I spent time with this Spotted Sandpiper (Actitis macularius) yesterday afternoon. It kept a wary eye on me as it forged along the shoreline for insects and small crustaceans. Contrary to the name, the juvenile of the species lacks spots and instead has brownish breasts with a plain, white belly.
The Ancient Greek basis for the binomial is very descriptive; aktites = coast-dweller, macula = spot. Though, in my opinion, the key identifying feature is the bird’s constant body-bobbing, whether walking or standing still. This behavior led to the appropriate moniker, tip-tail.