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An Avian Santa Claus

By on January 3, 2023 in BirdWords

Pileated Woodpecker Female

Santa Claus isn’t the only one in a pointy red cap who flies around in winter handing out presents. Pileated woodpeckers do, too. As a matter of fact, they fly year round, delivering gifts through large swaths of North American forests, mostly south of the reindeer.

Pileated woodpeckers thrive among big trees. They prosper in west coast conifers and arc across Canada into deciduous forests throughout the eastern US. Among the big trees, they build and deliver their gifts as only these largest woodpeckers in North America can.

Their gifts are staples of life–food and shelter. Their tools for delivering them are those of carpentry, or maybe jack-hammering–tools of woodpeckers generally, but writ large in these crow-sized birds.

First they need a firm foundation for their hammering. The three toes forward and one back that most birds have would be comparatively unstable. Woodpeckers instead have on each foot two toes forward and two back. This allows a solid grip at the variety of angles at which woodpeckers work.

Further, woodpeckers have stiff tails that function with their feet to create a sturdy tripod from which to work.

Well anchored, woodpeckers still need a stout, strong bill to pound and pry. These birds regularly punch wood at about fifteen miles per hour. With what are probably the continent’s most heavy-duty natural chisels, pileated woodpeckers excavate gaping holes in dead trees. However, the abrupt deceleration of smacking their heads into solid wood creates impacts up to fifteen times what humans can sustain–impacts that would shut down the NFL with concussion injuries. All their concussive pounding requires some protection for these bird brains. Fortunately, they have it.

Human hyoid bones, which anchor our tongues, are firmly based at the top of our throats. Woodpecker hyoid bones are anchored at the base of their upper bill and flex in two bands over and around the brain before curving up under it to root the tongue. This limber anatomy creates extra elastic length for the tongue, allowing woodpeckers to probe deeply after insects in their excavations. It also lets the hyoid bone act as a sort of seat belt around the brain, tightening against destructive sloshing inside the skull.

The hyoid can’t reduce the pounding to zero, however, and woodpeckers have another brain-protecting design. Their brains are oriented more vertically than ours. That spreads out the force of frontal impact over a larger area of the brain, effectively dissipating the blow of each whomp on wood.

With these tools for effective and sustainable wood-carving, the woodpeckers can make their gifts–presents not wrapped up with a bow but offering vitals to their forest neighborhoods.

The large, often rectangular feeding holes that pileated woodpeckers create expose their prime food, carpenter ants, to not just themselves but to wrens and other birds, too, a feast any time of year.

And their nesting cavities? The excavations of smaller woodpeckers often end up as homes for smaller birds–swallows, titmice, nuthatches, chickadees, bluebirds, etc. But pileated woodpecker cavities are super-sized, and can provide homes for bigger forest and woodland residents: numerous ducks–mergansers, buffleheads, and wood ducks; owls of various kinds; other woodpeckers that are upsizing; and many mammals, including squirrels, flying squirrels, different bat species, pine martens, and raccoons.

The efforts of pileated woodpeckers are a boon to the forests. Each year mated pairs select one of their many holes and there raise their brood of three to five young, ensuring that this avian Santa Claus keeps giving.

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Ravens – gotta love ‘em, but–

By on October 30, 2022 in BirdWords

Common Raven

Raven wings rake the air around the Northern Hemisphere, so it is not surprising that they are also tucked into an extensive array of human mythologies.

In Pacific Northwest traditions, the raven is the creator and, in what seems a wry pairing of roles, a trickster. For the Norse, two ravens scour the Earth each morning and provide to Odin the wisdom and knowledge they find. In China, ravens are credited with feeding their parents, and thus they symbolize filial gratitude and respect. Modern Londoners maintain an aviary of ravens at the Tower in respect to the legend that their loss would signal the end of the Empire. In the US, Edgar Allen Poe gave the raven the repeated knell of the finality of death’s parting, “Nevermore.”

Ravens are the planet’s largest songbird–loud, bold, and conspicuous. They are not, however, musical geniuses. Songbirds are defined by having a finely-muscled syrinx, a voice box that allows the variety and complexity of birdsong that humans enjoy around the world. With all that potential, ravens seem to have undersold themselves, settling on a range of croaks and clucks, generally burrier than the caws of crows, that support their communication but lack musicality as we understand it.

Music notwithstanding, avian scientists recognize ravens as among the most intelligent of birds. Like at least most of the warm-blooded world, ravens share in the social and biological intelligence that supports care for their young and getting along with one another. They are versatile, with the powerful bill and analytic capacity to adapt to new situations. Lab tests for some sorts of intelligence–mechanical and numerical–place them on par with chimpanzees and orangutans, roughly the level of human toddlers. Common observation shows another feature that indicates intelligence: ravens dive and roll through mountain airstreams for no apparent reason other than what in humans we call play.

If population is an adequate measure, ravens are highly successful. In this time when most songbirds are declining, their numbers are increasing. They are rather like us, drawing sustenance from beach to mountaintop, from desert to arctic, from trash piles to pristine wilderness.

Their triumphs, of course, come at a cost. Living things survive on other living things, and ravens are no exception to that rule. Patrolling highways through forests opened up by development, by burns and logging, and by the roads themselves, ravens dine not just on roadkill and human refuse, but also on the more exposed eggs and young of other birds, many of whom are already dwindling. Condors, despite their daunting size, have probably long suffered from the bolder and more clever ravens; beginning in the 1980’s era of condor conservation, officials found the need to haze and cull ravens to protect the larger birds’ nests. In the Arctic, whether warming is yet prompting increased raven predation on the world’s nesting shorebirds and ducks is something that research is still determining, but in 1913 camera technology allowed the first observation of a pair of ravens killing and subsequently feeding to their own nestlings a litter of four arctic fox pups.

A Conspiracy of Ravens

We don’t know how much ravens will impact other species in a warmer and less verdant world, but we do know that they are opportunistic predators. Fortunately, their harm to other species is individual, not systemic; raven proliferation is just one small facet of the broader harm posed by development and climate change. But we should recognize that ravens, for all their intelligence, operate with the short-sighted and self-centered adaptations that evolution writes for survival in a more stable world. We cannot expect them to curb their reproduction or their appetites. Intriguing as ravens are, each year a mated pair raises its handful of offspring and adds to the world its own version of a dubious “ever more.”

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Small Hawks Arriving for Winter

By on September 30, 2022 in BirdWords

Sharp-shinned Hawk

The raptors are coming, the raptors are coming!

Fall is upon us, and migration is in full swing.  The cliff swallows and orioles were moving in July, with warblers and vireos on their heels. Now, as their exodus southward continues, look for birds that have nested north of us to arrive. One of our winter residents, down from nesting in mountain conifers and Canada’s boreal forest, is the sharp-shinned hawk.

Raptors are birds of prey. Among the many North American raptors–eagles, hawks, falcons, etc.–the sharp-shinned is the smallest in the group called accipiters, stealth hunters that prey mainly on birds in fairly dense woods. They are well adapted to that habitat and lifestyle. Let’s start with their eyes.

Sharp-shinned Hawk Close

Sharp-shinned hawks, or “sharpies,” have the front-facing eyes typical of vertebrate predators. That positioning creates a blind spot behind, but allows two eyes to focus forward–the binocular vision that supports depth perception and successful hunting. Relative to our eyes, the hawks have about eight times as many rods and cones, providing their innate version of HD viewing. Further, where our eyes each have one fovea, or focal point, sharpie optical nerve endings are arranged to form two foveae–a central one that can focus on a fleeing bird and a peripheral one that can help the hawk avoid crashing into branches.

Forest hunting has also helped design sharpie body form. Their short, round wings sacrifice the soaring ability of larger hawks but gain mobility and quick acceleration for sudden attacks. Their long tails serve as rudders for abrupt maneuvering through forest obstacles.

One of the sharpie’s hunting styles is to perch low and explode upon an unsuspecting sparrow that happens by. If you see this small hawk perched, you may be able to observe its yellow, pencil-thin legs and fluffy white feathers under the base of the tail. Adults have red eyes, a slate-gray cap and back, gray-barred tail, and cinnamon-red barring on the breast. Juveniles have yellow eyes and are generally mottled brown, with thick streaks on the breast.

Sharp-Shinned Hawk in Flight courtesy Tom Murray

Sharpies also hunt by cruising low through brush and trees and, with sudden acceleration, pouncing on a potential meal. If you see this, it’s hard to discern more than a dark blur rushing by.

They hide their nests below the canopy in their forest homes, and tucked against a trunk. The female incubates her handful of eggs for a month. The male brings in food for the hatchlings, and later, the female, half again larger than the male, brings in larger prey to feed the growing chicks. The young will fledge at about a month old, and must develop their coordination and skills before striking out on their own and facing their first winter.

Sharpies are often seen at windy passes and peaks during migration. Perhaps their wings, so good for forest navigation but not for distance flying, benefit from the Earth’s corridors of air.

Through the winter they have no nests to hide and are less committed to being in forests. They can be found in suburbs and will frequently visit bird feeders, providing a twist on the definition of “bird feeding,” and generally stirring a mix of dismay and intrigue in their human neighbors.

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Bird With A Shiny Robe

By on August 27, 2022 in BirdWords

Phainopepla Male by David Bogener

Some birds just won’t do without a little pzzazz in their doing. Phainopeplas are among them, tip to tail.

They are slight birds, the length of a pencil, and nearly as much tail as anything else. But their eyes are cranberry red, and their heads sport flashy crests, erect feathers reminiscent of a Greek soldier’s helmet decor or a contemporary hairstyle.

And their feathers! Known as “silky flycatchers,” these birds paddle the air powerfully, but somehow retain a soft, fluttery quality to their wingbeats. In color, the females wear the gray-brown of nesting camouflage. Males, by contrast, wear glossy black, broken only by white wing patches that flash in flight. Their feathers earn the species its name. “Phainopepla” comes from the Greek for “shiny robe.”

Phainopepla Female by David Bogener

Despite their haute couture getup, the males are no slouches in domestic duties. They begin in winter, by selecting a nesting site, usually 10-20 feet up a tree in mistletoe. Then they dance in the air high above it, hoping to impress a female by fluttering, diving, and flashing their wing patches. They entice the females with ritual feeding of berries or insects. Once a pair forms, the male builds a tidy, palm-sized nest, woven together with spider silk and lined with hair or feathers. She may add some lining, and then lays 2-3 eggs.

The pair share two weeks of incubating duties, and typically do not leave the nest until replaced by a mate. After the eggs hatch, both parents care for the young through fledging at about three weeks old.

Like most songbirds, phainopeplas feed their children insects, providing a high protein diet that lets the young develop quickly. For themselves, however, they eat mostly berries, and mistletoe is a particular favorite. Although toxic to us, mistletoe berries pass through the phainopeplas’ digestive tracts quickly, imparting no poison but also little nutrition. The birds make up for the quality of the berries with quantity, eating up to 1100 mistletoe berries a day. In defecating those berries they help spread mistletoe to new growing sites.

Mistletoe

Food may or may not shape human culture, but it seems central to phainopepla society. Mistletoe clumps provide both food and nesting-site cover. Egg-laying appears to be timed with its berry-ripening. Where mistletoe is scarce, a pair will defend its mistletoe turf, chasing off other phainopeplas. Where mistletoe is abundant, many phainopeplas may nest colonially, sharing the resource and chasing off invaders such as bluebirds, which also eat mistletoe, and scrub-jays, which eat eggs and nestlings.

The guidebooks indicate that phainopeplas migrate south from their northernmost range, here in Shasta County, but they have been found in the area year-round. Mistletoe is abundant in the blue oak woodlands, and even outside breeding season makes a good place to find these birds. Look just above mistletoe clumps for a slender, upright phainopepla guarding its food source. A thriving population of the birds was recently observed south of the Redding Airport at Fairway Oaks Mobile Home Park and the adjoining Tucker Oaks Golf Course.

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Songster of the Conifers–beautiful but invisible?

By on July 31, 2022 in BirdWords
Red-breasted Nuthatch

Red-breasted Nuthatch

If you have entered the world of the conifers above the Central Valley, or throughout most of North America for that matter, you stand a good chance of having heard an ongoing, nasal ankh, ankh, ankh, ankh. It is the song of the red-breasted nuthatches, elfin birds of our pines and firs.

 

They are harder to see than hear; they don’t seem shy, but they are small, and much of their living happens far over our heads. Nuthatches are built for prying insects from the bark of trees. Their bill is slightly dished up and stout enough to shovel bugs from crevice hide-aways. Their shoulders are broad, relatively speaking, and provide the heft to wield their strong bills. Their long hind toe is used, uniquely in the bird world, to hold them in place while they hunt face-down on a tree trunk or branch. Their tails are stiff, allowing them to prop against a tree as they pound against it.

And what do they pound? In addition to picking insects from cracks in tree trunks, these nuthatches gather seeds from cones at branch-tips. They often wedge hard pine-nuts into crannies in the bark and then crack them open with hammer blows from their bills. Also, these versatile gymnasts, like woodpeckers, carve out their own cavities for nesting. No fools, they prefer the softer wood of dead limbs and snags for their home-building.

Males often begin several nesting holes as part of their courting. A female takes over and shapes the chosen cavity to her liking, taking about two weeks to complete the excavation. Both adults apply sap to the hole entrance–he on the exterior, she on the interior. The tiny nuthatches dive right through the hole without getting gummed up, but predators, from owls to ants, can be deterred by the sticky goo.

He begins feeding the female, and she lays a handful of eggs in their nest. The young hatch, naked and blind, after two weeks of incubation. Another two weeks and, having been fed and protected by both parents, the young fledge into the world.

There, if you enter that world of the conifers, you may be able to see them. A little luck and a decent pair of binoculars will let you enjoy the red-breasted nuthatch’s gray-blue back, chestnut underside, and black eyeline under a white eyebrow. Otherwise, at least you may enjoy their ubiquitous song–ankh, ankh, ankh…

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