Month: March 2021

A RAVEN’S UNFORGETTABLE COURTSHIP DISPLAY, RARELY SEEN!

“One thousand feet above the valley floor, a large bird cuts an arc across a universe of clear azure sky. The bird is black, so black that it pierces a hole in the heavens, a mysterious place where all light gathers to coalesce into an extraordinary being. It is a creature wrapped in a cloak that dines on light, a creature that melts into the darkness of midnight but lives to greet the morning sun. It is an exquisite merging of feather and form, a fusion of mind and voice that we know as the raven.”

That is how I opened the essay on ravens in my new book, The Life of the San Pedro River. I have nurtured an ever-growing fascination and respect for ravens since my teenage years. Here in southeastern Arizona, my wife and I share land with a pair of Chihuahuan ravens that we have known quite closely for the past nine years. They are Mike and Mavis. Their lives have been undergoing an exciting change during the past month.

Mike maintains a daily presence here, forever welcome. His mate is almost always close by.

For six consecutive years, Mike and Mavis raised annual broods of young ravens in a nest located in a mesquite tree only 110 feet from our home. However, during the past two years, they moved to a new nesting site on a neighbor’s property some 300 yards distant, again in a tall mesquite. We missed them!

Mike digging with his beak. Chihuahuan ravens commonly cache food items for later use. Some food is placed in the crotches of trees. Far more often, these birds dig holes, drop a morsel of food into the hole, then cover the food with an inch or two of soil. Equipped with exceptional minds, ravens have no trouble relocating their numerous, well-hidden caches, even weeks later.

Despite the fact that ravens have stout, formidable claws, I have never seen them use their feet for digging, as other birds do.

Four weeks ago, I looked out my office window to see Mike fly by with a stick in his mouth. He was not heading south towards the distant nest site, but instead flew about 100 feet to the north and lit in a mesquite, where he placed the stick. That got my attention! As I watched during the days that followed, it became clear that a new nest was being built on our property.

The pair bonding between adult ravens may be closer and longer lasting than any other North American birds. Mike and Mavis are together year-round; feeding, foraging, nesting, exploring, and sleeping as a pair. That’s Mike on the left; note his thicker neck, larger head, and bigger body in comparison to his female companion.

Watching ravens build a nest is a lesson in patience, determination, and tenacity. Branch after branch is carefully selected, then carried aloft to the tree. By “carefully selected,” I mean just that – if a stick is partially rotted or otherwise infirm, it won’t do. Each stick must be within certain parameters with respect to weight, thickness and length. Once a suitable stick is found, it is skillfully balanced in the beak for the flight to the nest, then placed in a manner that is anything but random. For three weeks, I watched as hundreds upon hundreds of sticks left the forest floor to become airborne, a reverse journey back into the canopy they had sprung from. A nest took shape, growing deeper day by day. Three weeks passed, then Mike and Mavis abruptly changed their behavior. Stick gathering  had been completed, so it became time to line the nest with soft, fluffy materials. Scouring the neighborhood, the ravens found lengths of discarded baling twine, clumps of horse and deer hair, even pieces of cardboard that they ripped from a box that had been stored in an open shed. Now fully complete, the nest awaits its purpose. Soon, Mavis will lay her eggs and a new generation of some of the most intelligent birds on Earth will come into being.

The newly constructed Raven Hilton, built in the branches of a velvet mesquite. If all goes well, we will soon hear new voices emanating from the nest. Hatchling ravens produce low-volume, unique sounds that rapidly increase in volume and complexity as they grow.

One morning during the nest-lining period, both ravens came gliding through the trees to land on the ground within a dozen feet of my wife and I as we were seated under the ramada. Some very delicate, amorous preening followed as Mike ran his beak through Mavis’s neck and chest feathers. The birds were conversing with one another as this took place, uttering a soft language known only to them, a language marked by the deep-seated intimacy of a life-long pair bond that can last more than a quarter century. The preening done, Mike ambled over to within a dozen feet of us. There, he began a courtship display, hoping to win his mate’s admiration and acceptance. He lowered his stance until his body was almost flat on the ground, then fanned his tail wide. He partially opened his wings and erected the feathers on the crown of his head. His sleek indigo-black body quivered as he made a series of soft, percussive snaps with his stout beak. We were very lucky to witness this, and even luckier to get a few photographs. Only a few scant minutes of each year are dedicated to such interludes in the lives of ravens, interludes that maintain the circle of life.

Mike performing his courtship display.

As I was just about to hit the “publish” button to launch this blog post, a sudden drama unfolded just outside my office window. A red-tailed hawk made the mistake of flying too close to the new raven nest. Mike took off at high speed, chasing and diving on the hawk relentlessly. Ravens are masters of flight, a fact quickly apparent to anyone who has watched such events unfold. With very quick, elegant turns, dives, and rolls he chased the raptor for more than 250 yards before finally returning to the nest site. I have watched this pair of ravens defend their nesting sites with great vigor and determination many times. They have given brave and vociferous chase to coyotes, bobcats, a gray fox, many hawks, and more over the years. Anyone reading this who has raised children should understand such actions. I was once charged – repeatedly – by a ruffed grouse defending its chicks. Mind you, that is a bird no larger than your average chicken. I know of a Montana grizzly bear that charged and bit a slow-moving locomotive three times after the train hit one of her cubs. Motherhood and the protection of one’s young are among nature’s most powerful and important forces.

For much more on these incredible, amazing birds, read the essay entitled “Mike and Mavis” in The Life of the San Pedro River. 

For an even deeper journey into the fascinating lives of ravens, I highly recommend these two books, written by Dr. Bernd Heinrich, an astute biologist and acclaimed author: Ravens in Winter, and Mind of the Raven.

INCREDIBLY STRANGE BIRDS

Behold the common poorwill, the only bird on Earth known to hibernate! My first acquaintance with this fascinating creature happened in the late ‘80s. At the time, I was living in an old log cabin nestled into the stony folds of Montana’s Rocky Mountain Front. There, I heard an unmistakable signature call lilting out of dusk-wrapped foothills on warm summer nights, a plaintive two-note call that to some, sounds like “poor – will.”

Summer after summer, I heard their voices – sometimes I would  glimpse one in flight. Much about poorwills remained a mystery to me, until one fateful evening. As I was driving up a dirt road, a small bird abruptly rose up in front of my pickup truck. The resulting collision was unavoidable. I stopped immediately, dismayed to find an inanimate lump of feathers caught in the grill. Gently, I extricated the bird and gazed at its limp form in wonder; cupped in one hand, its warm feathers felt gossamer-soft. My attention was immediately drawn to its head, quite large relative to the rest of the body. Two huge, liquid eyes characterized the bird’s visage. What looked like a ridiculously tiny beak barely poked out from a covering of feathers. The area around the beak (and the rest of the bird’s hidden mouth) was festooned with a fringe of curved, jet black, semi-rigid bristles. 

Now it gets even weirder. I had read up on these birds, so I knew that they were grouped in a strange family known by several names:  frogmouths, nightjars, or goatsuckers. (Yes, goatsuckers, but that is another story altogether.) Curious, (as any naturalist should be) I pried  the beak apart. My jaw fell in synchrony with the yawning beak, for the beak did not merely open; the bird’s head nearly split in two! The hidden edges of the beak extended far back to form an absolute cave of a mouth, a great, gaping maw that could make any shark jealous. Why such a mega-mouth, and what was with those bizarre bristles?

Poorwills are highly specialized to feed on flying insects in low-light conditions. Having a wide gullet for a mouth makes it much easier to catch insects on the wing. Their heads are unusually large because plenty of  room is needed to house the mouth and a pair of very large eye orbits. Big eyes gather more light, handy for spotting prey in the dark. 

Here at the interface of the Sonoran and Chihuahuan Deserts, habitat like this is well suited for poorwills. A scattering of low shrubs, cacti, and plenty of open ground in between provides these amazing birds with unobstructed views and open flight paths to help them catch flying insects.

Some ornithologists speculate that the stiff bristles form a sort of tactile net around the mouth, effectively enlarging the bird’s open mouth.  This increases a poorwill’s chances of success when chasing its evasive flying food. During the heat of summer, these desert-dwelling birds reveal another advantage enabled by their gigantic oral cavities. As they roost during hot days, poorwills open their mouths while fluttering the muscles in their throats, cooling themselves in a manner similar to a panting dog. The efficiency of such a cooling method is substantially amplified due to the large surface area of the bird’s mouth.

A close look at a poorwill’s head reveals the long rictal bristles that fringe their mouths.

So what about poorwills and hibernation? Here, in the Sonoran and Chihuahuan Deserts, poorwills crawl into rock crevices where they go into a state of hibernation or extended torpor (these terms remain somewhat ambiguous) for months during the winter. Their respiratory rate and heartbeat drops substantially, while their body temperature plummets to nearly 40° F.! An astute scientist is credited with “discovering” that poorwills hibernate as he conducted research on them in 1948. However, indigenous peoples knew this long before 1948. For example, the Hopi Indian word for poorwill is (roughly) hölchoko, translated as “the sleeping one.” Thus, much like Columbus, the 1948 discovery simply revealed knowledge to a different culture, knowledge that was already known to another. (With respect to Christopher Columbus, it is impossible to “discover” a place where people already live. A combination of cultural condescension and arrogance can imprint our history books with less than the truth.)

There is much more about poorwills that makes them such captivating, beguiling birds. Their camouflage is utterly incredible. Poorwills roost on the ground where they literally merge with their surroundings. The cryptic patterning of their plumage renders them extremely difficult to spot. On more than one occasion, I have nearly stepped on them before they revealed themselves through movement. The genus name for poorwills is Phalaenoptilus, ancient Greek for “moth plumage.” (Our birds are a very unique species, for no other bird on the planet shares their genus epithet.) The scientific name Phalaenoptilus is fitting in two ways, for many moths are extremely well camouflaged, and moths make up a large part of a poorwill’s diet.

Don’t let the red eyes fool you! This is an artifact of the light projected by a camera flash. When seen in natural light, the eyes of poorwills are very deep brown or black in color. Read the following paragraph for more details.

Like other members of their family, poorwills possess a special layer of cells at the back of their huge eyes known as the tapetum lucidum, rarely found in other birds. These cells allow them to see much better in low-light conditions. As for the glowing red eye in the photographs, that results from light reflected from the choroid, a thin layer of connective tissue surrounding the outer periphery of the eye. The choroid is nourished by a rich supply of capillary blood vessels, hence the red color. (The “red eye effect” sometimes seen in photographs of people is caused by similar choroid reflectivity.)

Weird enough? Not quite. On the Montana evening when I held the unfortunate poorwill in my hand, I had missed something: the bird’s feet. Poorwills possess pectinated claws (one per foot) with comb-like, serrated ridges that are used to preen plumage and to rearrange the rictal bristles. There is also the fact that these birds do not build nests – they simply lay their whitish, non-camouflaged eggs on the open ground. How they manage to keep their species alive via such seemingly risky egg-laying habits may seem enigmatic, but it works, for there are poorwills year after year. Here in the uplands and mesquite bosques of the San Pedro River Valley, their lonely calls are an intrinsic part of the desert’s twilight world.

Finally, a note on the poorwill images: they were photographed recently here in Cochise County, AZ, then generously supplied by a friend for use in this blog. Unless otherwise noted, all other photographs posted on this site are original copyrighted images by the author.