Having recently discussed the addition of Slaty-backed Gull to the Thai list, it seems only natural to talk about this excellent book which attempts to deal with all the races of large gulls that have caused so much confusion over recent years, as well as all the other, more well-understood gull species.
A large book, and not cheap to buy, but certainly the most up-to-date and comprehensive book on gulls currently available. There are detailed sections on all species with colour plates and many photos for each species and race. Without this publication birders have a limited chance of separating birds such as Slaty-backed Gull, Heuglin’s Gull, Vega Gull, Herring Gull, Mongolian Gull, Caspian Gull etc. The photos of Slaty-backed Gull in this book certainly prove that it would have made identification of Thailand’s Slaty-backed Gull relatively easy had it been available to the observers.
I have been using this publication for nearly 2 years now and it helped me get to grips with Yellow-legged, Caspian and both argentatus and argenteus races of Herring Gull in UK; hopefully it will help me find species such as Mongolian Gull, Slaty-backed Gull, and perhaps others, in Thailand.
Whilst very helpful in learning about tricky to identify gulls, the number of difficult to separate species and details on moult pattern can be confusing. It is also worth noting that this publication is not the final word on gull taxonomy and there are likely to be more splits in the future; fortunately all the races known are covered here and if and when any are split it will be fairly easy to understand what has happened.