Book of the Month: Ravens in Winter

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Did you know that ravens are highly intelligent? Did you know that they have a large vocabulary of calls? Did you know that they recruit other ravens to share in a food bonanza they’ve found? Bernd Heinrich, one of my favorite wildlife authors, spent five winters studying the ravens around his cabin in the Maine woods. He was puzzled by the sharing behavior he observed, something that made no sense to him. Why, he asked, would a highly aggressive and territorial bird share its food? Beginning in October 1984, he was determined to find out.

Ravens in Winter is Heinrich’s scientific detective story, taking us step-by-step through his series of experiments to understand what the ravens were doing. He explores numerous possible scenarios, including tagging some of the ravens to understand which birds returned to caches and to differentiate juvenile from adult birds. He dragged a couple of thousand pounds of raw meat, carcasses collected from neighboring farmers, through the snow and up to mountain as he prepared sites where he could observe and record raven behavior. He and his students from the University of Vermont built a giant raven cage so that they could study a behavior more closely.

Reading this account gives us great insight into the working methods of a research scientist. It also hopes us understand the passion, joy, and heartache that Heinrich puts into his work. He compares his raven study to Sir Edmund Hillary climbing Mount Everest. If you consider the work he did slogging through three feet of snow, lugging groceries to the cabin along with dead sheep and calves, you’ll recognize what dedication to knowledge means.

In reading this account, you really get to know a lot about ravens. The common raven, Corvus coral, is common around Evergreen. I didn’t realize that it is rather rare in the northeast. It is a member of the corvid family, which includes the common crow as well as Clark’s Nutcrackers and Gray Jays in the Rocky Mountains. The corvid family also includes birds found throughout the world, including the hooded crow, the African brown-necked raven, and the Chihuahuan raven in the US Southwest.

In Heinrich’s account, you learn that ravens mate for life and vigorously defend their nest territory. At the meat caches Heinrich delivers, the resident pair is always dominant, frequently defending a cache against all comers. Young ravens avoid the resident pair unless they come in sufficient numbers to avoid confrontation.

Ravens, we learn, are superb scavengers. They eat all sorts of food, including one raven found with 285 Mormon cricket eggs in its stomach. They pick blueberries, eat at fast food dumps, and dig down to reach food buried three feet deep by hikers climbing Mt. Denali in Alaska. They hunt small animals, birds, and insects, and they cache food for later consumption. They go after larger prey as well, attacking deer fawns and young sheep. And, they raid the kills of other animals like wolves. They depend on wolves, mountain lions, or even coyotes to open the hides of larger animals so that they can get to the meat inside.

The Norse, Greeks, and Romans all considered the raven to be highly intelligent, as are the other members of the corvid family. The Roman naturalist, Pliny, describes how a raven dropped stones into a vase to lift the water from the bottom so it could drink.

Ravens have a variety of calls used to signal different types of behavior. Juvenile ravens wanting to be fed by their parents use a “yell.” When they are settling next to a mate, they make soft cooing softs. An angry raven gives a deep rasping call.

Heinrich also provides a series of sketches to illustrate the ravens’ body language. They raise the feathers around their heads to look bold and strong. They crouch down before dominant birds. They raise “ears” and look “fuzzy-headed” to challenge others. They strut with head raised and features extended like pants.

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Finally, as Heinrich is able to demonstrate, they recruit others to share food. Juvenile unattached ravens inform others at their nightly roosts about a food cache. They recruit the others to gain access to food that is being defended by the resident pair. The yell is a rallying cry to alert other juveniles to come and eat. They also recruit to show dominance. A juvenile raven practices being bold and strong at a food cache, a strategy that demonstrates to potential mates that this raven will be a good provider for their young.

The recruiting strategy is thus not only to get a gang to help overcome the resident pair, it is a strategy to show off in front to potential mates. Female ravens depend completely on their mates to bring food for them and small young for over a month during nesting. A male that is good at finding food is highly regarded as an excellent mate.

The next time you see ravens in Evergreen listen to what they have to say and watch their behavior around food sources. The dumpsters behind Safeway and King Soopers are good locations to learn more about raven behavior. You’ll probably find me there watching these extraordinarily interesting birds.

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Author: JoAnn Hackos

As a long-time birder, I’m interested in the health of birds and birding in the Evergreen community. I’m concerned about the affect of climate change on bird migration and the problems with declining bird numbers.

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