Presentation of the Belgian Bird Definitives. A Flock of Kiewiets , by Annette Kiewiet de Jonge. Interesting presentation of the Northern Lapwing. Mike Duggan Site devoted to Owls on stamps. Aves Philatelicae Scandiae French Topical Philately Association Bird stamp catalogue Fauna Birds , published by Domfil autumn 1999.
All text is in both Spanish and English.
The stamps are listed by country. Identifiable birds are listed with their Latin names. The catalogue is very comprehensive. Birds not easy to identify are included with names like dove, duck, bird etc. Online Linn's has a new issues page with detailed description of all new and recent stamps of the world.