By Charlotte Owen
There’s no mistaking the oystercatcher, one of the largest, noisiest and arguably best dressed of our shorebirds. Its smart black-and-white dinner suit is offset by a day-glow orange bill, bright red eyes and pinkish legs in a stylish ensemble that hints at an expensive taste for fine dining. The oystercatcher is probably the only wading bird capable of cracking open an oyster, thanks to the incredible strength of that orange bill, but oysters are not often on the menu here in the UK. Instead, oystercatchers feed on a wide range of other shelled prey from cockles to crabs, mussels, limpets and whelks, and will also probe the sand and mud in search of worms. Individuals will usually specialise in either crunchy or soft-bodied prey, and their beaks adapt accordingly.
Oystercatchers that focus on shellfish will either prise them open or smash them apart, and young birds seem to learn their trade from their parents during an apprenticeship that can last up to six months. Their chosen method helps to hone their bill into the perfect tool for the job: a chisel-shaped bill-tip for prising, or a blunt-ended bill to hammer a shell until it cracks. In contrast, birds that specialise in probing for worms have pointed, tweezer-like bill-tips for grasping slippery, soft-bodied prey and their apprenticeship is far shorter, since it’s a much easier technique to master. Their choice isn’t set in stone though and individual birds can swap between feeding techniques when needed. An oystercatcher’s bill grows so rapidly, at a daily rate of 0.4mm –three times faster than our fingernails and equivalent to one complete bill-length every six months – that when switching from a diet of shellfish to lungworms it takes a mere ten days for a bird’s bill to morph from chisel into tweezers.
Since all of the potential feeding methods require considerable time and skill, some enterprising individuals choose an alternative option and become professional pirates. The oystercatcher’s heavy bill makes a formidable weapon, perfect for a spot of swashbuckling with unsuspecting neighbours, and successful bandits manage to obtain about 60% of their food by attacking other waders and stealing their lunch.
oystercatcher in flight © Derek Middleton