Category Archives: Archosaurs

Gannets, tough heads, and offshore oil drilling.

On a beach on the Isle of Palms, South Carolina:

gannet wing

…an immature Northern Gannet, washed ashore after a sea burial. Cause of death unknown. This bird’s brown plumage identifies it as a first-year bird, hatched this spring. Adults are white (seen here in my visit to a gannet colony in Scotland); second- and third-year birds are white splashed with brown.

North America hosts only six breeding colonies, all in Canada (three in the Gulf of St. Lawrence and three in coastal Newfoundland). Adults and youngsters alike head to southern waters for the winter, feeding offshore before returning to their rocky breeding sites in April. Overwinter survival for adults is often higher than 90%, but young birds have a harder time.

Gannets are plunge-divers, folding their wings and arrowing into the water, head-first. They use the momentum of the dive to swoop into schools of fish. If they miss on the first strike, they oar the water with their wings as they twist through the water after prey. Their bodies are well adapted to this punchy way of getting lunch. Air pockets and strong shoulder bones cushion the body. The conical head and chest offer little resistance to the flow of water or air. A study of Cape gannets found that they pierced the ocean’s skin like needles, barely decelerating as they hit. The beak has no nostrils, just a tiny slit that closes tight when water pushes against it. Gannet eyes are directed forward in a binocular gaze, protected by a movable transparent membrane. One tenth of a second after immersion, gannet eye lenses compensate for the changed refraction of light and snap into underwater mode.

North American gannets comprise about one quarter of the world population. The rest breed in Northern Europe and winter off the coast of Africa. After many decades of over-hunting and disturbance, American colonies have lately been growing. Aerial surveys of nesting sites indicate a annual increase of 4.4% from 1984 to 2009. After the Deepwater Horizon disaster, though, some breeding populations dipped. After the spill, gannets were the third most common bird species recovered (dead, sick, or oiled) by rescuers. Because the explosion and spill happened in late April, most adult gannets had left the Gulf. Immature birds lingered and were caught.

Now, the Atlantic waters off the southeastern coast are slated to be opened for drilling, despite opposition from the many human residents of the coast whose interests coincide with those of seabirds.

Photo and bird-finding credits: Katie Lehman and Eva Miller.

Turkey carving and muscle physiology. Prepare your dissection equipment, please.

Thanksgiving week promises many things, foremost among these delights are the physiology lessons offered by turkey carving.

The bird is presented to the world belly upward, as if in a dissecting dish. The carving knife scalpel slides through the skin, crossing feather tracts still visible as goose (really?) bumps, and cleaves a slice of pectoralis muscle. Who wants light meat? Then, after more blade-work, the femurs are dissociated from the pelvic girdle. Dark meat for anyone?

So many questions on one serving platter. Why the difference in color and taste? Are all birds this way? If we were to throttle then roast that insufferable Thanksgiving guest, would we have the same choice of meat cuts for our plates?

Turkeys are walkers. They fly only in short, plosive bursts. A startled turkey is a trebuchet of feathers. It twangs from the forest floor before smashing into the trees’ ramparts. The projectile moves fast — as much a forty miles per hour, I’m told — but has no staying power. Such bursts of power are delivered by “fast-twitch” muscle fibers that excel in anaerobic bursts, but then sag into exhaustion. Such muscles need relatively little oxygen and so their meat, when cooked, has none of the stain of blood or blood vessels.

Muscles in the legs are aerobic. They squeeze and pump all day without tiring. Such continual low-intensity activity requires “slow twitch” muscle fibers that are amply supplied with blood, capillaries, mitochondria, and oxygen-holding myoglobin. Under the knife: dark meat.

Turkeys are avian curiosities, though. Most other bird species use their wings for sustained flight and their legs for occasional strutting. In these species, therefore, the locations of dark and light meat are the reverse of the turkeys’ arrangement. A chickadee Thanksgiving would be instructive, although the meal would be short. From the roastlings’ chests we could carve slices of dark flight muscle, from the legs, the whiter meat.

As the breeders of industrial monstrosities know, most Americans prefer light meat to dark. By picking out the birds with the thickest and widest chest muscles, poultry scientists have bred varieties that by conforming to the desires of shoppers have lost the ability to grow to full adulthood without leg, lung, and wing problems. A pardoned turkey is not necessarily a lucky turkey.

And for that special Thanksgiving guest, the one whose boorishness or political rants add a spice of loathing to the table, remember that humans, too, have fast and slow twitch muscle fibers. Mostly, our muscles comprise a mix of the two, but the lower back and calf muscles are like turkey legs, always in use and so very dark. When the conversation reaches its nadir, such knowledge can provide a self-protective glaze of therapeutic imaginings.

Moon rising over an industrial park in Winchester, Tennessee.

starlings moon

Starlings: Come close, but stay away. The urge to flock, arrested at the last moment by beaks’ roving jabs, wings’ need to stretch.

Birded wires braided hundreds of meters of roadside. Within thirty minutes, the sun was down. The moon shed the season’s first frost onto metal, feather, and trash-strewn verge.

 

 

Flocks of locally-grown red junglefowl arrive in McClurg Hall

Thanks to the work of University of the South Executive Chef Rick Wright, along with his colleagues, local foods are gracing our dining hall. This year, the University will use about 20% of the food-purchasing budget in the local farm economy, a flow of $300,000. A few years ago, that number was zero. Next year, we’re on track for 30%.

This Sunday, fried chicken, along with squash from the University farm, was on the menu, a celebration of the fall harvest. Thank you Chef Rick Wright, Farm Manager Carolyn Hoagland, and the many staff, students, and administrators whose work is reorienting campus dining away from the outlet pipe of the industrial food system and toward Tennessee’s fields.

2015-11-08 chicken 007 2015-11-08 chicken 010 2015-11-08 chicken 011

Light, sound, hummingbird wings

From the dawn-light series (see also silk and moth wings)…

There is a moment in the early morning when the sun catpaws through the forest’s tangled blankets, illuminating my hummingbird feeder. The touch is gentle. The claws of midday are withheld. For two or three minutes, sun fires the blur of wings. For the rest of the day, the lights are off and wings move in gray-green, almost invisible.

hummer0hummer1hummer4Unlike other birds that power their flight with only the downstroke of the wing, hummingbirds flip their wings after the downstroke and generate more lift as they pull back their arms. The feather tips therefore scribe a figure-of-eight as the bird crams more gravity-fight into each back-and-forth. They do this fifty or more times every second. Humans can perceive only ten “images” per second and most movies are shot at twenty-four frames per second. To get an acoustic sense of the birds’ frenzy, I slowed a sound recording of the hummingbird in the photograph by one hundred times. The heart-beat thuds are the slowed wings, the strange wind is the sound of insects singing in techno-molasses:

(email subscribers, click on the header link to get to the sound file)

 

Silhouette: a short hawk quiz

A fuss of blue jays and robins. Look up:

hawkhawk2

Some clues:
unhappy songbirds
a tail that extends beyond the wing tips, but not too far
stout chest

Red-shouldered hawk. Not a Cooper’s Hawk? The tail is too short and the body too chunky. (Birders: let loose with corrections as needed!)

I used the computer to zip down the brightness of the photograph:

hawk3Coarse streaking: an immature bird. It took off after a young robin… and so the next generation relearn the old ways.

Bass Rock gannets

A view from the bull’s eye of the target, right before the release of a uric acid/digested fish bomb. The splattering impact is impressive. The smell lingers.

gannet1170,000 gannets (with 75,259 nests) make their summer homes on the Bass Rock, just off the Scottish coast.

Like Arthur’s Seat in Edinburgh, the Bass Rock is a volcanic plug, an erosion-resistant intrusion into softer rocks, now standing exposed. The Rock’s lighthouse was built by the family of Robert Louis Stevenson, as were many of Scotland’s nineteenth century lighthouses. Before the lighthouse, the Rock served variously over the centuries as a castle, prison, and hermitage. Now, birds have run of the place.

bass rockgannet2 Gannets are plunge-feeders, diving with wings folded onto their prey (cam-on-human video here; cam-on-bird video here, the green is marking paint on the bird’s feathers).

Gannets fly up to 100 km from the colony in search of food. Unlike most other northern seabirds, gannet populations have grown lately, perhaps because the birds are no longer hunted for meat and eggs (except for a small hunt on the Outer Hebrides). The fishing industry leaves plenty of edible “by-catch” and removes larger fish that would compete with gannets for food.

Nests are perched on every available rock ledge. A seaweed base and rim gives the eggs and nestlings a suitably salty start to life, spiced with plastic flotsam.

gannet3