Among our most universal and compelling fears, one that is widespread across cultures, continents, and through vast spans of time, is the fear of snakes. In terms of simple survival, this makes perfect sense; many snakes can be lethal. For countless millennia, I am sure that people knew which snakes were dangerous and which were not.
In modern times, our culture has become so disassociated with the natural world that most of us can no longer identify what species are harmless and what kinds are not. The deep-rooted, possibly instinctual fear of snakes remains – when coupled with widespread ignorance, it results in the needless death of many snakes every year. You say rattlesnakes are easy to identify? Tell that to the many people who have killed slightly similar gophersnakes, thinking they were rattlers. Or to the screamers that wield shovels in attempts to automatically kill any snake they see.
The photograph above the title depicts a pair of mating western diamondbacks. A reminder – if you are viewing this in your email, you will not see the header images. Move your cursor over the title and click on it to be re-directed to my blog site, where the header images appear and where other images are larger as well.
What follows is a celebration of the beauty, grace, and elegance of the remarkable animals that we call snakes. Thirty-four species inhabit the Middle San Pedro Valley. Here is a sampling of a few that I have had the delight to encounter…
A Sonoran coralsnake, (Micruroides euryxanthus), a highly fossorial, nocturnal, (and therefore seldom-seen) species. The striking aposematic coloration of these beautiful reptiles is a clear warning to many would-be predators. Bites from these small snakes are very rare – and very serious. The venom is primarily neurotoxic; drop-for-drop, it outdoes any other southwestern snake for sheer potency.Sonoran coralsnakes are small, (rarely over two feet in length) shy, and retiring, preferring to hide their heads when threatened rather than strike defensively.
Gophersnakes, (Pituophis cantenifer), are Arizona’s longest serpent, capable of reaching lengths of over eight feet. These powerful constrictors are experts at preying on rodents. A special scale armors the front of their snout, enabling them to push through soil in rodent tunnels with ease. Gophersnakes play a key role in landscape-scale ecology by controlling rodent populations. This also makes them an ally to ranchers and farmers.
Sadly, many are killed by ignorant people who mistake them for rattlesnakes, and many more are intentionally killed by drivers, brutal acts that are a mark of cruel, simple-minded people.
While gophersnakes are common in Arizona, this one is very rare due to the aberrant patterning on the upper parts of its body. The usual dorsal blotches have been replaced by long, striped markings. Glossy snakes, (Arizona elegans), are quite common in the Middle San Pedro Valley. This species can attain lengths approaching six feet. At a glance, it is not hard to confuse these snakes with gophersnakes.
A Sonoran lyresnake, (Trimorphodon lambda), curled up against the wall of my adobe residence. Lyresnakes are fascinating; their large eyes feature vertically elliptical pupils, whereas most of our other snakes have round pupils. This is a nocturnally active species whose its diet is composed primarily of lizards. Lyresnakes don’t have injectable venom; instead, they secrete venom from glands in the rear of their mouths that is very toxic to lizards – but not to humans.
A typical “pink” coachwhip, (Masticophis flagellum). Coachwhips are often erroneously called “racers” or “red racers” by local residents. Coahwhips are phenomenal creatures, the true “über predators” of the southwest. Equipped with large eyes capable of exceptional long-distance acuity, coachwhips are the desert’s fastest snakes, and are surely among the fastest in the world. These are extremely alert reptiles that specialize on hunting lizards but will also consume a wide variety of other prey items. Coachwhips occur here in three color phases, with intergrades as well. The pink phase predominates locally.
I spotted this long-nosed snake, (Rhinocheilus lecontei), crawling across the dirt floor of our open shed on a warm, early summer morning. Its vivid colors and patterning are a reminder that snakes can be very beautiful creatures.
Long-nosed snakes occur in southern Arizona in two main color morphs. This is the other one, a completely different mix of colors and patterns compared to the individual above.
A California kingsnake, (Lampropeltis californiae). To me, this is one of the most beautiful snakes in Arizona, combining a chain-like pattern of cream-yellow bands set against a glossy, satin-black background. Kingsnakes are snake specialists, actively hunting many other species including rattlesnakes – kingsnakes are immune to their venoms. In addition to snakes, other foods include small rodents, eggs, and lizards.
A desert kingsnake, (Lampropeltis splendida) This species occurs locally in two primary color phases – the one pictured here is the most common. Some desert kingsnakes exhibit melanistic (all black pigmentation) coloration.Checkered gartersnakes, (Thamnophis marcianus) prefer habitats near water sources such as streams and ponds, where one of their favorite types of prey can be found most reliably – amphibians. Three species of garter snakes inhabit the San Pedro River Basin.
Rattlesnakes are the victims of more prejudice and brutal cruelty from people than all other American snakes – most often, the prejudice and cruelty arise from deep ignorance. We tend to overlook the comforting fact that rattlesnakes are among the very few toxic snakes on Earth that give us the courtesy of a warning. This western diamond-backed rattlesnake, (Crotalus atrox), is one of several that I see quite often around our buildings. Bites from this potent species are very serious, but also very rare IF one simply pays constant, close attention to where one’s feet and hands are placed when outdoors. We never kill these snakes, (nor any others, for that matter). Most diamondbacks are shy and inoffensive if left alone. Quite abundant in many habitat types, diamondbacks play a very important role in local ecology by helping to control rodent populations.
Of the world’s 36 species of known rattlesnakes, surely the black-tailed rattlesnake, (Crotalus molossus), would win one of the top prizes for sheer beauty. My wife and I spent half and hour watching and photographing this unagressive, beguiling individual. We found it basking, suspended several feet off the ground among tree branches in a walnut – velvet mesquite bosque. This one was large for its kind, close to 48 inches in length.
I had to radically adjust my search image for local rattlesnakes when I uncovered this snake in our shed, an Arizona black rattlesnake, (Crotalus cerberus), curled up beneath an inverted wheelbarrow. Before that moment, my search image had concerned itself only with the grays and dull browns of western diamondbacks; black rattlesnakes were not “known” to inhabit low-elevation places like our valley-floor bosque, situated at 3,100 feet. Since then, I have recorded this species locally several more times.
The Mohave rattlesnake, (Crotalus scutulatus), is the most potent rattlesnake in the entire American west, injecting substantial amounts of strong neurotoxic venom when it bites. This one emerged from under a stack of lumber that I had been working with, furnishing an unforgettable reminder that only fools slip their hands under wood stacked outdoors without looking carefully beforehand.
The most reliable way to visually identify Mohave rattlesnakes is to get a close look at their supraocular scales that lie atop the head between the snake’s eyes. It is difficult to do this safely without a good pair of binoculars with close-focusing ability. Diamondbacks can look quite similar to Mojave rattlesnakes, but their supraocular scales are much smaller and more numerous. Adding to identification difficulties, the two species have been known to hybridize in Cochise County.
Small and inoffensive, ring-necked snakes, (Diadophis punctatus) are common in the San Pedro River Drainage.
When threatened by a predator, ring-necked snakes may flip themselves upside-down, feigning death while revealing their striking, aposematically-colored ventral side.
Eastern patch-nosed snakes, (Salvadora grahamiae) feel like smooth satin when handled. This species is always among the earliest to emerge when the weather begins to warm in the valley, often above ground by mid-March. Note the heavy scale at the proximal end of the snake’s head, armoring for its snout as it digs underground in loose soils.
Upon lifting a pile of old branches and debris one day, I exposed this incredibly tiny snake, a highly fossorial species I had never seen before.
My first thought was, “I never knew earthworms lived on our bosque,” until I looked closer and picked it up. Coiled in my palm with room to spare was this amazing western threadsnake, (Rena humilis). Threadsnakes prey on ants, ant eggs, ant larvae, and termites. They are a favorite prey item for Sonoran coralsnakes.
Replace ignorance with knowledge. Be kind to snakes.
The snake pictured above is a black-tailed rattlesnake, Crotalus molossus. Of the nine species of rattlesnakes inhabiting Cochise County in southeastern Arizona, this one is my favorite. (If you don’t see the image, it is because you are reading this in your email. Click on the blog’s title to be redirected to my blog website for a better, more inclusive experience. Once there, simply scroll down the title page to quickly find this most recent post.)
If snakes could talk, when asked the question “what is hell?,” they would likely answer “any place where people are.” Many people kill snakes on sight, and others run them over with vehicles – often a brutal, intentional action. If snakes have dreams, surely one of their worst nightmares would involve becoming entangled in certain types of fencing, like chicken wire or plastic mesh. A snake can slip its head through the openings in these kinds of fencing easily. The trouble comes as the reptile moves forward. As the body thickens behind the neck, there comes a point when the snake becomes trapped. Scales on snakes overlap and point backward. The wire or plastic mesh gets caught under the scales, making it impossible for the snake to back out. A long, slow death is the inevitable outcome. I have seen live and dead snakes trapped in fencing more than a few times, especially in chicken wire and in various types of plastic mesh and bird netting. The bottom line is simple: if you care about snakes, don’t use these types of fencing! Find another way.
Late this summer, a neighbor called requesting my help to free this 4-foot Sonoran whipsnake, (Masticophis bilineatus). The snake was badly entangled in some plastic mesh fencing. It took quite some time with a pair of small scissors to free the snake. This feisty whipsnake tried to bite me repeatedly during the delicate procedure.
Sonoran whipsnakes are among the desert’s most beautiful reptiles. They are capable of incredibly fast movements much like their cousins, the coachwhips. Large, capable eyes give this creature excellent long-range vision for hunting its prey and avoiding predators. These snakes are semi-arboreal, often found high in the mesquite trees, where they move with skilled grace in search of lizards and bird nests. This one had skin that felt like fine silk, remarkably smooth to the touch.
October brought this 3-foot Sonoran gopher snake to our residence. I have never seen gopher snakes as richly colored as the individuals I have encountered in this river valley. They are Arizona’s longest ophidians, (reaching lengths exceeding eight feet) and they are always more than welcome here. Few predators are more adept at capturing mice, rats, and pocket gophers, for these animals can do what most other predators cannot – they can crawl down into the rodents’ burrows. Nowhere else have I seen box turtles as gorgeously marked as our local variety. This is an adult – some of these turtles lose their stripes, fading to a solid brown as they get older, but not this one. The species is Terapene ornata, otherwise known as the ornate box turtle.
Yet another Gila monster visited our property this year. This one was an adult measuring close to 14 inches in length. These lizards are readily identifiable as distinct individuals, for their complex markings are never the same, somewhat like our fingerprints.The track of an opossum may be a common sight east of the Mississippi, but here it is something special. Most of the opossums in this valley are representatives of a Sierra Madrean subspecies, reaching the northern tip of their range here in SE Arizona. This distinctive footprint, along with others, appeared in the fine dust under my ramada early one morning.
Southern Arizona is among the top places in the nation for frequency of lightning strikes. Summer monsoon storms can be fierce and utterly unforgettable, particularly when they occur after dark. On the first day of September, a bolt slammed to the ground some 55 feet from where I had been seated. The bolt followed this upright support post on an open shed as it made its way downward. The carbonized streak is clearly visible on the post. The electromagnetic pulse from this strike fried our home telephone system.
I am happy to report that the Middle San Pedro Valley has finally received some summer rain! This has been a very dry summer – during July and August, we have received only .63 inches of rain. Most of that has occurred during the past four days. The summer “monsoon” season is what literally defines this ecosystem – enabling much of the rich assemblage of plant and animal species that makes this part of Arizona such a remarkable place.
Despite the extended drought, the velvet mesquite trees in the local bosque have put on a tremendous spurt of foliar growth this year. Additionally, the trees have flowered three times since spring. As I write this, the ground under the trees is plastered with a heavy crop of “beans,” the nutrition-packed seed pods that are one of the cornerstone food sources for our wildlife. How can this happen during such a bone-dry, hot spring and summer? The answer is rooted in last year’s very wet monsoon season. Mesquites have a remarkable ability to move rainwater down their roots, where they store it at depth for later use. That’s right; these trees can move water in both directions in their root systems! The big bean crop owes its genesis to last year’s stored rain water.
Wind plays a pivotal role in the ecology of velvet mesquite trees. When the seed pods are ripe, winds accompanying rain storms can release astounding quantities of pods in very short periods of time. Pods on the ground then become available to all wildlife, not just the species that climb trees. Mesquites depend upon animals to remove the tough outer seed coating by chewing and gnawing on the pods. The seeds of mesquite trees are able to germinate only after the outer husk is removed. This beautiful bumblebee appeared last week, an uncommon insect in local bosques. The ecology of bumblebees is intimately woven around the activities of small rodents. Local bumblebees make their colonial nests in the abandoned underground nests of mice and kangaroo rats.
Iridescent scales glitter on the back of this Clark’s spiny lizard, at rest in the shade of my ramada on a 108°F. day. Prime habitat for this species are mesquite bosques, where the trees offer an abundance of shade and escape routes from predators. Clark’s spiny lizards can climb trees with the speed and agility of an over-caffeinated squirrel.
Within the sheltered confines of a small depression in the joined trunks of two mesquites is a small rodent’s dining room – in this case, likely an Ord’s kangaroo rat. Note the many chewed fragments of mesquite pods. Kangaroo rats and many species of mice prefer such places to gnaw on their foods.
As of this writing, the raven family is still together as the trio of young birds explore their new world, constantly learning from their devoted parents. That’s papa Mike in the foreground, Mavis in the background, and their rowdy, inquisitive kids in between.
Mavis eyes up one of her favorite foods. Large eggs like this one must be held in the bird’s beak with skill and finesse. She sauntered off with this one, walking some 90 feet into the bsoque, then gently dropped the egg, dug a hole, placed the egg into the hole, then covered it with soil and duff. The spatial cognition and spatial memory of ravens is astounding. Hundreds of food items get stashed in tree crotches or buried for later use – with uncanny ability, the ravens remember where every one of them is hidden. This morning brought us a seldom-seen spectacular visitor in the form of this Gila monster that was crawling along the foundation of our home.
When viewed dorsally, the reticulated patterns on the backs of Gila monsters really stand out – patterns that are mirrored in the art of many native southwestern cultures and tribes. No two Gila monsters are patterned alike, so photographs can identify specific individuals. This one is an adult, about 14 1/2 inches in length.
For the past twenty years or so, I have participated in a coordinated volunteer project aimed at monitoring the presence of water along the length of the San Pedro River in southeastern Arizona. Organized by The Nature Conservancy, this project provides important data to scientists, land managers, and many others on the health of the river system during the hottest and driest month of the year. The data is collected the old-fashioned way – gathered by teams who experience the river in the best and most intimate manner possible, by walking and wading. Every June, I collect a portion of this data along a rare, perennially-flowing reach of the San Pedro located in the river’s middle valley, often accompanied by friends and neighbors. This year, two wonderful friends who also happen to be great neighbors assisted me in this worthwhile and delightful task.
Since June always brings oven-like temperatures, we began walking around 5:30am along a waterless stretch of the riverbed. Almost immediately, we discovered fresh tracks of an adult black bear and a cougar, etched in dry sand. One and a half miles in, the magic of water appeared. From that point on, the river flowed steadily. Because the brush is often nearly impenetrable along portions of the riverbanks, we waded, a much easier way to travel as long as one can avoid hidden lenses of quicksand. More mammal signs and tracks appeared; Coue’s whitetail deer, mule deer, javelina, coyote, bobcat, raccoon, coati, skunks, cottontail rabbits, mice and rock squirrels. Familiar bird songs spilled from the forest; summer tanagers and kingbirds, ash-throated flycatchers and song sparrows, southwestern willow flycatchers and black phoebes, grey hawks, tyrannulets, northern cardinals, Lucy’s and yellow warblers, and more.
The river in June is a different world from the surrounding vastness of desert habitat types – humid, verdant with profuse life, cool and shaded. It feels and smells almost subtropical. So much life graces the river and its forests in June that these annual walks have become my favorite time to explore and experience the beauty of the San Pedro.
Wading this desert river in the heat of June is magical. The cottonwood-willow forest stands tall and green, casting shade and coolness enabled by millions of fluttering leaves. The forest’s understory is verdant with lush growth. Eight-foot tall burr reed (genus Scirpus) plants crowd the riverbanks. Aquatic patches of speedwell (genus Veronica) glitter with multitudes of blue-purple blossoms. Tall willows form a vivid green arch overhanging the river. Birds sing from the depths of the forest, many butterflies, bees, and wasps drink from water’s edge, and scores of lowland leopard frogs leap at one’s every step. Below the surface, schools of long-finned dace are darting like shafts of animated light through the clear water. The continued presence of native frogs and fish are strong, positive indicators of the health of this aquatic ecosystem.
Among the most remarkable predators in the insect world, dragonflies are a common sight along the summer river. Some twenty-two years ago, an entomologist discovered nearly one dozen species of dragonflies and damsel flies that were new to science along this part of the river.
We waded for a couple of miles, feeling the warm, shallow waters of the river filling our shoes, until the waterway started to broaden and slowly deepen. I suspected a beaver dam was ahead. We climbed up on shore, then began to weave our way through a dense tangle of tamarisk and seep willow. Before long, we could see the beaver pond clearly, the water deeper and deeper, then the dam, plugging the river with a meter-tall, thirty-foot span of branches, twigs, tree limbs, rocks, and mud. I was elated to see that this reach of the river had beaver activity once again. The ecological and hydrologic benefits of beavers to this river – and many other waterways – are legion. I devoted an essay to this important topic in my book, The Life of the San Pedro River.
A cool, deep pond extends upstream of the beaver dam. Such dams hold more water within the river system, helping to recharge the aquifers that feed the river and its forest. The positive benefits of beaver ponds to plant life and many wildlife species could fill a book. Note the turbidity of the impounded water, a sign that the beaver(s) had been active there the night prior.
A moment of reflection seated atop the beaver dam before I was almost envenomated by a rattlesnake. Photo by Tom Talbott.
My companions and I slithered down the steep riverbank to begin wading the final stretch below the dam. We had taken just a few steps when one of my friends suddenly threw his arm around me and pulled me out of harm’s way. A 3-foot western diamondback rattlesnake, coiled too close for comfort along the edge of the river channel, erupted in a frenzy of rattling. The forward third of the reptile’s body was off the ground and formed into an s-curve as the snake’s glistening black tongue waved slowly, curled backwards over its snout. Fully cocked, primed, and quite willing to strike. My fresh shoe print was about 14 inches from the rattlesnake. Had I not been yanked so suddenly by my alert friend, this snake would have probably tagged me. I have never come so close, despite encountering hundreds of diamondbacks here over the course of the last two decades. This experience underscores a crucial rule that I try to teach to everyone that I take into the wilds here – you should watch where every footstep is headed during the warmer months in southern Arizona! Sometimes, that is easier said than done.
This is the snake that I stepped far too close to, coiled, rattling, and very ready to strike defensively. Note the recent injury on its back, something that may have amplified its angry mood. If I weighed in at less than a pound or two, and a huge, towering, 200-pound bipedal mammal threatened to step on me, I’d be in a biting mood too.
I have always looked forward to the month of April in southeastern Arizona, for it brings a great diversity and large numbers of migrant birds to the land – or does it? The first time that I birded the San Pedro River was in April of 1977. In a word, that was a stunning experience. The numbers of birds were incredible, as were the variety of species. Today, the story could hardly be more different.
Migrant songbirds (and other migratory species) have been steadily declining ever since Europeans began to populate the North American continent. The rate of decline was slow at first, but it has increased continually through the centuries. During the past several decades, declines in bird populations have become so severe that some birds have become extinct, while others are persisting by the thinnest of threads.
Here in the Middle San Pedro Valley, I have been participating in avian surveys and have been keeping detailed records of local bird life for 21 years. The data is disheartening, but this year has been the worst thus far. Numerous species that have appeared on schedule at our property every past April are simply not appearing. Many others are here in very low numbers. Sadly, close to 100% of these declines are attributable to mankind. Overpopulation, urban expansion, climate change, pesticides and herbicides, tremendous habitat losses, loose house cats, and more add up to a world that is becoming quieter and quieter every spring.
What is spring without bird song?
Other happenings in the natural world have been occurring as well, ones that are not disheartening. Lizards and snakes have awakened from their winter brumation to add their grace, color, and life to the land. A few days ago, a Sonoran gopher snake appeared a few feet from my doorway, followed by the year’s first diamondback rattlesnake and the emergence of Clark’s spiny lizards. Our resident ravens, Mike and Mavis, have successfully hatched yet another brood and are very busy keeping their youngsters well fed. A nice abundance of wildflowers is coloring the upland slopes.
The gopher snake mentioned above. We always welcome these harmless and beautiful reptiles. They play an effective role in controlling rodent populations.
This was a slender male, close to 3 1/2 feet in length. Sonoran gopher snakes can attain lengths approaching eight feet, making them one of the nation’s longest native ophidians.A closer look reveals the large, curved, robust rostral scale at the forward tip of the snake’s head. This kind of scalation evolved to shield and protect the heads of gopher snakes as they push their way through soil and pursue rodents deep into their burrows.
Every year in this valley seems to bring its own explosion of certain insects. Earlier this month, incredible numbers of crane flies could be seen. I recall walks where every step flushed 20 or more from the surface of the ground. Crane flies belong to the family Tipulidae, with over 15,000 species worldwide. They are a successful and adaptable group of insects, for their presence in the fossil record dates back over 70,000,000 million years.
A pair of crane flies, busy assuring that their kind has a future. These innocuous insects are sometimes called “mosquito hawks,” for the mistaken belief that they prey on mosquitoes. On a recent walk in the valley with a friend, we paused to admire this rare cristate saguaro, made even rarer by its unusual paired, symmetrical shape.
Incredibly, on the very same day, another friend was roaming the valley when he discovered this huge, cristate specimen. Photo by Gilbert Urias. April brings the return of turkey vultures. Here, one has landed to scrutinize one of our bird watering dishes. Among several unique aspects of these vultures is the fact that they have no syrinx – the organ that allows birds to vocalize. Turkey vultures can hiss by expelling air rapidly, but they cannot call to one another nor utter any sort of song.A close look at the vulture’s head reveals a large perforation in the bird’s beak. When viewed at just the right angle, one can see that the large hole goes all the way through the beak to the other side. Turkey vultures locate the majority of their food via a keen sense of smell, an unusual trait among most other birds. The perforated beak likely helps these birds to smell with great facility, channeling airflow into their nasal scent receptors. (The quality of this enlarged image is poor due to limits that my blog hosting service places on image resolution.)
Shallow watering dishes can do wonders for attracting bird life and many other desert animals as well.
A wonderful and always reassuring sight! The riparian forest that is so deeply important to the valley’s wildlife glows with a verdant spring canopy of cottonwood and willow leaves. The color contrast between the riverside forest and the surrounding uplands is strong in April. The forest – a true hallmark of this valley – is completely dependent upon the San Pedro River and its subterranean aquifers.
The Middle San Pedro Valley sprawls across nearly one million acres of undeveloped, unfragmented land in southeastern Arizona. Its slopes and woodlands, bajadas and ridges have been rimed with frost every dawn under the abbreviated touch of winter’s Sun. Days are short. The land stands hushed and still with its seasonal absence of many birds, reptiles, and other forms of life. Nonetheless, there are many good reasons to get outside and walk the land. January and February have brought a few surprises, particularly in the way of unexpected sightings of locally uncommon birds.
In late January, five purple finches began frequenting our bird feeders, thinking they were well concealed within mobs of house finches and lesser goldfinches. My wife’s sharp eyes picked them out of the crowd. In 20+ years of avian record keeping in this valley, that was the first time we had ever seen purple finches. Another species that has been sighted sparingly here during the winter months is the American robin. For reasons that remain a mystery to me, we have been inundated with robins this winter. They bring me many fond memories of their near-constant presence during past summers when I lived in the northern states.
Speaking of thrushes, another bird that I had never seen in the valley before has arrived to grace the nearby riverbottom woodlands this winter – a Townsend’s solitaire. A friend and neighbor, Tom Talbott, first sighted one about a week ago in the forests along the river not far from our home. Tom is a highly skilled birder and a masterful wildlife photographer. A few days later, walking the same reaches of the river, a friend and I also saw a solitaire. News has been spreading of numerous sightings of this species in areas just a few dozen miles to the north.
A Townsend’s solitaire perches quietly in branches overhanging the channel of the San Pedro River. These elegant thrushes are common residents of timberline forests high in the mountains of western Montana, where I would meet them again and again as I led groups of hikers during the summer months. Their songs are unique and unforgettably angelic, like no other bird I have known. Photo courtesy of Tom Talbott.
Not far from the solitaire, we found this great horned owl snoozing within the branches of a Fremont cottonwood. These owls are remarkably capable predators whose list of possible food items exceeds that of any other North American owl. Among the creatures that great horned owls have been known to prey upon include insects, amphibians, various reptiles, mice, rabbits, domestic cats, small dogs, ducks, skunks, and even porcupines.
Mid-January brought us over an inch of rain in the valley floor during one winter storm. Rainfall amounts were much higher in the nearby Galiuro Mountains, resulting in a strong winter flow for Hot Springs Wash. Such flows during the winter months are rare.
The rain enabled millions of dormant London rocket (Sisymbrium irio) seeds to sprout, providing a new source of food for wildlife while greening the floor of this mesquite bosque with the glowing color of new life.
Large numbers of these small white puffballs erupted from the ground under mesquite trees after the rain. Fungi are becoming known as some of the most important organisms on the planet. The mycorrhizal filaments of many species of fungi form mutually beneficial associations with tree roots, for example. No forest on Earth can exist without such subsurface fungal alliances.
A hooded skunk wandered under my ramada one night, leaving its signature behind in the form of these tracks made in fine, dusty soil. Note the track pattern as the animal was walking at normal speed.
A closer look at the skunk’s footprints. Even though skunks are plantigrade mammals, the heels on their back feet often do not register in their tracks, as seen here. (The hind foot is to the left, front foot to the right.)
I discovered this torpid spiny lizard spending the winter brumating underneath a plastic tub that had been set outdoors on the ground. The lizard was found at ground level, not dug in below the frost line. Temperatures here routinely dip into the teens every winter. I was taught that reptiles must spend winters below the frost line, because otherwise they would freeze and die. I have also seen a pair of diamondback rattlesnakes spending the winter under a board in an open barn. Apparently, what I was taught cannot be correct – it seems clear that these reptiles can endure a fairly substantial amount of freezing.
Darkness settles over the land. Many miles from the lights and sounds of towns and cities, Arizona’s Middle San Pedro Valley sprawls wild and still. At twilight, only a faint poorwill and a pair of great horned owls can be heard. The coyote telegraph erupts and then fades as it travels from ridge to distant ridge. In contrast to the rich variety of summer sounds, an autumnal hush blankets the countryside.
At day’s end, dusk gently ebbs into darkness as a brilliant October moon emerges from the far shores of the eastern horizon. Here, in our mesquite bosque, the peace and comfort of the night suddenly give rise to a thousand voices raised in the jubilance of courtship. These are sweet, almost melodic sounds – October’s distinctive nocturnal biophony. Tree crickets are singing from the ancient trees, thousands of them spread across the valley floor, their songs a vivid proclamation of thriving life within an otherwise quiet forest.
This species of tree cricket sings from the tall mesquites in our bosque. Its ecology is intimately connected to velvet mesquite trees. These are small insects with a big voice.
I have come to love the sounds of these delicate, gossamer-winged insects. Long after summer’s insect frenzy, when most species have faded from the scene, tree crickets come to life in the coolness of October nights. The males raise their transparent wings, then call to the females by stridulating – in other words, they rub certain parts of their bodies together to produce a surprising volume of sound. Females are drawn to these love songs. The males go one step farther by offering their mates a special reward. After mating, metanotal glands located on the dorsal side of the male’s abdomen secrete a substance that the female feeds on.
Eight species of tree crickets inhabit southeastern Arizona, where they produce two generations each year. The ones singing in local October bosques belong to the genus Oecanthus. Each species has its own unique song. However, even among the same species, sound can vary quite a bit depending upon air temperature. The frequency (or pitch) of the crickets’ songs increases as temperatures rise and slows as temperatures fall.
A bizarre butterfly landed on my screen door last week – an American snout butterfly, Libytheana carinenta. Last year, large numbers of these butterflies erupted all over the valley in late summer. Snout butterflies use their strange shape to blend in with their surroundings. When perched on a plant stem, their elongated “snout” breaks up the outline of their bodies, resembling a broken twig or a thorn. The range of snout butterflies extends all the way to South America. They are known for migrating across landscapes in huge aggregations.
A study in camouflage, the American snout butterfly sports wings that blend well with tree bark and a unique body shape that helps to conceal the insect when at rest.
This summer’s plentiful monsoon rains have continued well into October. Since the monsoon began on June 18, our rain gauge has recorded an amazing 13.46 inches of life-giving rainfall.
One of the local washes experienced some large summer floods. I took a walk down this wash with a friend a few weeks ago, to have a look at the powerful changes wrought upon the land by the big floods. What we saw was in stark contrast to the wash I had known from walks during the past several years.
During recent times, this broad wash had been covered by a wall-to-wall effusion of burro bush (Hymenoclea) standing six or more feet tall with a galaxy of roots anchoring the bushes to the ground. The flood had erased most of that growth, leaving behind a clear streambed lined with heaps of debris – tree trunks, plant material, rocks, and more. The floor of the big wash had been totally rearranged, its topography and course markedly changed during a couple of events that lasted only days.
In places where floodwaters form swirling, circular eddies, holes are dug into the wash floor like this one. These depressions can be very large and quite deep. They often hold pools of surface water that can last for months after flooding, a valuable offering to birds, mammals, and other wild creatures in this desert ecosystem.
Powerful floods like these transport thousands of tons of boulders, rocks, gravel, sand, clay, and a wide variety of organic materials – whole trees, cacti, and other plants. Downstream, entire soil profiles are altered and built as sediments settle from the turbid waters. Cutbanks collapse, dropping great layers of soil into the roiling floodwaters, releasing seeds that have lain dormant from ancient times into the present-day ecosystem. Old genetics from times long gone may invigorate plant populations and enhance the genetic variability – and hence, the viability – of modern plant communities.
Most people would simply label this collapse of a stream-side cutbank as “erosion.” That is an accurate use of the word, but I see much more going on here.
Debris piles left along the stream banks can be very large, consisting primarily of tangled, broken bushes, parts of trees, and other plant matter. They provide shelter and denning sites for small mammals, reptiles, amphibians, and other creatures. Floods are not all bad – they are simply a natural, intrinsic agent of change, some of it beneficial, some not. People often label floods as “bad,” but that viewpoint roots in anthropocentric thinking, a myopic way to view our world.
The ecology of many native species of plants and animals actually depends upon flood events. The beautiful stands of cottonwoods that line the San Pedro River could not exist were it not for floods creating the specific conditions that their seeds require for germination. The riparian forests that accompany the river depend upon having their roots tap into subsurface aquifers. The aquifers get recharged when floods happen.
As floodwaters recede, the bed of the San Pedro River leaves records of local wildlife in the drying mud. Here, the patterning of fine surface cracks results from a place where the river water subsided very gradually with little or no turbulence, resulting in the deposition of extremely fine clay particles. As these clay deposits dry, they crack in characteristic patterns.
October typically brings us the last ophidian visitors of the year, most of them not to be seen until next spring. A beautiful gopher snake was here last week, and as I write this, a diamondback is curled up a short ways from my entry door.
An October gopher snake, crawling along the wall of one of our buildings. This one was a male, measuring right around 63 inches in length. Always welcome here, as are all snakes.The year’s last generation of pipevine swallowtail butterflies occurs in October. I found this gorgeous caterpillar recently – it is either in the fourth or fifth (last) instar of its development, after which it will climb a plant stem and metamorphose into a chrysalis suspended by a single loop of silk as it waits out the winter season. The leaves visible in this image are pipevine leaves, (Aristolochia), the only plant that these caterpillars feed upon.
October is THE month for seeing pinacate beetles (Eleodes spp.) – they are literally everywhere at this time of year, easily noticed because of their large size, slow movements, and diurnal habits. When they feel threatened, pinacate beetles stop moving and assume this head-stand posture. If the threat escalates, (for example, when a bird tries to grab the beetle), the beetles fire a noxious, very disagreeable fluid from the tip of their erected abdomen. Chemical defenses are very common among many insect species.
Just a few days ago, I noticed this small tuft of feathers laying on the ground. Immediately, I began searching the area for more, because such a find usually indicates that a bird was recently preyed upon somewhere nearby.
I soon found many feathers like this, their shafts intact. Intact shafts indicate feathers that were pulled out, not bitten and yanked out as mammals do. So this was the work of a predatory bird, likely a Cooper’s hawk that I have been seeing frequently of late. This was a special find, for these feathers could have come from only one species, a gilded flicker. Gilded flickers are relatively rare in local bosque habitats.
There has been a sudden and tremendous eruption of small beetles in the local mesquite bosque. A dense, tall understory of pigweed, (Amaranthus palmeri) covers the floor of the woodland, an exuberant growth enabled by recent monsoon rainfall. When I walked into these plants this morning, curtains of tiny beetles took flight from the pigweed at my every step, thousands upon thousands rising upward like a reverse blizzard.
The leaves of the pigweed plants had become dotted with countless small holes during the last two days. This morning, the plants revealed that an orgy of feeding had taken place during the night. Literally all of their leaves had been reduced to a ghostly remnant of reticulated veins with no leaf tissue left in between. Every plant, everywhere I looked – consumed overnight.
Acres and acres of bosque understory were fed upon by an almost inconceivable number of small insects. The plants looked almost shredded.
A pigweed leaf after the night’s heavy feeding spree.
Naturally, I had to know what these beetles were. They were diminutive, measuring around 4-5mm in length. Up close, the beetles were beautiful, sporting brightly colored, broad white bands running lengthwise across their shiny black elytra. After some research, I learned that they were known as “pigweed flea beetles,” Disonycha glabrata. Their ecology entails a close relationship with specific host plants – they will feed only on plants in the genus Amaranth. I have witnessed dense growths of pigweed during most of my summers here; I had noticed these beetles in prior years, but never in such spectacular abundance. Why had their population so suddenly rocketed this year? I can only guess. Perhaps this year’s rains were perfectly timed at just the right intervals and in perfect amounts to encourage such an event? Maybe it has something to do with their predators…or some other mechanism?
A pigweed flea beetle, Disonycha glabrata.
When insects erupt in large numbers, people are often quick to react with alarm and negative attitudes. Yes, they shredded an entire forest understory – but was that a bad thing? Or simply natural change? It is not our place to pass judgement on what happens in the natural world. Both the beetles and their host plants are native constituents of this ecosystem. So, I do not necessarily think that what has happened is somehow wrong or alarming, but it is interesting.
I found another creature wandering in the pigweed last week – a young adult Sonoran Desert Tortoise! We see these reptiles rarely here in the bosque; they are more partial to nearby upland desert habitat types. This one’s carapace was between 9 – 10 inches long, and like most of its kind, it was cautious, slow-moving, and appeared unfazed by my presence.
The Sonoran Desert Tortoise that I discovered resting peacefully under the trees. This reptile and its close relatives have recently undergone taxonomic revision – to scientists, it is currently known as Gopherus morafkai.
The tortoise’s powerful front legs are clad in rows of thick, hard scales that assist in digging and may help the turtle resist serious injury from predators. When threatened, the tortoise tucks its head in and then covers its front with these remarkably well-armored legs.
A few days ago, I went out on a walk with a naturalist-friend. He shared a special area with me, a mature mesquite bosque with a remarkably rich, lush understory. I was deeply touched by the feel and presence of this almost subtropical woodland. The image below provides some insight into the kind of verdant growth that this “desert” valley is capable of hosting.
A jungle-like wall of vining plants drapes over young trees and shrubs in one of the most lush, beautiful velvet mesquite bosques I have ever seen. Just beyond the reach of this image was a barbed-wire fenceline. On the far side of the fence, cattle grazed – the ground under that part of the forest had been virtually wiped clean, transformed into a deeply impoverished world with respect to native plants and wildlife. Mesquite bosques as rich and fecund as this one have become very rare – cattle are commonplace. How is this right?
The lightning bolt slammed into the ground with thousands of times the force and speed of a sledgehammer blow on an anvil. It struck so close to me that I heard no thunder, only the unmistakably loud, monstrously powerful “snap” that is characteristic of a bolt that hits far too near to its observer. I had been sitting on my bed reading when it happened; I knew instantly what had occurred, for this was not the first time that lightning had struck so close to me that no thunder could be heard. Many years as a guide in the wilderness mountains of Montana had brought me into near-contact with lightning along high ridges at timber line more than a few times. It is one of nature’s most lethal forces when it strikes living creatures, but the other side of lightning is that it is one of the world’s most quintessentially important life-giving phenomena. For the full story, see pages 204-205 in my book, The Life of the San Pedro River. The next morning, I found the place where the bolt had impacted. A tape measure revealed that the lightning had struck 53 feet away. The electromagnetic pulse from that bolt fried our telephone system and our computer router.
The storms of this year’s monsoon season in southern Arizona have been wonderful – thus far, our rain gauge has registered 9.56 inches of rain since mid-June, resulting in a grand resurgence of life all across this hot and formerly dry landscape.
On the morning of August 20, a serious storm pounded the ground with so much rain that the area around our buildings became an unbroken sheet of water. I could hear toads starting to call from our overflowing bird pond. Before long, dozens of spadefoot toads came out of their underground lairs to join in the party, all of them hopping and swimming through the flooded landscape in beelines toward the pond. This was a critical time for the amphibians, for in a normal year, they get only one or two brief chances to breed. It was also a rare sight, for I have never seen such activity in the daytime…but this was a doozy of a storm.
Mavis – the female half of the raven pair that we share habitat with – takes shelter from the storm under the roof of our shed.
As the rain subsided, I stepped outside. I heard the familiar roar of one of our local washes that had become engorged with flood water. A short walk of a quarter mile took me to a place where I could look down from the edge of a vertical cutbank at the flowing wash…
The view from the cutbank after 2.6 inches of rain from a single storm swelled Hot Springs Wash with roiling floodwaters. Only a single channel is visible in this image. The waters braided across the broad wash floor in an ever-changing – and growing – number of channels. Powerful floods are characteristic of desert washes with large drainage areas (this wash drains an area of about 100 square miles) and steep slopes in their headwater areas.
Next, I walked over to see what was going on in the little pond – there were eight pairs of Couch’s spadefoot toads in amplexus! A couple days later, after thousands of toad eggs hatched, our pond was teeming with wriggling throngs of tiny tadpoles.
Couch’s spadefoot toads mating in our pond. Each female usually lays hundreds of tiny eggs during such couplings, as the male releases sperm into the water.After the mating frenzy, myriad spadefoot eggs clung to every blade of grass afloat in the water.
Later in the day, Kathleen and I walked down the road to have a look at where the big wash crosses the road. The sound of the flood grew loud as we approached a point where we could see the flow, over 300 feet in width. The dirt road – the only road that serves the entire valley – had become impassable once again. In the midst of the turbulent flow, where the waters ran deepest, trees were being tossed around like toys, ripped from their root-bound moorings as they sped downslope toward the San Pedro River. Hundreds of tons of sediment, gravel, and rocks were being transported toward the floor of the valley in a rip-roaring tumult of rain water.
A view of the flood as it obliterated the roadway where it crosses the usually dry bed of Hot Springs Wash. During the twenty summers that I have seen this wash respond to rainfall events, only twice have I witnessed it running larger than this.
As we were watching the floodwaters, I climbed to a higher vantage point, where I discovered this beautiful Sonoran gopher snake. The snake allowed me to gently approach within a foot or so. This was a fine specimen, over 5 1/2 feet in length.
A few hours later, the sun had melted down into the nether regions of the western horizon. My wife and I walked outside around 11:00pm to listen to the night sounds. After turning off our flashlights, we witnessed something that is seldom seen here – fireflies!! Few of Earth’s creatures are capable of instilling such an immediate and compelling sense of awe and wonder as fireflies are. They were emitting distinctive, paired flashes of remarkably bright green light – in so doing, they identified themselves down to the species level. We were seeing southwestern synchronous fireflies, Photinus knulli.
A couple of days after the big storm, I walked down to the San Pedro River. Many areas within the river’s drainage had received substantial rains, bringing the river to life. Here, el Río is surging along with a flow roughly 180 feet in breadth and over six feet in depth.
Downstream, a group of turkey vultures was roosting in a pair of dead cottonwood trees. Dead trees are an essential and important component of all forested areas on Earth. All too often, humans fail to recognize this aspect of our planet’s ecology. Our culture – embedded in the ecologically dangerous Abrahamic concept of land use – (the land is here to produce our milk and honey, for human use) – tends to see dead trees as “going to waste.” “Salvage logging” of our national forests after wildfires is an exemplification this anthropocentric view of our living world.
The rainy season brings twilight flights of thousands of buprestid beetles just above the canopy of our local mesquite bosques. Here, a very rare sight unfolds as a female Polycesta aruentis everts her ovipositor to lay her delicate eggs deep within the sheltering crack of a mesquite stump, where they will be out of reach of the sun’s touch. Her larvae will hatch to bore their way through the wood, leaving tunnels in their wake that greatly facilitate the entry of fungi and other agents of decomposition. Thus, insects like this play a critically important role in forest ecology.
A half-grown (about four inches in length) Sonoran desert toad enjoys our bird pond after a rain. These amphibians grow to prodigious sizes. If I am not mistaken, they are the heaviest toads native to North America.
Living in remote parts of the desert southwest demands some important learned behaviors. Only fools step outside without looking first. This diamondback had just finished crawling across my entry steps when I took this photo. Snakes of all kinds are always welcome on our property – but continuous caution when one ventures outdoors is an imperative part of living here.
A reminder for my readers: Please do not read this in your email program. Instead, click on the blog title and you will be redirected to my web site for a much better experience with larger and clearer photos and text. You will also see the featured image that starts off every blog post, but (for some odd reason) is deleted from these automatically generated email notices.
A few evenings ago, an uncommon view from my desk window engendered delight and a deep feeling of gratitude. The scene encompassed a wild mesquite bosque, standing tall and green in summer’s refulgence…a gentle, drizzling rain was floating its way to the ground, suffusing the air among the stout trees with the magic of a fine mist, colored soft in fading light. The land was coming alive, replete with the promise of sprouting plants, emerging fungi, and the rising scent of moist duff. A water-borne resurgence of desert life was in the making.
During the past few weeks, more rain has fallen, resulting in a cavalcade of change, a water-borne eruption of desert life. Flowers are blooming and creatures are stirring, many of which cannot be seen at other times of year. Giant millipedes are crossing roadways and threading their way through the woodlands, tarantulas are out of their burrows roaming the landscape, harvester ants are forming great clouds of alates bent on their one-day-per-year mating spree. Sonorous calls of amphibian passion are ringing through the night after every substantial rain. “Monsoon” as locals know it, is the one season that defines these lands and the ecology of southeastern Arizona more than any other. Arizona without its monsoon would be akin to Alaska without a winter.
One of many creatures that are revealed during this season is a small, nocturnal lizard with semi-translucent skin like gauzy velvet, big eyes with vertical pupils and movable eyelids, and the very rare ability (among lizards) to vocalize. Once encountered, the western banded gecko is not soon forgotten. More than once, I have heard the word “cute” applied to this beguiling little creature that rarely grows to more than four or five inches in length and remains hidden during daylight hours.
I discovered this little gem sheltering under an old piece of plywood. This banded gecko had lost its tail sometime in the past – the new one grew back lavender in color. A plump tail like this one indicates a good state of health, for the tail stores fats and water for the animal to draw upon during lean times, much like the tails of Gila monsters.
When predators chase after lizards, the first part of the lizard’s body that they make contact with is often the tail. In evolutionary response to this, many lizards have developed special abscission layers in their tails. Once contacted, the tail breaks off, leaving predators detracted by a wiggling morsel while the main course absconds to safety. Banded geckos have tails that break off with a very, very light touch; hence, I recommend against handling them.
When threatened or disturbed, banded geckos often curl their tails over their backs. Such posturing mimics the scorpions that they share habitat with, potentially scaring off some would-be predators. Banded geckos can also utter an audible squeak when frightened, making them one of the few lizards in the world capable of vocalizing.
During late July, the mass of tadpoles in our bird pond (see the previous blog post) transformed into toadlets in a matter of only ten days. The tiny young amphibians are now hopping their way into the surrounding woodland, disbursing at night when temperatures are cool.
This minuscule toadlet was photographed during its first day out of its natal pond, where it had spent the initial ten days of its life as a wriggling tadpole. At this stage of their lives, Couch’s spadefoot toads (Scaphiopus couchii), are tiny and vulnerable, fitting easily atop a mere dime.
On a warm early morning in mid-July, I took a walk and discovered an abundance of white-lined sphinx moths (Hyles lineata) almost everywhere I went. Most sphinx moths do their flying at night, but these moths were out in direct sunlight. They were specifically targeting wolfberry (Lycium spp.) bushes. The wolfberry was in flower, and the moths were hungry for nectar. With unerring accuracy augmented by rapid, graceful flight, they were moving from flower to flower, hovering at each one to insert their long tongues for sips of nectar.
A white-lined sphinx moth hovers over a wolfberry bush, deftly inserting its long tongue into the tiny white flowers to feed on nectar.
Note the bend in the moth’s tongue, a common trait among many species of sphinx and hawk moths.
White-lined sphinx moths have a very wide distribution that includes most of the United States. In some areas, their tongues are considerably shorter. Here, as they coevolved with certain types of nectar-rich flowers bearing long corolla tubes, their tongues adapted over time.
Since the first of this year’s summer rains on June 18th, we have received 4.25 inches of precipitation. Here is an image of our bosque taken just before the first rains.The same area, photographed yesterday. The difference is clear – the greening understory is composed primarily of pigweed (Amaranthus palmeri), a native plant that is of great value to a wide variety of birds and mammals. If the rains continue, this vivd understory will be capable of reaching heights of six to seven feet.This is what is left of a pigweed plant that grew after last summer’s monsoon rains. Pigweed retains much value to wildlife even after it has died and desiccated to a state like this one. Note that the plant has been recently fed upon, and that the cuts at the tips of each stem are sharply defined, cut cleanly at a steep angle. This is a signature left by the incisor teeth of a black-tailed jackrabbit. Nearly all rodents and lagomorphs (members of the rabbit order) leave such distinctive cut marks when they browse on similar types of vegetation. If deer or javelina had done this, the cuts would be rough with frayed edges and not cut at such steep angles.
Our area, the Middle San Pedro Valley, is served by a single dirt road that frequently endures serious damage after monsoon rain storms. I photographed this large wash near our home shortly after dawn, several hours after the flood had crested. The wet marks along either edge reveal a surging flow of flood waters that had crested at over 150 feet in breadth and four feet in depth. Flows this strong are quite capable of quickly carrying away almost any vehicle, even very large trucks.
