Relict Gull, Kazakhstan (© N. Voaden)
The Introduction starts with a section offering advice on the best ways to approach gull identification and providing a comprehensive glossary of terms used in the book, along with photographs highlighting and naming the various feather tracts that are important for identifying gulls. This is followed by a comprehensive section detailing how to age gulls and explaining the relevant facts about moult and its impact on identification.
This book uses ‘cycles’ to describe age classes, instead of terms such as ‘first winter’, ‘first summer”, which are probably more familiar to most readers. Terms such as 'first cycle' and 'second cycle' are preferred because the plumage changes gradually, especially in large gull species with protracted moults. During the first cycle, for example, most taxa undergo a protracted partial moult between late July and the following May, which may be slower, or even suspended, in parts of the winter. There are of course some exceptions (Iceland, Glaucous, Audouin's, Pallas's, Baltic and Heuglin's Gulls) that are explained in detail. For each taxon covered, the description goes through the various cycles, showing the variation and comparing with adjacent photographs of similar-looking taxa.