Birds of Saudi Arabia: Eye colour of juvenile and adult Clamorous Reed Warblers

2 Jan 2014

Eye colour of juvenile and adult Clamorous Reed Warblers – Alba Marsh (Bahrain)

Whilst ringing at Alba Marsh Bahrain we have caught and ringed over 50 Clamorous Reed Warblers. As the species is mainly sedentary, and the marsh is a small size, we re-trap quite a number of birds each year. This allows us to confidently age them as adults if the re-trap date is more than one year after original trapping. Although we have not done a scientific study of the birds it has become apparent that the eye colour of Clamorous Reed Warblers alters with age from a dull grey brown to a rich brownish. This has been noted before in European Reed Warblers (Karlsson K, Persson K & Walinder G 1988: Var Fagelvard 47 : 141-146) although we were unaware of this paper when we first thought the eye colour may change in adult birds. We have little data on Clamorous Reed Warblers and so this appears it may to be a good way to age birds. We will continue monitoring this as well as checking tongue spots and tarsus colour as this is also mentioned in the paper for European Reed Warblers as ways to help with ageing.