In an earlier post, a Red-breasted Parakeet (Psittacula alexandri) was shown scratching its head by the direct method of raising its foot from under the wing. This is characteristic of terrestrial birds.
In this post, Choo Teik Ju photographed a Barn Swallow (Hirundo rustica) scratching its head by the indirect method. Here, the leg is extended over the wing in order to reach the head. This method is common among arboreal birds.
This post is a cooperative effort between NaturePixels.org and BESG to bring the study of bird behaviour through photography to a wider audience.