The oystercatcher (Haematopus ostralegus) is the only species of wader that has become a genuine urban bird. It forages for food, namely earthworms, on urban lawns and nowadays occasionally nests on flat building roofs. There is a breeding population consisting of a few pairs of oystercatchers on Harakka island, where the birds build their nests near those of common gulls and often right by the island’s many trails.
Female oystercatchers usually lay three eggs, whereas other waders always lay four. Oystercatchers are quiet in their nests while incubating their eggs, but start making warning calls similar to a train whistle once the chicks hatch. Both the male and the female stay with the chicks for over a month, or until the chicks learn to fly. Unusually for waders, oystercatchers also feed their young, whereas the chicks of other waders have to find their own food.
Photo Jussi Helimäki.