Great point! Blue birds seem to get all the attention and I love them also but tree swallows are native species and should be given the chance to share the habitat along with blue birds.
Lots of folks get upset if tree swallows move into the blue bird houses.
I did a bit of research and decided to try this method. Put two boxes on the same pole. A nesting blue bird pair would not tolerate another nesting pair of blue birds that close in proximity and vice versus, but they will tolerate a different species. Over all I have had good results with this method as illustrated in this photo from my land. Both species were successful in raising fledgling's that season.
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