The Case of the Disappearing Oystercatchers

But there is trouble in paradise. Researchers have begun to notice a declining number of successful fledglings (a term for a juvenile bird who has learned to fly) on these islands. But mysteriously, these birds do not appear to be succumbing to starvation or the typical sources of shorebird nest predation (e.g. mammalian predators). In fact, researchers have yet to witness what is happening to these birds. They simply disappear, and are never seen again. What could be happening to them? And why is there no evidence of where they have gone? In the words of Arthur Conan Doyle's beloved detective, "the world is full of obvious things that no one by any chance ever observes."

Local researchers have brought a new wildlife observation method (already discussed in a previous blog post) to bear on this puzzle, wildlife camera traps. Their strategy? Deploy an array of trail cameras across the islands, one for every oystercatcher nest, one for every clutch of eggs. However, after a month or so of observation, one thing became clear: the oystercatchers didn't stay in their nests long once they had hatched. They quickly took to scampering along the island coastlines looking for food and testing their underdeveloped wings. This made tracking them difficult and time-intensive, as researchers quickly realized that the camera traps weren't going to be as helpful as they had first expected. Nevertheless, they left them out, in hopes that they might capture something, anything. Instead of completely relying on these cameras though, researchers took to keeping an eye on the birds themselves, watching them through binoculars every day while floating off-shore of the islands.

They kept up their vigil for weeks, taking special care to identify and track each fledgling every single day. However, not long after they started watching them, their beloved birds began disappearing, one by one. Each day, as they took to counting their subjects, they were forced to record fewer and fewer birds. After less than two weeks, all but one of them had vanished. What had happened? They had observed no predators during their vigil: no hawks, raccoons, or otherwise. Perhaps they had simply starved? Frustrated and perplexed, they went ashore to try to see if there was any evidence of where the birds had gone. But there was no sign of the birds, no obvious evidence of predators, no corpses, no feathers, nothing. So, they gathered up all of their trail cameras, and left the last bird to its fate. Their last course of action was to go through the thousands of images on each of the trail cameras: a task that could take months.