Nevermore

There I was running down the street when I heard a call from the trees.  The telltale heart of a…I mean the telltale call of a Common Raven.  I’ve actually not seen ravens around here before, but this call (and the bird I looked up to see) was definitely a raven.  I was quite surprised (and secretly pleased).  The call of a Common Raven sort of sounds like a crow with a frog in its throat (which may not be inaccurate, either).  It’s sort of a gravely ‘cwawnk’.

When I lived in California, I was used to seeing ravens all the time.  They’d fly over with their noisy feathers and scare off the crows.  In most places around town, you’d find both species arguing over garbage and moving through the neighborhood.  Here in Charlotte, it’s really just the crows.

Like other Corvids (the family that includes crows, jays, magpies and ravens), Common Ravens are interestingly smart birds.  They have good spatial and good social skills and seem to have some ability to problem-solve.  The “interesting” part about their smarts, however, is that they’re not as consistent as some of the crows have been found to be.

Heinrich, B.  1995.  An experimental investigation of insight in Common Ravens (Corvus corax).  Auk 112:  994-1003.

Bernd Heinrich (who wrote that paper) is famous (in the bird world) for his work on ravens.  He published a book called, “Ravens in Winter” that chronicles his work on the feeding behaviors of groups of these birds throughout the year.  In so many ways, they’re fascinating birds.  In this paper, though, the interesting part is that he set up problems for the birds to solve in order to get food.  A “smart” bird is one that could use its own experience via trial and error to find a way to gain access to a food source.  What Heinrich found was that some birds were able to solve the complex problems on their first try.  With no experience, they could perform all the necessary steps that were required to be completed to access a food source.  Other birds could not pick up those steps at all.  His paper shows two things:  1.  There’s variation in their abilities- not all ravens are the same;  and 2.  Some of them can create solutions to novel problems without having had any previous experience- insight.

Other examples of the problem-solving capacities of these birds come from some thorny issues in California.  Common Ravens are native to Southern California and have been particularly good at increasing their numbers around towns and cities as they’re growing.  Ravens are good opportunists.  They take advantage of the food that people provide for them (i.e. garbage and small pets).  The deserts of California contain another species, too (ok!  The deserts actually contain a lot of species):  the Desert Tortoise.  This tortoise is a federally endangered species, but the ravens aren’t aware of that fact.

Kristan, W.B. III and W.I. Boarman.  2003.  Spatial pattern of risk of Common Raven predation on Desert Tortoises.  Ecology 84:  2432-2443. 

Boarman, W.I.  1992.  Problems with management of a native predator on a threatened species:  Raven predation on Desert Tortoises.  Proceedings of the Fifteenth Vertebrate Pest Conference

Tortoises are notoriously tough to eat.  They have a thick shell and they can be quite heavy.  Common Ravens have a way around these issues.  They will go for younger tortoises, pick them up, fly up into the air and drop the tortoises on the ground to crack open their shells.  It’s a pretty ingenious way to access a tough-to-eat food source.  Smart birds (and maybe a little bit morbid).  Of course, the tortoises tend to be less impressed by the ravens’ foraging techniques.

Clearly, Poe chose his bird well.

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About thomasbiology

I'm an Associate Professor of Biology at Queens University of Charlotte with a background in animal behavior with an emphasis in bird song. I've got two secret goals with this blog (well, since I'm sharing them, they're not so secret): 1. To encourage people to look at the natural world around them- not just as a hiking destination, but to notice all the little things moving around them all the time; and 2. To show some of the science that relates to these little things moving around. There's some really fascinating research out there that so few people get to see.
This entry was posted in birds, conservation, ecology, foraging, predation, reptiles. Bookmark the permalink.

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