A pint-sized Northern Pygmy-Owl, not much bigger than a pine cone, hoots from a tree-top on a winter morning. Before long, this diurnal owl - a determined predator of small birds and mammals - will attract a mob of a dozen or more small birds. Mobbing may be a collective response to danger. But it's not certain if the "mobbers" hope to drive away the predator, or simply draw attention to the threat.More info and transcript at BirdNote.org. Want more BirdNote? Subscribe to our weekly newsletter. Sign up for BirdNote+ to get ad-free listening and other perks. BirdNote is a nonprofit. Your tax-deductible gift makes these shows possible.