This is one very angry tree swallow.
I went out to check our tree swallow trail and discovered that some of the swallows have selected their boxes. Our Peterson bluebird box on top of the hill had a half complete nest inside and the above photo is the male diving at my head trying to get me to keep my nose out of his nest box.
Two of the the other boxes were empty and the last house I checked, our Gilbertson bluebird box had a feather inside indicating that a male had selected this house as his own and was waiting for a female's approval.
Here is the feather inside the Gilbertson box.
When males are setting up their territories they will leave an object inside to distinguish that this is one of their possible nest sites. Females make the final decision as to whether or not it gets used. In early spring you can tell what bird species are considering your next box by their "calling cards". Here's some hints as to who has chosen your nest box:
Tree Swallows - a feather
Eastern Bluebirds - a piece of fine grass
Chickadees - a piece of fur or moss
House Wren - a twig
House Sparrow - piece of plastic or cigarette butt
I checked our wood duck box, there are now six, six eggs in the wood duck box (insert Sesame Street Count laugh here).