I won't pretend to know what the Jays were doing, but I did just happen to
read this very good article studying Jays' cognition/behavior yesterday in
Audubon:
https://www.audubon.org/magazine/march-april-2016/meet-bird-brainiacs-eurasian-jay
Perhaps this Jay was using these pebbles to mark caches or something? I'll
leave it to the experts...
brodie
