“Q: On my way home from school I saw a robin loudly chirping at a sharp shined hawk perched in a tree. Wiki says sharp shined Hawks eat thrushes and robins are thrushes so maybe the robin was trying to scare off the Hawks?”
You’re absolutely right! Mobbing is a behavior common in birds, where prey species will try to drive a predator away with lots of screaming and bullying. Robins specifically will only mob/attack during breeding season, but they will yell at things year-round
Photo from ECOLOGY NGĀTAHI
Mobbing is actually a really cool and complex behavior, for a couple of reasons. A bird of one species will spot the predator, and start giving off an alarm call. Not only does this bring in any others of the same species nearby, but often these calls bring in other species as well.
WHICH IS RIDICULOUS. How often do you hear about interspecific communication? It’s one thing to understand what others of your species are saying, but chickadee alarm calls have been recorded at eliciting a response from at least 10 other species. That’s like you and your cat sprinting down the street because you know the neighbour’s dog is barking at a burglar and not just a quickly-moving squirrel. AMAZING
Some other cool things:
Photos from Wild Birds Unlimited, Eileen, and Daily Mail.