This has been one of the driest and hottest summers I can recall here in the Middle San Pedro River Valley. During “normal” summers, monsoon rains arrive between the middle and the end of June and continue through August and much of September. The two previous monsoon seasons brought us a welcome abundance of rain, but this year has remained very, very dry. Daytime highs for the past six weeks have averaged around 106°F., with more than a few days reaching 110° or higher. This year’s highest temperature registered at a crispy 115°F. on July 17.
Our mesquite bosque remains dry, the understory of dense London rocket plants yellowed and brittle. Usually, by the end of July, this scene should be bursting with vivid green growth in the form of Amaranthus palmeri and many other native plant species.Despite our xeric summer, velvet mesquite trees in our bosque have produced a nice crop of pods, followed by a second flowering during the past couple of weeks. The trees are drawing on water from last summer’s abundant storms; mesquite has the rare ability to transport water in both directions within its extensive, very deep root system. Water can be transported deep underground and stored for later use. A fresh splay of velvet mesquite blossoms perfumes the air and reminds us that desert plants have evolved uncanny mechanisms to stay alive and even thrive under dry, difficult conditions.
Mesquite blossoms lead to garlands of bright green pods growing from pendant branches. Mule and whitetailed deer love to feed on low-hanging bunches of these young pods. When ripe, the seed pods turn yellow and fall to the ground. There, they become one of the most crucial and nutritious wildlife foods in the entire ecosystem, eagerly fed upon by a very long list of native animals from mice to coyotes to bears and many more.
Despite the drought, this was a banner year for a widespread local species known as catclaw acacia, Acacia gregii. (See the photos in my previous blog post.) Throughout the valley, these large shrubs/small trees flowered explosively. The scent from their blossoms is intoxicatingly wonderful. Much like mesquite pods, the seed pods of acacias are fed upon by a wide variety of native wildlife.
Dry conditions leave fine coatings of dust on our driveway – an excellent newspaper that I strive to read daily. This summer has revealed tracks of mice, kangaroo rats, gray foxes, coyotes, raccoons, mule and whitetailed deer, a cougar, hooded skunks, quail, doves, and other birds including this trackway of a Chihuahuan raven.A closer look at the raven’s tracks reveals their relatively large size, distinctively lobed feet, and shallow drag marks made by their posterior claws.
A mystery…last week, I noticed something I had not seen before: dense clumps of small, black native bees forming in certain graythorn (Zizyphus) bushes. I have no idea what is going on here, nor what species these bees are – there are well over 1,200 species of native bees in this ecosystem, representing the richest known bee fauna in the world.
I found this adult giant mesquite bug (Thasus californicus) roaming under my ramada the day before I posted this blog. These are large insects that are true bugs (Hemipterans) as opposed to a type of beetle (Coleopterans).
A lateral view of the mesquite bug reveals the tube-like mouthpart that it uses to feed on plant liquids. The tube is inserted, syringe-like, into the stems of plants. These specialized feeding tubes are a primary characteristic that separates true bugs from beetles.
Prior to maturation, giant mesquite bugs exist in the form of wingless nymphs. The nymphs form colonies that feed on liquids from various species of trees and shrubs. The nymphs go through several instars before finally transforming into adults, all of which exhibit these very bright red colors. The nymphs are protected with self-manufactured noxious chemicals that make them taste bad to predators, hence their aposematic coloration.
Arizona’s smallest mammals are shrews; I found this one – dead but still warm – on the floor of our bosque. This species is known as the desert shrew, Notiosorex crawfordi. Shrews are among the most highly energized, frenetic mammals on Earth. They require remarkable amounts of food – up to nearly half their body weight on a daily basis. They almost never stop moving, constantly on the hunt. I wonder how they have time to dream.
This sight greeted me a few mornings ago, when I walked outside just after dawn to see this giant centipede (Scolopendra heros) clinging to the wall of my adobe building. The broom handle gives a sense of scale. This one was just under seven inches long – and they get bigger than this, up to nine inches in length. Very large specimens measure around an inch in width across their backs, are equipped with formidable pincers, and can move at astounding speeds.
High winds snapped this velvet mesquite trunk at the location of a cavity hollowed out by Gila woodpeckers. I have seen such tree breaks many times, both locally in this southern desert and in the northern Rockies. There is a complex relationship between cavity-making birds and their varied roles in forest ecology that may be more important we know.
A close look at the exposed woodpecker cavity shows the remnants of a successful nesting season. Last month, a pair of ash-throated flycatchers raised a batch of young within the sheltered confines of this tree cavity.
This image should be entitled “HOPE”… a series of empty, dry water buckets under my roofline, hoping and waiting for the summer rains. Why collect rainwater when we have a well, particularly summer rain water? The summer storms often feature stunning amounts of lightning, which allows substantial amounts of elemental nitrogen to be carried from the atmosphere (via rainfall) down to the ground, where it greens the Earth. All gardeners should learn that summer rain water collected after lightning storms works magic on plant growth.
9/13/2020 The past week has brought us many fascinating sights and sounds here in our southeastern Arizona landscape. One of my neighbors discovered a very young ornate box turtle on his property just a few days ago. For almost two decades, I have been seeing ornate box turtles in this valley, but something soon became puzzling about them.
Box turtles this tiny are a very rare sight locally. Box turtle photos courtesy of Gilbert Urias.
In all my time here, I have yet to see a single individual that is not of adult size. No hatchlings, no young, no pint-sized box turtles. I have thought for some time that they have been having trouble reproducing successfully in this area, so these images are nice to see!
A giant mesquite bug, clinging to my screen door. The “screening” is actually 1/8-inch hardware cloth, giving a good depiction of the scale of this lumbering insect.
A giant mesquite bug (Thasus neocalifornicus) appeared on our screen door. This actually is a true bug, a Hemipteran. The growth stages of this large insect involve several iterations as bright red social nymphs. Only in their final stage of their development do these insects become solitary and grow wings that enable flight.
Mike the Raven came to visit us this morning, as always. A full essay about him and his mate, Mavis, appears in my new book, The Life of the San Pedro River.
This has been a stellar week for bird sightings. Many migrant species are passing through, or arriving to spend the winter. Among the new arrivals here the past week have been calliope, rufous, Allen’s, broad-tailed, and Anna’s hummingbirds, Nashville, black-throated gray, Townsend’s, Virginia’s, and Wilson’s warblers, lazuli, varied, and indigo buntings, Brewer’s, clay-colored, vesper, chipping, and savannah sparrows, a lark bunting, and more. This morning, as always, our resident pair of ravens, Mike and Mavis, came to visit, along with a female Cooper’s hawk that spent many minutes bathing in one of our bird watering dishes.
This Cooper’s hawk arrived during mid-morning to scatter a group of feeding songbirds.
Cooper’s hawks are exceptionally agile, quick, alert predators that fly with more than enough finesse to catch songbirds on the wing in dense cover. When small birds go to sleep for the night, Cooper’s hawks must color their nightmares!
Perched in a velvet mesquite tree, the hawk dried and preened its feathers.Not far from where the hawk was bathing, this western diamondback rattlesnake lay coiled in a typical, circular resting position, not easy to see in the undergrowth.
Our days have been very hazy this week, the sunsets a surreal deep, dusky orange, even the moon has glazed over with smoky orange hues. For Arizonans, the smoke-filled skies are a daily reminder of the horrors that are transpiring in neighboring California as the worst fire season in history wreaks utter havoc across the state. My heart goes out to all Californians, for I know what it is like to suddenly leave home not knowing if it will be there upon our return. Huge wildfires and evacuations were a part of our lives more than a few times when we lived in Montana. May the people of California stay out of harm’s way, and may the rains come!
