Barbara, my experience here in Benton (near Waterville) is the blue
birds come first and take some boxes. About two weeks the tree swallows
come and chase the blue birds out of the boxes. The tree swallows come
here about 2 weeks after they are seen by Jeff Wells in Gardiner. They
arrive around April 9 (2012, 2014) to 18th (2020). The barn swallow
arrive here between April 25 (2011) to May 14th (2012). Spring is
coming. I saw a lot of red winged black birds and grackles Friday 12th
Bailey Island harbor. /Allan