THE TAXONOMIC SIGNIFICANCE OF THE HEAD-SCRATCHING METHODS OF BIRDS.

Birds scratch their heads in one only of two ways, either directly or indirectly, and one method is used by all members of the same family though not necessarily by all families in the same order. When related families have different head-scratching methods, then the behaviour can help in disentangling difficult relationships. Examples are given. In the case of the passerines, only the Timaliidae (babblers) scratch directly. The implications are briefly discussed; for example, on this evidence Picathartes is not a babbler. The Psittaciformes are a potentially rewarding group for future work.