The Bone-Eaters

It’s ironic that the so-called Father of Tragedy was killed by so comical device as a falling turtle. Aeschylus, author of the Oresteia cycle and one of the original masters of Greek theatre, was said to have died of a traumatic brain injury when an eagle mistook his bald head for a rock and dropped a turtle on it. Is that comedy, or is that tragedy? One day, you’re creating the artistic devices which will influence all of Western theatre, cinema, and literature for millenia to come; the next day, Bam! Turtle to the head.

Either way, it is an ignoble and contrived death for a playwright; too hasty, random, deus ex machina. And if the story is true, it was probably not anything even so noble as an eagle that dropped the fatal turtle, but a Lammergeier, or Bearded Vulture. Dropping turtles on rocks is a special trick peculiar to this magnificent bird, whose wingspan can reach 9 feet in diameter. But turtles are only a side dish to the Lammergeier’s main staple, which is bone marrow. If you are laying around today still digesting Thanksgiving dinner, imagine what it would be like if, instead of turkey, you were digesting pure bone.

In the Old World, in places where vast forests don’t hide the dead, vultures have evolved to eat primarily large carcasses. A water buffalo rotting in the Tanzanian sun will feed a whole flock of Gryphon vultures, whose raspy tongues will leave its bones licked clean as if preserved for mounting in a museum. But Nature abhors waste, and there is yet nutrition in a skeleton. Enter the patient Lammergeier, the vulture of vultures. Though only 15 lbs, it is large enough to pick up an 8 lb. water buffalo femur and carry it on thermal updrafts. When it is high enough, it will drop the bone on a large, flat rock — it usually has a favorite cluster of rocks, called an ossuary — hoping to shatter it and get to the marrow. It is a difficult skill to master, taking up to seven years for young birds to learn, but it is worth the practice. Marrow is an incredibly rich source of protein and nutrients, and a Lammergeier can expect to be as well-fed from the marrow in a skeleton as it would if it were sitting down to the meat from the carcass. But the Lammergeier has no special tools for extracting the marrow, it also has to eat the bone shards to which the marrow clings.

Bone is an extremely indigestible material, being essentially an organic limestone, calcium hydroxyapatite. If you were to eat large bone shards, you’d probably tear your intestinal lining before you extracted much of its nutriment. Very few animals eat bone because few animals have any reason to. Almost alone in the animal kingdom, the Osedax polychaetes, or boneworms, digest the bones of whales that have fallen into the abyss — a phenomenon rare enough to warrant its own term, “whalefall” — scraping out whatever fats they can from between the ossicles; like writhing flowers in long planting boxes, there are gardens of these in the graveyards of the deep. Hyenas will eat bone, but it doesn’t make up a significant part of their diet. Lammergeiers, on the other hand, have a diet that is 90% bone; they will even eat owl pellets, which contain the swallowed bones an owl couldn’t digest. Lammergeiers have solved the problem of bone digestibility by creating incredibly caustic gastric acid. Human gastric acid remains between pH 1 and pH 1.5, while a Lammergeier’s stomach registers around pH 0.7, making it close to pure hydrochloric acid. Add to that an extra-long intestinal tract and a lifestyle of effortless gliding, and you can see how the birds make a living out of eating bone. To get to the rarest and most succulent meat on the cow, a Lammergeier has a stomach that can dissolve almost anything.

Vultures are peaceable sorts of birds, and Lammergeiers are the most peaceable, as they rarely squabble while eating. After all, getting their food is a matter of skill, not speed. They will tussle for mates, as many animals do, but rarely fight over meals; theirs is a meditative ritual of flying, dropping, breaking. A Lammergeier might drop the same bone twenty times before it falls at just the right angle to crack it. It is hard and lonely work. But only once the Lammergeier has broken its bones — expertly, gracefully, with much concentration — is an animal truly and completely gone. This great kite of a bird is the last stop before oblivion: before it, there are still parts of you in the food web; after it, all that is left is mineral. You’re not truly gone before there’s nothing left of you to use. Nature always licks its plate clean, often right off the fine china.


About quantumbiologist

Christian Drake, AKA The Quantum Biologist, is a naturalist and poet formerly of Albuquerque, NM and currently living deep in the backwoods of the Connecticut Berkshires. He has worked in aquariums and planetariums, national parks and urban forests. When not birding or turning over rocks to find weird bugs, he enjoys rockabilly music, gourmet cooking, playing harmonica and writing dirty haiku. View all posts by quantumbiologist

8 responses to “The Bone-Eaters

  • Copernicus

    Well, a golden eagle will eat lammergeier vomit. Not that lammergeiers have eating disorders; it’s a reaction that understandably helps vultures achieve liftoff quickly when attacked. If I recall, several eagles regard the molecular reorganization performed by vulture stomachs as something as a favor. Kind of the way people actually purchase mcnuggets or liverwurst.

    But if the lammergeier is the last upward draft of an organism’s transit to the ether, then the eagle’s dining habits have to fill some further, meta role in that transubstantiation.

    • quantumbiologist

      That is crazy awesome. Conceivably, a mouse eaten by an owl could have its hair and bones coughed up and eaten by a lammergeier, which in turn regurgitates it to be eaten by a golden eagle. That mouse just passed into the digestive tracts of three different species of raptor. What a way to go.

      Marrow being as nutritious as it is, it’s not surprising that another animal would want to steal it once it’s been rendered digestible. Birds don’t really have a problem eating each other’s vomit; they’ve been doing it since they hatched. As for the golden eagle finishing off what the lammergeier started, I have no idea what bizarre niche in the circle of life that would fill.

  • Rebecca

    Boneworms actually popped up on a recent episode of the TV show Bones – they were eating a human skeleton that had been on the ocean floor for some time.

    • quantumbiologist

      I could, and probably should, do an entire post about boneworms, otherwise known as zombie worms, otherwise known as bone-eating snot-flowers. There are entire species which live nowhere but whalefalls, which in themselves are incredibly rare and usually spaced incredibly far apart.

      As for the TV show, I’ve never seen it, but I kind of imagine that everything that has ever been related to bones has been on that show. Doesn’t seem like you could do infinite things with that concept.

  • Kat Sanford

    So interesting to me that it’s called an ossuary, since an ossuary is a receptacle for bones.

    One of the things on my life list is to go to Sedlec Ossuary in the Czech Republic. Otherwise known as the church of bones.

    Something tells me you’d like it.

  • Copernicus

    Southern breeding range… it’s an area of high mesas like AZ or NM.

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