The Spotted Sandpiper has very few spots at this time, and they’re light. The spots come and go with the seasons, but the bird remains the same perpetual motion machine, always moving, constantly dipping its tail. Why the dipping? Bird experts still don’t understand it. Some birds do it constantly, other birds of about the same size with the same diet in the same environment do it rarely or not at all. I’ve seen Spotted Sandpipers along the west and south shores of the North Basin several times over the years. It’s good to know that they’re still present and active.
I’ve talked about their unique gender roles previously, but it bears another look. According to the Cornell bird lab website:
The Spotted Sandpiper is the most widespread breeding sandpiper in North America.
Female Spotted Sandpipers sometimes practice an unusual breeding strategy called polyandry, where a female mates with up to four males, each of which then cares for a clutch of eggs. One female in Minnesota laid five clutches for three males in a month and a half. This odd arrangement does not happen everywhere and often they are monogamous, with the female pitching in to help a little.
The female Spotted Sandpiper is the one who establishes and defends the territory. She arrives at the breeding grounds earlier than the male. In other species of migratory birds, where the male establishes the territory, he arrives earlier.
The male takes the primary role in parental care, incubating the eggs and taking care of the young. One female may lay eggs for up to four different males at a time.
Despite the gender roles, male Spotted Sandpipers have 10 times the testosterone that females have. However, that’s only in absolute terms. During the breeding season, females see a sevenfold increase in their testosterone levels, perhaps accounting for their aggression and the overall role reversal between male and female.
The female may store sperm for up to one month. The eggs she lays for one male may be fathered by a different male in a previous mating.
Its characteristic teetering motion has earned the Spotted Sandpiper many nicknames. Among them are teeter-peep, teeter-bob, jerk or perk bird, teeter-snipe, and tip-tail.
The function of the teetering motion typical of this species has not been determined. Chicks teeter nearly as soon as they hatch from the egg. The teetering gets faster when the bird is nervous, but stops when the bird is alarmed, aggressive, or courting.
The oldest recorded Spotted Sandpiper was a male, and at least 12 years old when he was recaught and rereleased during banding operations in New York.