Late yesterday afternoon, the clamor of chickadees, punctuated with a few nuthatch calls, revealed the presence of a N. shrike on the bluff-side edge of the small lake at Crosby Park. The chickadees surrounded the shrike at a fairly close distance, flitting nimbly away as the shrike moved casually through upper branches, stopping to perch here and there. It reminded me of crows mobbing a Great-horned owl, and raised the same questions. Aside from the species-survival value of a warning system, isn't this risky behavior for the individual birds? Do they engage in it selectively, as when, for example, they've witnessed the predator has just eaten, and is unlikely to hunt again? Is such a racket likely to drive off a predator for its ability to foil a sneak attack? Are they using the "safety in numbers" concept to confuse and tire the predator? I wish I'd had more time to follow the course of events. Linda Whyte
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