Tag Archives: skeletons

Avian flight I: built for flight

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Laughing Gulls in flight

Laughing Gulls in flight

Everything about avian morphology has been shaped by the requirements of flight. Flight is hard. Animals are heavy, being largely composed of water, and air is not dense; you have to work hard to generate any force by manipulating air. The problem for any flying animal is to be light yet powerful – and to still be a viable animal, capable of eating and storing energy and making babies. A hypothetical weak but extremely light animal – think an air-jellyfish – might be able to fly, but would probably starve. While the ocean is filled with floating particles that real jellyfish can catch simply by passively floating, the air is not so bountiful. (You could argue that web spiders filter-feed in air, but… all right, I don’t know if air-jellyfish are impossible. I think we’re getting off-topic here.)

Air-jellyfish floating in a pink sunset.(Or, Northeast Pacific sea nettle in an artistically-lit tank at the Shedd Aquarium.)

Air-jellyfish wafting through a pink sunset.
(Or, Northeast Pacific sea nettle in an artistically-lit tank at the Shedd Aquarium.)

In any case, birds didn’t start out as light, thin, filmy creatures. They started out as small raptor-y dinosaurs. Natural selection acts only on the traits that are present: massive change to the shape of an organism is hard. (Not impossible! But comparatively rarer.) Birds started out with backbones, four limbs, a head, two eyes, etc., and they evolved flight from that initial morphology.

But how do you make a dinosaur that can fly? Dinosaurs are strong, yes, but they are heavy. Bones are heavy; muscle is heavy; fat is heavy; teeth are heavy.

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White gloves, strange rooms

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One of the things I like about what I do is the strangeness of my everyday situations. There’s more of the boring old Sitting At A Computer Situation than I would like, but the Measuring Baby Birds On A Mountaintop Situation helps make up for that.

Now that field work is (mostly) over for the season, my situations are different, but not really less strange.

Strange Room #1

In order to look at the genetics of the juncos, I’ve been doing lab work in the Museum’s Evolutionary Genetics Lab. Lab work was my introduction to ornithology as an undergrad, and I’ve always liked it, despite the bleach and the potentially-toxic chemicals and the way my nose always itches and I can’t scratch it because I’ve got latex gloves on. The colors, noises, and vocabulary of lab work are specialized and surreal: the stacks of plastic racks in bright red, yellow, blue; the whirr of centrifuges starting up, like tiny revving plane engines; aliquot, vortex, elution buffer. I like the contrariness of refrigerators and microwaves with NO FOOD scolded across them. The concentration required to pipette the right amounts of the right reagents into the right tubes again and again and again makes it a kind of meditation.

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