African black oystercatchers
Did you know?
Oystercatcher numbers have risen slightly in South Africa thanks to an alien Mediterranean mussel that has proliferated locally, which they eat.
An odd thing about African black oystercatchers, apart from their somewhat bizarre appearance, is the fact that they almost never eat oysters. They hunt for food literally at the edge of the sea, mostly in the intertidal zone along rocky shores.
They eat mussels and limpets. Whelks, worms and periwinkles are all welcome, too. But somehow, oysters remain mostly ignored.
In fact, it would be more accurate to call these coastal birds 'limpetsnatchers'. On 1 offshore island alone, they’ve been found to remove an astounding 2.8-million limpets every year from only 2.5 km of rocky shore.
If you tried to remove a limpet, you’d need a chisel, a hammer and some serious muscle. So how does an oystercatcher, weighing about 700 grams and armed only with a sharp red bill do it? Adroitly sidestepping breaking waves, the oystercatcher approaches its unwitting prey from behind (yes, limpets can sense danger) and delivers a quick stab to the edge of its shell, knocking it from the rock.
After watching them for a while, you’ll develop a huge respect for the way they move around this zone of constantly moving water. A bonus is that they’re easy to see, being fairly large, with pitch black feathers and and dull pink legs, red beaks, and bright yellow and red eyes. From time to time they fly above the breakers with a loud insistent ‘kee-weeep’.
Often in pairs or a small group, they play daily chicken with the waves while hunting for limpets. Oystercatchers usually mate for life, and for them, life is comparatively long. Their lifespan is about 35 years.
One of the factors limiting their numbers is the fact that they breed on beaches in summer, at peak holiday season. Disturbance means that eggs or hatchlings are sometimes compromised. This has eased somewhat since vehicles have been prohibited on South African beaches since 2001.