There are about 11,000 Black Oystercatchers along the north Pacific and about half are found in British Columbia. Raising young oystercatchers through the perils of seashore life often ends in failure. Recent research by Stephanie Hazlitt at Simon Fraser University shows that nesting is arduous with few oystercatchers surviving to become adults and she suggests that oystercatchers have adopted an insurance policy when it comes to raising their young. Some nesting territories have much better feeding areas than others - prime real estate for an oystercatcher is a low sloping beach with lots of the oystercatcher's favourite prey of limpets, chitons and mussels. One suggestion is that the additional egg is an insurance against the loss of the first or second egg.
Oystercatchers often nest on small rocky islets away from most predators.
They can be sensitive to disturbance and will let you know in no uncertain terms. Well-meaning boaters and kayakers are often the worst offenders. Do your part by avoiding these sites and watch from a safe distance. Many animals are very choosy when it comes to selecting a mate because it can be the difference between raising young or not. Over a century ago, Charles Darwin suggested that females are generally the choosiest sex and her choices explain such elaborate ornaments as over sized antlers in elk and moose, and elongated tails in peacocks.