EPOW - Ecology Picture of the Week

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Sanderling Surf Toys

Credit & Copyright: Dr. Bruce G. Marcot

Explanation:  Dashing along the edge of seafoam on the wild Oregon coast is a flock of Sanderlings, a common, small sandpiper of sandy beaches.  Running like wind-up toys in the endlessly pulsing surf, Sanderlings chase waves to capture the small invertebrate prey that momentarily appears.   How do Sanderlings know to move in such unified motion?  If you've ever watched wheeling flocks of sandpipers and other shorebirds darting and swooping over some estuary, you have doubtless marveled at their ability to move as if with one mind.  It it telepathy?   The answer is more mundane ... and more amazing, in a way.  Flocking movement has been studied and better understood thanks to computer simulations.  Such studies suggest that subtle movements of lead or outer birds trigger following behavior by the rest of the flock, and that simple tendencies such as moving toward the center of the flock will induce different, "emergent" behavior of the flock as a whole.   Birds flock for predator defense, to share common resources, to allow access to mates, and other reasons.  Studying flocking behavior in birds -- even with computer simulation programs of "artificial life" -- can teach us much about human "flocking" behavior, such as behaviors of centralized organizational systems. So what seems to be one mind is actually a remarkably quick team response.  Next time you're on the beach, watch for this as flying or running flocks of birds (and people!) compress and "uncoil" as they wheel and dart along the surf.  Then think about how traffic jams compress and uncoil next time you're sitting on some freeway parking lot...