Denny checked the birds behind the store today and flushed a female blue-winged teal. Her nest is mere feet from one of the swallow nest boxes:

She has six eggs. I went out immeadiately after Denny told me about the nest and found it. Since she was still off I was able to snap a photo. When I went to check the nest that evening with Melissa and Lori we were not able to relocate it. She has done an excellent job of keeping it hidden.

This means we have the following known nests around the bird store:
4 - tree swallow
1 - hooded merganser
1 - black-capped chickadee
1 - house finch
1 - blue-winged teal