By Ken Schwab
It’s springtime! If you decide to soak up the sun on a stroll along the Bay, you just might catch a glimpse of a territorial shorebird called the Black Oystercatcher (Haematopus bachmani). This shy bird is black with an orange bill and pink legs. The aptly named Oystercatcher feeds on mussels and other bivalves.
Who are the Oystercatchers?
The Black Oystercatchers are poorly understood, and a potentially threatened species. They have an estimated population of 11,000 living along rocky intertidal zones from Alaska down to Baja California, with ten percent residing in California.
These distinct birds are waders. They have long pink legs and black feathers. The further south they reside, the lighter their plumage becomes. Their body ranges from 16.5-20 inches and their wings span 28-36 inches. They weigh less than two pounds and exhibit sexual dimorphism, with females being longer-billed and heavier than males.
The Black Oystercatchers are monogamous and territorial during the breeding season. When they fall in love, these birds typically walk together while making novel calls. Eventually the couple may burst into flight and fly wing-in-wing around their territory.
When it comes time to reproduce, they make a single nest. Their nests are simple, created by digging a hole in a spot that can be monitored with ease. They lay one to four eggs. Incubation is a shared responsibility; however, the female usually spends more time perched atop the nest while the male protects the territory. Oystercatchers have also been known to ‘egg dump’, a practice that takes advantage of nests of other species such as seagulls. Once abandoned, the chicks will be raised by their new family.
When Oystercatchers get caught!
The Oystercatchers slurp down bivalves (oysters, clams, and mussels) with their strong bills. They will also prey on other shoreline organisms such as fish and crabs.
When foraging, they walk across shellfish beds scoping opened shells. When they find a juicy one, they quickly jab their long bladelike bill into the unaware shell, cutting the muscle that allows the shellfish to close. Some unfortunate birds, on occasion, are not quick enough and end up with their bill stuck in the rooted muscle, consequently sealing their fate as the hide tide immerses them in water.
Why are they important?
One species of oystercatcher became extinct during the 20th century, and the Black Oystercatcher is not far behind. The Black Oystercatcher is a keystone species along the North Pacific shoreline making their presence an indicator of overall health in the rocky intertidal ecosystem.
