When a differently coloured line of feathers extends behind the eyes. A smaller spot is called a postocular spot [1]
References[]
^Garrigues, Richard and Dean, Robert (2007). Birds of Costa Rica. Zona Tropical Publication. ISBN9780801445873. CS1 maint: Multiple names: authors list (link)
This article is part of Project Glossary, an All Birds project that aims to write comprehensive articles on each term related to animals.