It was nearly 6 pm when I finally got to the park, and I expected nothing in the way of nature photos. But just out of habit I peeked over the edge along the eastside path. There, on the wet edge between rocks and water, flitted a little friend I hadn’t seen for almost exactly a year. The Spotted Sandpiper is said to be the most common sandpiper ever, and to breed just about everywhere along both coasts, but around the park it’s behaved mostly like a migrant visiting for the winter season. Three years ago, by way of exception, I saw it in August, possibly as part of a pair, in full breeding plumage showing the spots that give it its name. In the winter they’re immaculate (spotless), but continue to display the constant dipping/teetering behavior that is their all-season trademark.
These birds are among the small fraction of avians that practice polyandry. At least, some do. A recent study estimated that about a fifth to a third of the females observed mated with more than one male and laid more than one clutch of eggs, each from a different father. The females are able to store sperm for weeks before laying eggs. The females are bigger, heavier, and more aggressive than the males, and take on the job of defending the nest territories. The males sit on the eggs, which may or may not be the ones they fathered. This reversal of the more common sex roles is also found in some other shorebirds, such as several species of jacana, the common phalaropes, some snipes and buttonquail., as well as in some hawks, coucals, and woodpeckers. It is also seen in some fish and amphibians.