Sunday 1st July comments: Visitors to the Isle of May have many questions for our staff on the island and one popular question at this time of year is “why all the empty snail shells?”, “Who eats the snails?” The answer…..Oystercatchers!
Oystercatchers have a varied diet, from probing the ground for worms, pecking limpets and barnacles from the shore line and of course the snails. They use their sturdy beaks to pick the snails from the walls and then suck out the body, either eating or feeding them to their chicks. Unusually for a wading bird, they also predate the eggs of other ground nesting species, such as Terns.
We have 19 pairs nesting across the island this year making a small scrape on the ground and lining it with a variety of items, some shells, others moss and some even rabbit droppings. They lay between 2-4 eggs (usually 3), hatching around twenty-five days later. It takes the chicks around thirty days before they can fly, until this time they rely on their superb camouflage to hide from predators.
It is also interesting to note the difference in behaviour between the pairs on the island. Some pairs will immediately make a racket and call loudly if you’re close to their nest, while others will slink away and rely on the natural camouflage of the eggs/chicks to protect them. The idea about making a racket and mobbing predators is that they are alarmed enough to vacate the area, while slinking away draws less attention to the presence of a nest. Two very different strategies employed by the same species on the same island – amazing!