The major field guides for identifying birds offer only general data on geographical and seasonal distribution; for specific information serious birders must rely on state and regional studies. Johnsgard has provided a comprehensive and up-to-date guide to the avifauna of a region previously poorly covered, the northern Rockies between the 40th parallel in northern Colorado and the 52d parallel in central Alberta, with a strong focus on national parks. Arranged taxonomically, the 354 species accounts include maps, latilong charts, and brief descriptive texts. Authoritative, clearly written, and easy to use, this guide is essential to anyone who wants to know the region's bird life. Paul B. Cors, Univ. of Wyoming Lib., Laramie Copyright 1986 Cahners Business Information.