Spotted Sandpipers are active foragers along stream banks and lake edges, walking in meandering paths and suddenly darting at prey—almost constantly bobbing their tail end in a smooth motion. Their flight style is equally distinctive: low over the water with stuttering bursts of fast wingbeats interspersed with very brief glides. Spotted Sandpipers were one of the first bird species described in which the roles of the males and females are reversed. Males are usually smaller, less aggressive and tend the nest and young. Meanwhile, the larger females fight for territories and may be polyandrous, meaning they mate with more than one male. Males that mate with the same female set up smaller territories within her territory and defend them against each other. Males tend to have more of the pituitary hormone prolactin than females. Prolactin promotes parental care, which may explain how the role reversal develops each season. The females perform courtship behaviour, usually an elaborate swooping flight with the wings held open while the bird gives its weet-weet song. She may also give a strutting courtship display from the ground. Females that are looking for mates over a wide area may do this up and down considerable lengths of shoreline. Interested males remain on the territory while uninterested males are chased away.
Photographer: Dave Saunders