Tenen

The most well-known is probably the Sanderling. The attached photos of Sanderling and Purple Sandpiper clearly show that the former lacks a hind toe. That doesn’t stop this little sandpiper from frequently running at high speed along the shoreline. In the case of the Purple Sandpiper, a small hind toe is visible. This comes in handy when clambering over slippery basalt rocks in search of food.