This is a richly illustrated photo guide with over 1400 pictures of handheld birds. It covers 62 East Asian passerine species, including many that appear as sought-after vagrants in both Europe and North America. The book's content, both photos and the thorough text, stems from the collaborative project that the Swedish and Chinese ring marking centers carried out in Beidaihe, Hebei province (northeast China) during the years 2011–2013. As a result, the book is bilingual with English in the left and Chinese in the right column.

This book is a must for ringers / banders as well as all dedicated spectators who like field determination of mis-flown Siberian birds! Never before have our beloved Eastern jewels been treated in such detail!

As the title indicates, the age and sex determination of migrating East Asian birds is described, most of which have also been found in Western Europe. The book connects in a pedagogical way molting patterns (how and when the feathers are changed) with costume characters that form the basis for determining an individual's age and gender during both autumn and spring. The content of the body text is then followed up in the rich photographic material where the captions address the most important feather details that guide the reader through the age and gender determination process. For several of the species that are treated, completely new and previously unknown data are presented here, and for other species, previous misconceptions are corrected.

Each species presentation begins with a number (up to five) full-body images to reflect the species' costume variation. A short piece of text summarizes the breeding and winter distribution as well as the occurrence at Beidaihe. This is followed by a section that deals with the species determination (distinguishing from other similar species).

In addition to the book's main chapter, there are also a number of appendices where the species determination of particularly difficult species groups is discussed in more detail. And in the introduction you will find an unusually easy-to-understand overview molt patterns, and how this can be used to determine the age of the birds.

Treats the following species (alphabetical order): Amur bush quail, Amur warbler, Amur warbler, Amur thrush, finch, finch, blue nightingale, blue and white flycatcher, brown hawthorn, brown warbler, brown thrush, drill nightingale, sparrow warbler, dwarf sparrow, gray sparrow, gray sparrow, gray sparrow thrush, greenish, yellow-breasted sparrow, golden thrush, golden sparrow, heather pipit, Chinese thrush songbird, kingbird, kingbird songbird, mandarin tit, mingling thrush, mugimaki flycatcher, northern songbird, splendor sparrow, ruby nightingale, reddish sparrow, red-breasted sparrow puffin, Siberian pipe lark, Siberian thrush, catfish, greater pipe lark, black-breasted reed warbler, black-backed red-tailed deer, taiga blue-tailed deer, taiga flycatcher, taiga warbler, pine sparrow, thick-billed warbler, tristram sparrow, marsh warbler, tundra pipit, willow sparrow, willow warbler, white-breasted narcissus flycatcher, white-throated thrush, meadow sparrow, eastern crowned warbler, eastern great tit.