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.
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.
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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.
For many living things, effective camouflage often means the difference between life and death. I have witnessed camouflage acts that left me amazed – snowshoe hares in winter, whose fur matched the color and reflectivity of snow perfectly, or the disappearing act of a snipe crouched in grass…but lately, I witnessed a larval insect whose camouflage made my jaw drop.
One of the strangest caterpillars I had ever seen…
The creature had brashly exposed itself by falling from its perch in a velvet mesquite tree to land on a hand railing that had been painted white. It had gone from near invisibility to “How could you possibly not see me?” in the blink of an eye. Clinging to the railing was a slow-moving, two-inch caterpillar cryptically colored with dull greenish-gray skin. Hair-like filaments extended from its prolegs to form a peripheral fringe around the caterpillar’s body. The filaments served to effectively break up its outline. As if that were not sufficient, the crypsis of this larval moth went a step further, for the caterpillar’s body was quite flattened. In cross section, most caterpillars are round or somewhat ovoid, but this one had a cross-sectional shape more like a thin, gently curved crescent. This unusual shape meant that the dull-green, fringed caterpillar could literally melt into a twig or a branch to cloak itself in obscurity like a ghost in a fog bank.
Later, some research revealed that the creature in question was a lappet moth caterpillar, possibly of the genus Gastropacha. The word “lappet” is used to describe a fold or flap in a garment or headdress. Thus, lappet moths (family: Lasiocampidae) get their name from the hair-like fringes that project from their larvaes’ prolegs.
A lappet moth caterpillar that had fallen out of its element – transformed from profound obscurity to blatant visibility.
During the autumn of 2021, discoveries here in the surrounding mesquite bosque included this banded gecko that had dropped into an old bucket. These velvet-skinned reptiles are common here, but remain well hidden and inactive during daylight hours. Geckos are among the few truly nocturnal constituents of Arizona’s rich saurian fauna. I found this young glossy snake hidden beneath an old piece of plywood on the ground. Glossy snakes are often mistaken for gopher snakes. These beautiful, innocuous reptiles can reach lengths of nearly five feet. They are among this area’s most common serpents. Their scientific name is a gem: Arizona elegans.
The 2021 monsoon brought a cavalcade of change to the Middle San Pedro Valley. Late in autumn, large numbers of Empress Leilia butterflies (Asterocampa leilia) could be seen adorning the landscape. Abundant rainfall spurring rapid growth of their food plants likely played a major role in the eruption of these insects. Their caterpillars feed on desert hackberry, Celtis ehrenbergia (formerly pallida).
Take a walk in a local bosque late in late autumn and you are likely to see what look like little clumps of snow in the distance, gleaming white patches that really stand out on the dark-colored floor of the woodland. A closer look reveals a surprise; a mass of seeds from an unusual member of the dogbane family known as climbing milkweed, Funastrum (formerly Sarcostemma) cynanchoides. Unlike most other types of milkweed plants, climbing milkweed is a true vine, ascending to heights of 10-12 feet in tall shrubs and trees.
It is hard to miss the contrast between a clump of climbing milkweed seeds and the floor of the bosque.
After pollination, the flowers of climbing milkweed form pods that eventually fall to the forest floor, where desiccation causes them to split open and unfurl a beautiful array of seeds embedded in a mass of gleaming, silvery-white filaments.
A closer view reveals numerous seeds, the future of the species encapsulated within each one. Climbing milkweed is a host plant for the larvae of both queen and monarch butterflies.
Individual seeds can be carried long distances by wind currents, effectively distributing the plant’s progeny across the landscape. Wide distribution of seeds enhances the probability for successful germination and the continued success of the species.
