Ravens in Winter? by Bernd Heinrich (Author) Paperback:?379 pages Publisher: Vintage; Reprint edition (October 1, 1991) Language: English ISBN-10: 0679732365 ISBN-13: 978-0679732365 Product Dimensions: 8 x 5.3 x 0.8 inches Shipping Weight: 12.8 ouncesWhy should ravens--which are usually solitary birds--share valuable food in the dead of winter? How clever are these birds? Do they have a language? These are some of the riddles that noted sociobiologist Bernd Heinrich, author of Bumblebee Economics and winner of the John Burroughs Medal, explores in this intriguing book. 16 pages of drawings.
以下为对购买帮助不大的评价