Just Wondering: How do birds tell each other apart?

If you’ve ever looked at a flock of seagulls at the beach, or a group of penguins huddled on the ice, you’ve probably wondered how they tell each other apart? To the human eye, they look completely identical. But in the animal kingdom, mistaking a stranger for your mate, your chick, or a rival can have disastrous consequences. Dr. Leslie Phillmore, a Professor of Psychology and Neuroscience at Dalhousie University, spoke to Andrew Carter.