We think of eastern bluebirds as gentle birds. They seem to be poor fighters and often lose battles with house sparrows and starlings, so I was surprised to learn from Karen DeSantis that she witnessed two male eastern bluebirds in a long ferocious fight in late February a few years ago.
Karen described on PABIRDS how the fight began with chasing, then escalated into periodic knock downs and grim combat on the ground. The males fluttered and rolled over a distance of about 30 feet while the female followed every move, twittering as she watched. The birds were so oblivious that Karen was able to take photographs of the 15-minute battle. Karen wrote, "It was the long duration of the fight that interested me the most."
Though we might not realize it, these battles are consistent with bluebird behavior.
During the winter bluebirds flock in family groups and huddle together to stay warm. In early spring their togetherness ends as the fathers eject their sons from the group before 'Mom' and 'Dad' nest again.
But the battle Karen witnessed was not a mild family squabble. Its intensity indicates the guys were fighting over the lady.
Bluebirds are usually monogamous but about 20% of the young come from extra-pair copulations. The males seem to know if their ladies' eyes are wandering and guard their mates more closely if they've been messing around. According to Birds of North America Online, "Experimental evaluations (Gowaty 1980) indicate male-male aggression most likely serves to protect threatened paternity. Males are aggressive to males usually in defense of paternity." These battles can be so intense that they end in the crippling or death of one of the birds.
Bluebirds may seem gentle but don't mess with their mates! Click on Karen's photo above to watch a slideshow of the fight.
(photos by Karen DeSantis)