Tag: Arizona

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.

Living Jewels that Seek Fire and Eat Wood

Among the most important components that power the machinery of forest life are insects – beetles in particular play crucial ecological roles in forests.  One of the largest beetle families is the Buprestidae, represented by nearly 16,000 species. These creatures are known as “jewel beetles” due to their family’s spectacular array of iridescent colors and patterns. The insect pictured above is one dazzling example, native to the coniferous forests of the Rocky Mountains.

One of the world’s largest jewel beetles is Euchroma gigantea, native to Amazonia. These insects can measure over two inches in length. This is a mounted specimen from Brazil, part of the author’s collection.

In most living organisms, iridescence is enabled by pigmentation. Jewel beetles are different – their iridescence is structural in origin; microscopic texturing on the surfaces of their exoskeletons selectively reflects specific frequencies of light while absorbing others.

Most jewel beetles lay their eggs on dead or dying trees. Once the eggs hatch, the beetle larvae go to work, chewing their way through the wood. They leave a maze of tunnels in their wake. Some species of jewel beetles will lay their eggs only on freshly burned trees. These specialized insects are known as pyrophiles (literally, “fire loving”). Forest fires create a nearly instant Shagri-la for them.

The larvae (or grub) of a jewel beetle found inside a section of velvet mesquite wood. These larvae are often known as flathead borers due to the shape of their heads. The tunnels that such larvae create in dead wood are of great importance to forest ecology.

Pyrophilous jewel beetles have evolved specialized extra-large wing muscles to enable long distance flights to wildfire sites. These beetles have a way of finding burned trees that borders on the miraculous…

One of the buprestid beetles native to velvet mesquite bosques in southeastern Arizona. Note the heavyset, thickened body of this insect, a specialized morphology that allows room for large, powerful flight musculature.

When they fly, these beetles hold their bodies at an angle, in order to orient their underside to the direction of travel.  Minuscule texturing on the ventral side of the insect’s thorax functions mechanically in response to incredibly faint traces of infrared radiation (heat). Infrared radiation causes a pressure differential to occur in the thorax texturing. This fires neurons, sending a message to the beetle’s brain. The message says “fly in this direction and you will find a smorgasbord of freshly killed trees to provide food for your offspring.” What is even more amazing is that these insects can detect the heat given off by fires at distances up to fifty miles!  (research conducted by Dr. H.P. Bustami and associates at the University of Bonn [in Germany] brought this astounding facet of jewel beetle biology to light.)

A living jewel adorned with iridescent gold flecks and shimmering purple-sapphire elytra, this native buprestid inhabits local mesquite bosque habitats.

This relationship between forests, fire, and beetles has been going on for countless millennia. However, people often take a dim view of beetle larvae drilling tunnels in trees, claiming that this ruins otherwise “valuable” wood. Such anthropocentric views are myopic, for they exclude the needs of all other living things and turn a blind eye toward the ecology of forests. Jewel beetles benefit forests as agents of decomposition; the tunnels that their larvae bore in dead trees provide important open pathways for other insects and for the introduction of fungal spores. The tunnels facilitate the exchange of gasses in the wood and furnish the perfect moist, insulated, dark environ for fungi to take hold. Fungi are crucially important to living trees, to the health of the soil, and for their leading role in the recycling of nutrients via the decomposition of dead trees and other organic detritus. No forest on Earth can exist without fungi and decomposition.

This maze of tunnels was bored by jewel beetle grubs in a dead limb on a living velvet mesquite tree. Read the text above to discover why these tunnels are so beneficial to forest ecology.

This is a limb that was cut from the same tree as the one in the preceding image. However, this limb was cut when it was alive. Note the scarcity of holes and tunnels. Most jewel beetles lay their eggs only on dead wood, but there are a few exceptions to this rule.

Here in the desert southwest, jewel beetles are usually easy to find almost any place where trees are present. I have also found them rather often in upland desert habitats – areas that are essentially treeless. Buprestid beetles fly into these places seeking nectar and pollen meals from the wildflowers and flowering shrubs that grow there. Thus, they provide another important ecological function by acting as pollinators.

A Big Buck in His Prime, New Life, and Rescued Wildlife

Winter brings many changes to the activities of our local wildlife. Mule deer move into the mesquite bosques to feed and find shelter. Last year, a magnificent buck lived here, in the company of many does. On a late December afternoon, he stepped out into the light, his neck characteristically swollen in the midst of rut, muscles rippling beneath a sleek coat of winter fur, polished antlers gleaming.

During these stressful times when so many lives are being lost due to the pandemic, it is reassuring and soul-warming to witness death’s opposite: new life coming into the world. A few days ago, I looked out my window to see a herd of javelina, some of them less than 20 feet distant, heading for our bird-feeding area. At this time of year, this group of nearly 20 javelinas visits our place every day and also during the night – seeing them was no surprise, were it not for the newcomers. Several of the adult females had tiny young in tow, varying in age from one or two days to about a week.

Baby javelinas follow closely behind their mothers. Unlike many other native mammals, javelinas do not have a set time of year to give birth, but several females have appeared here recently with newborn young.

When javelina are very young, they often remain nearly hidden beneath their mother’s bellies. They are so tiny that it is easy to miss them as a herd wanders by. I have never pictured adult javelinas as cute or endearing, but a mere glance at one of their stubby-legged babies can quickly reshape one’s views. Those little buggers are, in a word or two, downright cute. They can become otherwise as adults, fouling bird watering dishes, forcing any attempt at gardening in this valley to include stout fencing, and eating much of the bird seed that we scatter for our avian friends. On one occasion, our dog was nearly killed when it charged directly at a full grown javelina. In a split second, the dog was howling in pain as it returned at top speed with a life-threatening gash. Javelina are powerful and deceptively quick. They are well armed with a set of formidable, self-sharpening tusks. The poor little dog simply did not know any better. I did not reach for a rifle after the event occurred. The javelina was simply defending itself; in my mind, it had as much right to be on our land as we do. “Our” land is a place shared with other life. Enough said.

A javelina explores the world with its mother only days after its birth. Female javelinas are protective of their young, as all good mothers are. It is wise to give them room when very young offspring are present.

A year ago, another visitor appeared on a cool winter morning, an animal in serious distress. A hooded skunk had been lured by curiosity to the edge of an empty pool on our property, where it slid down into the bottom, only to find itself suddenly trapped. The vertical walls of that small pool are 5 1/2 feet high. Skunks are not built to be high-jumpers or cliff scalers. Normally, I keep an escape ramp positioned in the pool; a long 2×6 board. I had removed it the day prior when I had cleaned some debris out of the pool, but for whatever reason, I had not replaced it afterward. As soon as I discovered the trapped skunk, I replaced the ramp, sliding it down into the pool gently so as not to put the animal into defense mode. It did not take long for the skunk to walk up the ramp, out of the pool’s clutches.

Empty pools are wildlife traps. A simple escape ramp can make all the difference. Such ramps are also recommended for livestock watering troughs, allowing birds and other small animals a way to get out. A small amount of kindness can go a long way. Here, the hooded skunk ascends its way to freedom.

Once free, the skunk began to amble about, seemingly unruffled by its prior confinement. It was searching for food, and hardly paid me or my wife any mind as it stood less than ten feet from us. I have encountered other hooded skunks in the valley before…every meeting with these creatures had left me feeling that they were utterly inoffensive and little concerned with my presence. Some neighbors reach for a shotgun when  skunks come near their dwellings. Doing so shows a distinct lack of respect for other life and a lack of knowledge when it comes to coexisting with certain wildlife. Much like rattlesnakes, skunks are shy and inoffensive, unless they feel threatened. I know that if I were as small as a snake or a skunk, I would want some potent defensive measures. The rules are simple: maintain distance between oneself and such creatures and leave them alone. Maintaining distance assures one’s self protection. Leaving the animals alone and undisturbed shows respect.

Hooded skunks grow tremendously long tail hairs, a beautiful hallmark of their species.

Skunks bring special distinction to this part of the nation, for their kind are represented by four species here: striped, hooded, hognose, and spotted. Five species of skunks inhabit the United States. Only in a small part of southern Texas, southern New Mexico, and southern Arizonado the ranges of four of the five species overlap.

The skunk was in no hurry to run away after it was free of the pool. It wandered slowly, searching for food, as we stood watching less than ten feet away. This creature was mellow, inoffensive and beautiful; never once did we think we might get sprayed.

Reading Land: Decoding Rattlesnake Tracks

I thought I knew something about rattlesnakes before I moved to Arizona. I had spent decades in Montana, where I had interacted countless times with the single species that lives in that state, Crotalus viridis, known as the prairie rattlesnake. The signs that these snakes left of their presence on the land were usually limited to shed skins, skeletal fragments, or scats. I rarely saw their tracks for the simple reason that the prairies that I roamed in were completely covered with grasses and other plants.

Most snakes leave tracks like this, their serpentine form easily recognized.

Here in southern Arizona, a different situation presents itself, for there are plenty of open areas in the desert where tracks appear readily and often. When I first arrived here, I thought that snake tracks were snake tracks and not much more – until I discovered that rattlesnakes often leave very distinctive trackways. Unlike most other snakes, rattlesnakes crawl in a distinctive manner, known as caterpillar motion. Their bodies remain very straight (rather than sinuously curved) when they travel across the landscape. If a rattlesnake is in a big hurry, it will leave “S”-shaped tracks, curving and sinuous like other snakes. But these vipers are rarely in that much of a hurry, so it is far more common to find their straight trackways, a hallmark of their kind.

Rattlesnakes most often leave very straight, distinctive trackways like this one found on the dusty floor of an Arizona barn.

When rattlesnakes want to stop and rest, they invariably curl themselves into tight, circular shapes. If they have rested on a sandy or dusty substrate, they will leave behind another very distinctive rattlesnake trademark, a circular crater often dug one or more centimeters deep into the ground. No other Arizona snakes that I know of assume this distinctive at-rest posture.  Rattlesnakes do the great majority of their hunting in such a stationary, circular posture, where they wait, motionless, for prey to come by. Thus, these snakes are referred to as “ambush predators.”

When at rest, rattlesnakes curl into a tight, circular shape, leaving distinctive craters in the substrate. Here, even the snake’s rattles have left a clear impression in fine, dusty soil. The blue ruler, a standard item in many of my track photographs, measures 6 x 1 inches. For this part of Arizona, a crater of this width represents an average-sized western diamondback rattlesnake about three feet in length.

Why did such behavior evolve in these reptiles? Ambush predators rely on concealment. Most animals, including people, immediately recognize the unmistakable serpentine form of a snake. By assuming a non-serpentine look, rattlesnakes can hide from both their prey and their predators more effectively. I have encountered many diamondbacks and other rattlesnake species, and I can say with conviction that when these creatures are at rest in their usual circular posture, they can be extremely difficult to spot. That is one reason why I usually wear heavy boots and snake gaiters when I am hiking during the warm months. A little prevention can go a long way. Some of the rattlesnake species in southeastern Arizona are exceptionally potent. The average cost of treatment for snakebite is now over $75,000!

Western Diamondbacks Making Love in My Shed

Three days ago, I awoke in the morning to find an interesting story written in the fine dusty soil that forms the floor of a three-sided outdoor shed on our property. One side of the building is open and often attracts snakes to enter, where they find hiding places in the shady interior. A look at the ground told me that a pair of rattlesnakes had been courting and possibly mating there the night prior. I spotted them shortly thereafter, only a few feet away, resting together. As I watched, the male snake would crawl over the top of the female while making short, forward jabs of his chin along her back. These snakes have evolved a very tactile courtship behavior. If stimulated for a sufficient length of time, the female will usually allow the male to mate. Viable sperm is stored in the female to produce young the following spring. Western diamondbacks also mate in the spring and give birth later in summer. What amazed me about this pair was that this courtship has continued for nearly three days! 

  • The female is partially obscured and at rest here, as the male continues to crawl over her...
    The female is partially obscured and at rest here, as the male continues to crawl over her…
  • The track patterns that appeared in the morning strongly suggested that they were made by courting diamondbacks.
    The track patterns that appeared in the morning strongly suggested that they were made by courting diamondbacks.