Of Flying Birds and Cold Dinosaurs

May 12, 2017 | Posted in: Modern Bestiary

Mosque swallow, Ibis (quarterly journal of the British Ornithologists Union), Vol. IV, 1862.

Mosque swallow, Ibis (quarterly journal of the British Ornithologists Union), Vol. IV, 1862, courtesy of the Biodiversity Heritage Library.

“The heart and soul of a bird is summed up in a feather: a feather defines what a bird is, and is the essence of what a bird does. Which is fly.” Simon Barnes, Ten Million Aliens

 

It’s been about a month since the barn swallows have returned. For half of each year they migrate down to South America to winter on the balmy side of the equator. And with each spring they return to my town to nest under the roofs and ledges of buildings, and with the start of May they’re first hatchlings are hatching. Several pairs nest at the entrance of a building across from my home, so each morning and evening I get to watch their aerial performance. And oh, they make flight look effortlessly decadent, all swoops and high speed turns, sheer agility, swiftness, and glee.

But for all the appearance of ease, flight is indeed decadent, a most expensive lifestyle. Fighting gravity with each takeoff and accelerating through space with bursts of speed are metabolic drainers, and all the short flights favored by many smaller birds cost a great deal more than the gliding adopted by larger birds and perfected by the albatross.

But how did flight come about anyhow? Did ancient reptiles, like us, look up into the great big blue yonder and dream of soaring? No, nothing so poetic, but rather something very practical led to flight:

“We have 10,000-plus species of birds on this planet, living their own lives and illuminating human ones, and almost all of them doing both by means of their ability to fly—and it all came about as a bi-product of the fact that dinosaurs felt the cold. Some species of dinosaurs evolved feathers for thermoregulation: an example being Dilong paradoxus, related to Tyrannosaurus rex but living 60-odd million years earlier. They weren’t fliers, they weren’t even half-and-halfers attempting to fly. For them, feathers were nothing to do with flight. They were theropod dinosaurs and their experiments in insulation filled the air with birds.” Barnes

Faune de la Sénégambie, T.1 Atlas (1883-1885), A.T. de Rochebrune, Biodiversity Heritage Library.

Illustration from Faune de la Sénégambie, T.1 Atlas (1883-1885), A.T. de Rochebrune, courtesy of the Biodiversity Heritage Library.

Yes, some dinosaurs were cold, so they grew a feathery coat and whether through jumping or falling, uncovered the gravity-defying uses of these light, yet oh-so-strong, stiff, yet oh-so-flexible appendages. And voila, millions upon millions of years later, you have dinosaurs still alive in the flashy, flying guise of birds. What a feat of evolution this transformation was:

“Reptilian arms became wings, the breastbone became a keel, to which the big muscles for flapping are attached. The body is power by a mighty four-chambered heart. Birds have a breathing system that is far more efficient than the in-out method we mammals use: one in which hollow bones and air sacs are constantly used to flush out stale air. Flight is highly expensive in terms of energy: the birds’ breathing system gives them a constant supply of the freshest possible air.” Barnes

These amazing feathered bodies, so light and yet capable of feats of strength and skill beyond our full understanding, also seem to house such gusto for life. Birds sing and fly with undeniable pleasure and even their territorial disputes have such a flair and frenzy that it almost seems theatrical, as if birds know that all the world’s a stage for them. Their brains have grown along with their feathers and hearts (greatly outpacing reptiles) and some species rank alongside mammals for documented intelligence. They also raise their young as we mammals do (and as reptiles don’t), teaching them language along with survival. Such a long evolutionary trip it’s been for birds, and it’s all thanks to some cold-sensitive dinosaurs.

Sparrows Flying, Watanabe Seitei (1851-1918).

Sparrows Flying, Watanabe Seitei (1851-1918).

“[T]he miraculous nature of every bird that retains flight: the high energy demands of that lifestyle clearly put every flying bird on the far edge of evolutionary possibilities. Every sparrow is a small miracle.” Barnes

Just one person out of 7 billion + on a journey to live a life that is vibrant, soul-fulfilling, useful to others, and consciously engaged with the ecological community that sustains all life, including mine and yours.