You may see white eyes or eastern turtledoves preening each other relatively often. Of course mates preen each other. Allopreening has advantages of not only preening each other's heads, where they cannot reach with their own beaks, but also strengthening the couple's ties through physical contact. Head scratching and stretching For grooming feathers on the head where birds cannot reach with their own beaks, they use their feet. The various groups use one method or the other, but most go for direct head scratching.
Small birds tend to scratch the head indirectly.
Even groups closely related to each other may groom the head feathers in different ways. For example, snipes prefer the direct method, and plovers the indirect. The black-winged stilt belongs to the group of snipes, but scratches the head indirectly. Considering other features, it is more closely related to plovers than snipes. Resting birds sometimes spread their wings horizontally or vertically to full span.