We have been observing some rather disturbing behavior by House Sparrows.
We have several Violet-green Swallow boxes that have been used successfully
over the last few years. This year, House Sparrows (usually the male,
sometimes female too) have been perching on the boxes and calling. They
can't use the boxes, but it is preventing the swallows from freely going in
and out of the boxes. I am concerned that they may not be able to breed
successfully this year. I also heard some commotion in a large tree on our
property and saw a female House Sparrow actually biting a chickadee on the
back of the neck.

I have not previously seen such aggressive and harassing behavior by these
interlopers.