RAVENS IN WINTER (379 pp., Summit Books, 1989; reissued in 2015)

From the book jacket: "Why 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."

REVIEWS (4.5 OF 5 stars on Amazon): "This inspired, fresh and fascinating report almost persuades us that this great bird of myth and legend is the most wonderful of all."—Peter Matthiessen

"A fine biologist (and fine writer) has done it again...Ravens in Winter is an endlessly fascinating book about those endlessly fascinating and intelligent birds."—Paul R. Erlich, author of The Birder's Handbook  

“Bernd Heinrich is no ordinary biologist. He’s the sort who combines formidable scientific rigor with a sense of irony and an unslaked, boyish enthusiasm for his subject, and who even at his current professorial age seems to do a lot of tree climbing in the line of research.” —David Quammen, The New York Times

"This is one of the best, most exuberant books I've ever read on how an academic field biologist actually solves a scientific conundrum."—E.A. Lovitt

What a wonderful book! I have never given much thought to ravens until now....Taking a cue from Heinrich, I plan on picking up road kill and tossing it in my yard to see if these interesting creatures will descend in my yard!"—M. Dillon


By 1984 I had come to the point in my studies of insect thermoregulation and bumblebee foraging behavior that my burning questions were starting to gel and consequently to cool. There was of course no lack of detail to pursue, but I felt that is what it would be: details. Major connecting threads were in place, and I was already writing summaries of the field, I did not have the passion to pursue questions whose answers seemed too easily predicted. Predictions and hypotheses now came too easily. But birds were of interest regardless of any active pursuits with them, and I had since a small boy at various times raised crows, jays and ravens to adulthood, and had been bonded to them, and vice versa. How eager I would have been to have an excuse to study crows, or ravens just to be near or with them! But there just seemed no compelling question that also lent itself to a technique to answer it.

Then something popped up as if out of nowhere: one day I was attracted to the remains of a moose carcass in the woods by seemingly distinctive raven calls that were different from the usual raven caws. I recalled the boar I had found as a young boy when we were living in the woods in a cabin in northern Germany. I had there heard ravens making a commotion as my sister and I made our way through the woods to the village school. I veered off into a spruce thicket, and there found food for our family: a partially-consumed wild boar. I presumed the raven calls I now heard in Maine meant the same thing—food. But since ravens were very rare in the neighboring woods in Maine I also wondered about something else: did the raven's calls also attract other ravens? This could be tested. It was a problem that had no current answer because it had not been asked.

I did eventually answer this question with the obvious tests. But every problem solved leads to several more; questions multiplied, the deeper I got into knowing the ravens in Maine. There had to be a reason why the ravens apparently recruited others, and by reason of what I knew they should not have been advertising for others to come and take their food away from them. They should instead have been silent. Now this really became exciting, and I knew that it would be a great adventure to solve this enigma.

No matter what the answer, it would be a great story and so in effect I began writing the book of it from the day it started, by taking meticulous notes every step of the way. It took me a year of the hardest physical and mental discipline to solve the puzzle to my personal satisfaction. I had in effect duplicated my bumblebee studies, but by an order of magnitude greater. I had captured hundreds of ravens and marked them with individualized tags (2 white, 9 red, etc.). I had built, with large crews of volunteers invited to parties with kegs of beer and roasted-over-the fire pigs, an aviary of gigantic proportion in my woods, and I had hauled tons of deceased/discarded farm animal carcasses into the woods and watched them from blinds made of spruce boughs for many days in the depth of winter. The answer to the enigma was that adult ravens paired "at home" in their territories defended their food bonanzas, but juvenile ravens that overnighted in sometimes distant communal roosts overpowered them by sheer numbers. Thus, it made sense for them to recruit in order to gain access to the food and to feed in safety.

The main question eventually left in my mind was how ravens communicated at the communal roosts of juveniles, for knowledgeable birds to follow them to a rich food resource where they needed them to help overpower defending territorial pairs. Did they do the analogous thing to the bee dance in the hive that indicated distance and direction to hive mates? The possibilities were inviting, but I left the problem to solve it in the aviary to an eager and highly capable post-doc and his wife, and invited them to live at my cabin with the aviary next to it. It had been built to solve this problem. I then left for a one-year sabbatical to Germany where I had been invited, after being offered a Humboldt fellowship because of my work with bumblebees. While there, though, I could no longer concentrate on the bees. I here spent most of my time finishing writing the book, Ravens in Winter. It chronicled my hardest Maine winter ever and the book was the detective story of my hardest-ever effort to solve a puzzle.