"I counted over 30 robins resting in trees in my backyard this afternoon."
Kim Yardy, London, ON (March 20, 2014) 

Migrating robins usually stay in flocks, which is one good way to tell if a robin you're seeing is a migrant headed farther north or one that is going to stay. Robins in the flock are antsy to move on. Suddenly, the whole flock will pick up and leave. In the air or taking off, they often give the "Zeeeeeup!" call, a contact call for migrating.

Photo: Kim Yardy