This booklet presents pheonological data from nine bird observatories around the UK. A total of 39 species were chosen to include as summer migrants in this guide, with at least five years worth of observation data being included (covering 1974-1978). For a few species ten or fifteen years of data have been included. Accompanying each histogram is a page of text which outlines and discusses the pattern displayed. The text is mainly confined to a discussion of the observatories' data, but outside references have been used where these throw light on the patterns illustrated.