Ravens: practicing monogamy for now

Photo credit: Peter Wallack

Photo credit: Peter Wallack

Valentine’s Day has come and gone again…the day set aside for showering that special someone in your life with love, gifts, affection and maybe even an engagement ring. The first step in making the ultimate promise to spend the rest of your life with the person you love or “until death do us part” as the marriage vows conclude.

The notion of monogamy exists in other realms of the animal kingdom, including the raven. Yes, that large black, sleek, almost regal bird supposedly mates for life.

According to the Smithsonian Handbooks Birds of North America Western Region, Corvus corax, better known as the common raven, is the largest bird in the scientific order Passeriformes (perching birds), which includes more than half of all bird species. Ravens are members of the family Corvidae, the scientific name for the closely related group of birds that also includes crows and jays.

Ravens and crows look very similar and are hard to tell apart, but ravens are much larger reaching 26 inches in length with a wingspan up to 4.5 feet, close to twice the size of crows. This places ravens in the same league as hawks and falcons, not to mention the raven’s ability to compete with these famous fliers in aerial stunts and acrobatics.

Another special trait distinguishing ravens from crows is a raven’s shaggy throat feathers. While these feathers aren’t always obvious, in some instances the throat feathers stick out giving ravens the look of having an unruly black mane around their neck. And one last trait to help distinguish ravens from crows is their calls. Crows have the super loud somewhat annoying calls, caw-cawing all over the place, while ravens employ a great variety of calls including a raspy trill or more defined yelp.

Genetic studies done by scientists with the U.S. Geological Survey have found our California ravens to be special. After running tests on 72 genetic samples from ravens across the northern hemisphere they found two genetic groups: California ravens and everyone else, which scientists refer to as the California clade and the Holarctic clade. While all common ravens look the same, ravens in the Midwest and Northeast have more genetically in common with ravens in Asia and Europe than ravens in California.

Ravens are adept hunters, but their diverse diet has given these birds a bad rap wherever they are found. Sharing a vulture’s taste for dead and decaying meat, ravens have been associated with death and dying. Sometimes the skin of dead animals is too tough for a raven’s beak to break through and they wait for other predators to rip in before helping themselves. But why wait on death as a food source when you can also eat garbage?

Yes, ravens also enjoy eating garbage and follow the human trash trail wherever it leads. Their diverse diet has gotten them into trouble too. According to the Birds of North America database, their penchant for “pecking eyes from newborn lambs” has caused some people to label them a pest.

Ravens also possess some odd habits that have further solidified their pest status. The Birds of North America database cites their aggravating tendency to “peel identification labels off toxic waste drums.” And studies done by the U.S. Geological Survey show that ravens have a fondness for pecking through desert tortoise shells. Just to clarify, these aren’t egg shells, but the actual shell a tortoise carries on its back. This is causing major problems in efforts to help the desert tortoise recover in California. Another human-induced problem caused by trash left in desert areas allowing ravens to flourish in great numbers.

These strange behaviors may cause some to question a raven’s intelligence, but they are still considered to be crafty, cunning and clever. Dr. Bernd Heinrich, an expert on ravens and also the author of the books Mind of the Raven and Ravens in Winter, has performed experiments with juvenile ravens to test their intelligence.

In one problem-solving test, “hand-reared ravens were confronted with meat dangled from a .7 meter [2.2 feet] string.” As the tantalizing meat hung from their perch, some of the ravens quickly figured out how to get it “by pulling the string up…then successively reaching down, pulling the string up, stepping on the pulled-up loop of string, reaching down again until the meat was grasped.” This is taken from the article in the Birds of North America database that happens to be co-authored by the very same Dr. Bernd Heinrich.

So I felt compelled to contact Dr. Heinrich and ask him about this business of ravens allegedly mating for life. Do these carrion eating, test-passing, acrobatic flying birds really practice monogamy?

And suddenly I found myself in a philosophical debate about monogamy. He emailed back asking me, “First, what do YOU mean by monogamy? After you give me your definition I will try to answer.”

I have to admit I had to think about this for a bit, but wrote back that to me it means “mating and living with the same person for life.” Or as the marriage vows proclaim “until death do us part.” After I sent my response I thought, what is the real definition of monogamy? According to The New Shorter Oxford English Dictionary, monogamy means: “The condition, rule, or custom of being married to only one person at a time. The habit of animals, especially birds, of living in pairs, or having only one mate.”

Suddenly my definition of monogamy seemed conservative with my life-long pledge and death separation requirements.

Dr. Heinrich wrote back explaining that while more than 90 percent of birds are classified as monogamous there are many qualifiers and as “for life” probably none make the list. He explained that “the biggest qualifier is ‘serial,’ meaning monogamous in a given relationship, but could have a new mate during the next reproductive cycle.”

He said that, “Many insects are truly monogamists—they don’t need to mate more than once and don’t live long; a mayfly hatches out, mates and dies.” So mayflies and insects like them may be the only practitioners of a strict definition of monogamy. With only one chance at mating before death they practice monogamy by default.

But Dr. Heinrich also explained that, “ravens are more monogamous than many, in the sense that the same pair may stay together for years. I have had mated pairs, and seen how they are totally uninterested in other individuals, even when a mate is not available.”

Since ravens live for more than half a century, Heinrich said that “nobody on earth has demonstrated that there was no extra-pair copulation.” And he said that in almost all the genetic investigations to check paternity of chicks of “monogamous” bird species there is quite a bit of extra-pair fertilization. “But I suspect in ravens it would be rare,” he concludes.

So there you have it, ravens seem to be able to stay true to the one they have for now…not necessarily for life. This seems like a good philosophy to follow, practice monogamy with the one you love now and you probably have a much higher chance of celebrating Valentine’s Day with that same special someone next year.

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