In order to facilitate the efficient exposition of difficult identification problems, a rigid format has been abandoned. Each ‘chapter’ has been arranged in the form of a ‘mini’ identification paper to best suit the topic under discussion. As it is important to be aware of the likelihood of any particular species occurring in a given area at a given season, each article is prefaced with a short section entitled ‘Where and when’, but it must be stressed that this is only a generalised outline that cannot account for every eventuality. Many accounts end with a short list of references. These point the way to books and articles that contain useful additional information or which go into various aspects of the identification in more detail.
Since the first edition, there have been a number of changes to English bird names, some of which have been widely accepted, others almost universally ignored. The names used in this book attempt to reflect current normal usage by ‘ordinary birders’ but, for the sake of clarity, some epithets (such as ‘Barn’ Swallow) have occasionally been used.
The rare breeding bird, scarce migrant bird and rare bird statistics have been taken from the official record published in British Birds (see Bibliography) and relate to Britain (but exclude Ireland). Their use attempts to quantify the likelihood of any given species being seen at a specific time and place. All are taken from the most recent reports: rare breeding bird data being accurate to 2010, the rare bird data to 2011 and the scarce migrant data to 2007. ‘Current averages’ are based on the most recent ten years. Waterbird counts are taken from the annual report Waterbirds in the UK and are accurate up to 2010/11.