Cornell has lots of interesting info: "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 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."
