A female Tree Swallow defends her box from an intruding female that may also want the box.

This video taken with an in-box camera shows a resident female Tree Swallow successfully defending nest box against an intruder unfortunate enough to be caught inside the box. It is quite violent and disturbing to watch, but the intruder survives. This behavior is also seen in bluebirds, wrens, chickadees and other cavity nester which compete for nest cavities they can't make themselves.
Video from Francois Paquette of QC. Edited by Chris Gates of NY.
For more on tree swallow nest site competition see:
treeswallowproj...

[@GuShuJuin]

Thank you for sharing this video because I could not figure out and so confused about what these birds were doing at the nesting box in my yard. The couple had 5 eggs in the nest and they always constantly had so many visitors flying around the box. Now I know the visitors are foes instead of friends and they were fighting seriously.

[@starlynhoward7068]

This is absolutely fascinating....I have been monitoring tree swallows for several years, but to see what they are doing INSIDE is so interesting!

[@alicejohns9852]

I have a nest in my box with 5 eggs in it from my back yard tree swallow. I love to watch them every day. this information has been good since I had some babies in there last year and now I know about how long it will be before I see my resident family. I only had 3 eggs last year and one bird died after it hatched. I think it got suffocated by the others. I have some great photos of them and even had a bird book made up of them through Shutterfly. They are a joy to watch and I have it positioned so I can see it from my bedroom or living room windows. I am listening to David while I type.... learned another thing. I had no idea that the mother bird ate the egg shells!!!