but to exclude House
Sparrows. One of the houses has an openning on the front that measures
3 1/2 inches wide and 1 inch vertically, with rounded corners. The other
has a 1 1/2 inch round entrance on the bottom of the house. There is a 10
degree slope upward from back to front on the bottom. One more detail:
the entrances in both houses pass through a board 3/4 inch thick and the
margins of the entrances are rounded. The houses were purchased at the
Seattle Audubon Society office and were made commercially.
My question: Are the house Sparrows in my neighborhood in Wedgwood
smarter than others or have any of you encountered the same problem?