I have a violet green swallow nest box hanging under the eaves. There
are currently three babies in there, now large enough to poke their
heads out the door most of the time.

This morning, four adult swallows were having a rather serious
confrontation in the area around the box. It looked like one pair was
fending off the other pair. I have also seen this behavior on the other
side of the house, away from the nest box.

I was wondering if this is common behavior. Do you know what it
indicates?

Thanks,
Geoffrey Jackson
Federal Way, WA
geoffrey at geoffrey.seanet.com