Caspian tern does acrobatic manuvers with a fish in its mouth. It repeatedly flew over a flock of terns on the beach, occassionally stoping for a few minutes before flying around again. This bending-display is an integral part of courtship. (G. Thomas Bancroft)

A few weeks ago, I found a small flock of Caspian Terns roosting on the beach at Iverson Point on Camano Island. One tern seemed to not know that we are no longer in the breeding season. It was undertaking what looked like normal courtship behavior that males use to attract and form a pair bond with a female.

Holding a fish cross-wise in its bill, I watched a bird go through all the normal behaviors associated with courtship. He flew repeatedly low over the flock calling to the group below and flying higher to undertake the acrobatic “bending display” where he twists and turns upside down and side-ways heading strait downward toward the water just off-shore from the flock on the beach. Several times the male slowed as it flew over the flock, dropping to the sand and walking around among the resting birds.

A Caspian tern with a fish flies low over a roosting flock giving courtship calls to entice a female to follow. (G. Thomas Bancroft)

The only response I saw from the flock was when a few individuals responded somewhat aggressively by hunching their backs and heads, pointing their bill at the displaying bird. For pair bonds to form, females should respond to this display by following the male with a fish on a flight out over the water and eventually landing together on the sand where the male approaches the female, bows a few times and feeds the fish to the female.

I watched for 30 minutes and this male never ate the fish or successfully enticed a female to chase him and begin courtships initial phases. It was fun to watch even it was outside the normal breeding season. It never hurts to practice something so important as courtship and pair bond formation.