Tree Swallows
I've been taking a tour of the conservation areas in Wrentham, and I found my favorite one so far... the Birchwold Farm conservation area in West Wrentham. It's 129 acres with plenty of trails and a pretty good variety of terrain and wildlife.
In the open field near the parking area there are a bunch of bird boxes and there were a few tree swallows gathering food and bringing it back to their babies. Of course I didn't see the babies, because they're inside the box, but I did hear them. The odd thing about this was that there were three birds that seemed to all be bringing food to the box I was taking pictures of. There was a small scuffle between two of the birds, so maybe the third bird wasn't welcome.
Here's a link to a brochure that has maps and a brief description and history of all the conservation areas in Wrentham. Wrentham Guide to Open Spaces and Conservation Lands