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Birds – Variety and Extremes

By Dan Greaney on September 28, 2019 in BirdWords

Somali Ostrich

The ten thousand species of birds in the world come with tremendous variety. The ostrich can stand nine feet tall, tip the scales at 280 pounds, and run at over forty miles per hour. The bee hummingbird is less than two and a half inches long, weighs one twentieth of an ounce, and can’t run at all, or even walk.

Bee Hummingbird

A red-breasted merganser flew even with a plane at an air speed of over 80 mph, ground speed over a hundred. Peregrine falcons stooping on prey have sped to at least 186 mph. Hummingbirds can hover in place, a flight achievement of zero mph.

The engine of a plane in Africa sucked in a Ruppell’s griffon vulture–at an altitude of 36,100 feet! Penguins “fly” only under water. New Zealand’s kiwi has stubby little wings, perhaps as useful as a T-rex’s hands; it cannot fly.

Killdeer nest in open flats, maybe gathering just a couple pebbles to mark the site. Orioles weave hanging baskets of plant fiber or other debris. Cliff swallows build with mud, swiftlets use saliva, and hummingbirds gather and form lichen and spider webs. Kingfishers nest in tunnels they dig, as much as eight feet into the ground. Emperor penguins’ feet serve as nests. Eagles build with sticks, adding more as they re-use the nest over years and generations; a nest in Florida was 9.5 feet across, 20 feet deep, and estimated to weigh over two tons. Gyrfalcons in Greenland use a cliff nest that is 2500 years old.

Chimney Swift on Nest

Osprey flap over water looking for fish to catch. The thick-billed murre has been found swimming 690 feet under water.

Goatsuckers and owls wear camouflage feathers that blend into the gray-brown bark they press against. Tanagers, orioles, and honeycreepers blaze brilliant colors with stunning richness and iridescence.

Western Screech-Owl

All this variety of behavior and physical features is the result of the distinctive habitats that grace our planet. The diverse opportunities, requirements, and happenstance of survival hone the qualities of plumage, flight, size, color, and nest building, as well as the shape and strength of feet and bills, flocking behavior, and everything else about the birds.

The thing about these adaptations is that they do not just permit living a certain way in a certain habitat; they require it. An eagle can’t catch flies from the air to have its dinner. A woodpecker can’t paddle like a duck and skim algae off the water. Like all living things, birds need the habitat they are designed for.

Amazon Fires

But now the world is changing. The Amazon is burning, the ice caps are melting, and the reefs are dying. What are the birds to do?

Many have begun the spiral toward extinction. Depending on how fast and how extremely the changes come, some will adapt, as they always have on the changing Earth.

The uneven pattern of evolution is normal. The biologist Stephen Jay Gould termed it punctuated equilibrium, long periods of relative stability “punctuated” by brief periods of rapid evolutionary change.

Generally speaking, when change comes fast, creatures with short generations do well. Bacteria, for instance, can “grow up” and reproduce–which in their case means divide in two–in as little as twenty minutes. The quick regeneration allows for more mutation and more rapid genetic development of adaptations to the new environment. We humans reproduce more slowly, so don’t do well by this measure. However, we are capable of considerable non-biological adaptation–say, build and operate an AC unit.

As for birds? So much depends.

Swift and Secret

By Dan Greaney on June 29, 2019 in BirdWords

Black Swift

Black swifts are birds of mystery. We know they’re fast, probably powering to over 100 mph. We know they’re fliers, apparently spending up to ten months a year in flight. But much that is known or speculated about them is based on only a few observations, so uncertainty is also part of our understanding.

Black Swift at Burney Falls photo courtesy Glen Tepke

Like the Redding eagles, black swifts seem comfortable, or at least unconcerned, with having people around; but unlike the eagles, their “around” doesn’t include downtown. They do their living in out-of-the-way places, and even there they are unobtrusive neighbors. They nest in dark crevices of waterfall or oceanside cliffs; they forage high above us, and never perch on wires or trees where we can see them; and they utterly neglect to announce themselves with colorful displays or loud songs. They are small, black-brown birds that flit by with the speed of their name, and their light chittering song is often lost to our ears in the roar of nearby water. They are variously reported as having stable local populations and as having declined 94% over the last fifty years.

Burney Falls

But here in the North State they give us this much: they nest at Burney Falls. Each spring, for longer than our history can testify, black swifts make their way to the torrent, where they build and repair nests in the protected nooks among braids of tumbling water. Working with mud and moss, they fashion a hand-sized crib, palm up to cradle their single egg. In the soggy damp of the falls, the egg will take four weeks to hatch, twice as long as most birds their size. Then, with continuing slow development, the chick will not fledge for another month and a half.

Black Swift on Nest photo courtesy of Julie Price

It is at nest-sites that we can best observe these wide-ranging birds. Both parents incubate and tend the young. There are reports of adults roosting near the nest while their mates warm the baby. But those are the only documented reports of these birds landing at all.

Swifts are in the family Apodidae, meaning those without feet. In fact, their feet and legs are reduced, capable of catching cliffside toeholds, but incapable of standing, perching upright, or walking. It is said that if they ever landed on the ground they would not be able to take off again. They go into flight by dropping from their cliff-hold.

Black Swifts at Burney Falls photo courtesy Glen Tepke

Once airborne, however, they are in their element. They zip through the air, often in loose flocks, catching and eating insects on the wing, often higher up than we can see them. They drink water by skimming open-billed at the surface of a lake or pool. They apparently mate on the wing, and almost certainly sleep in the air. Studies on oceanic frigatebirds show that some birds can sleep one hemisphere of the brain at a time–a sleep schedule that seems unappealing, but beats staying awake for ten months!

When young black swifts fledge, they have no trial flights. Most songbird fledglings flutter weakly and hide and rest, gradually building their flight muscles. But swifts are immediately on their way, catching insects and winging–where?

They will fledge in July. By September they are out of Shasta County. By mid-October they are out of the country. Until 2012 we could only guess where they went. That year researchers using ultra-light geolocators studied black swifts from Colorado. They learned that those swifts winter in the lowland rainforest of western Brazil, a land rich in vegetation and the flying insects these birds need.

Maybe our Burney Falls black swifts winter there, too. But we don’t know. They haven’t told us yet.

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