Oysters can’t run, so why are these birds named “oystercatchers”? Here they’re at work demonstrating their technique for opening mussels. They make it look easy. Placing the shell on the rock, with the mussel’s muscle down, they insert their razor-sharp orange beak into the crack and wedge the shell open. The mussel seems to know it’s lost the war, relaxes its muscle, and opens up.wide. Then it’s gobble, gobble and on to the next. No trouble at all.
Compare this technique to the crow’s, as seen in this earlier post. The crow’s beak looks sharp, but it’s rather soft. It’s good for grabbing, like a pair of pliers, but it’s no good as a chisel or a wedge. So the crow has to pick up even a small shell and drop it from a height on a hard surface to break it. That’s a lot of effort. The oystercatcher could probably polish off five clams in the time it took a crow to eat one. But shellfish are only a small part of the versatile crow’s diet, whereas the oystercatcher’s menu is limited to a narrow scope of intertidal invertebrates.
Oystercatchers are said to have another method of opening shells, namely simply hammering on them with their beaks to break them open. I haven’t seen them do that here but will watch for it.