Brainy Birds

Common Ravens, public domain
Common Ravens, public domain

At one time in my life, I was a (very minor) celebrity. I had only a handful of fans, but they were loud, devoted… and covered in black feathers. If they had spoken English, they would have cried out at my arrival: “She’s here! It’s really her! It’s the mouse lady!”

I was working at a facility that housed birds, including 3-4 Common Ravens in large outdoor aviaries. The aviaries were huge and enclosed on all sides with heavy wire mesh that kept the birds in and predators, like cats and hawks, out. Because predators were excluded and there was an abundance of bird seed and other goodies on the ground, the aviaries were a haven for mice.

Mice can carry Hanta virus, and will even eat disabled birds, so they were not welcome in the aviaries. I decided to put a dent in their population using snap traps. Every morning I collected a grisly pile of mouse corpses from my traps. It was disgusting. A few days into my mouse eradication campaign, I decided that instead of tossing my dead mice in the trash, I would give them to the ravens.

Common Ravens will eat just about anything, but they love carrion. I thought the captive ravens might enjoy a treat, so I pitched the day’s mice into the ravens’ bowl. The next morning they were gone, only some leftover dog kibble remained.

After a couple of days of receiving mice, I noticed that the ravens got excited whenever I arrived. They flew from perch to perch and croaked excitedly when I appeared. The other people that worked in the aviaries never got this greeting, not even the woman that fed the raven their daily ration of dog food.  The ravens seemed to recognize me, regardless of what coat I was wearing, or if I had a hat or sunglasses on.

While I liked to joke about how the birds knew and loved me, scientists have recently shown that the Common Raven’s smaller cousin, the crow, does indeed recognize individual human faces, and it is likely that ravens can too. In fact these birds are capable of some impressive intellectual feats.

Bernd Heinrich, a biologist who studied raven behavior extensively and wrote the book Ravens in Winter, devised a clever test of raven intelligence. He tied a long piece of string to a branch and attached a piece of meat to the end of it. When a raven perched on the branch, the long string let the meat dangle of out reach below the bird.

But the raven solved the problem. The bird would reach down, pull up a length of string, lay it against the branch and step on it to hold it.  Then it would pull up another length of string and hold it, effectively reeling in the sting until it could reach the meat. Heinrich tested multiple adult ravens and they not only solved the problem, they did it without using trial and error. The birds appeared to study the situation, think through possibilities and then quickly reel in the meat.

Ravens also have a good memory. They cache, or hide, food to eat later and because they have a lousy sense of smell, they need to remember where they put it rather than sniff it out. Young ravens will practice caching by hiding inedible items, they also practice another favorite raven trick– stealing each other’s caches.

Through a series of careful experiments, Heinrich and his colleagues were able to show that ravens can learn which individuals make a habit of stealing caches and they will wait until the thief cannot observe them before hiding their treat. Ravens can also attribute knowledge to other individuals and predict their actions. In other words, Rick the raven knows that Betty also saw where Cindy hid that tasty bit of rabbit. Some animal intelligence experts believe that the raven’s smarts are comparable to those of chimpanzees and dolphins.

So if you ever get the feeling you’re being watched by your neighborhood ravens, you’re probably right. They know your face and they probably know that Wednesday is trash day and that the Walkers have usually have roast chicken on Tuesday so there will be good leftovers in the bag at the top of the can.

This article was originally published in the Grand Junction Daily Sentinel on October 25, 2015

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Brainy Birds

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