A Celebration of Life in the San Pedro Watershed – Native Mammals

Being  grateful for what we have is a wise way to live. With the advent of this new year, I feel an urge to share a gallery of original photographs that reflect that gratitude. It is a privilege to share habitat with the rich variety of living creatures that so grace this landscape. All of the following images, with only one exception, were taken within the watershed of the San Pedro River. All of the animals were wild and free  when photographed. Meet a few of the 90 species of mammals that live here…

This bobcat (Felis rufus) was sitting quietly near a gopher mound, hunting pocket gophers. Eventuallly, the cat’s patience paid off as it nabbed a gopher that made the mistake of peeking out of its burrow at the wrong time.

Trail cameras tend to render very poor quality images, but they do allow us to see things we otherwise might not, like the fire in this bobcat’s eyes. A highly reflective layer of cells known as the tapetum lucidum enables exceptional nocturnal vision for all felines.

The same trailcam recorded this beautifully colored gray fox – (Urocyon cinereoargenteus) a common predator here, but rarely glimpsed because of its nocturnal habits. Gray foxes are among the very few canids on Earth that can climb trees with ease.

A coati (Nasua narica) exploring an old barn. This one was unconcerned with my presence – these are not shy mammals. Coatis are native constituents of the fauna of the Sierra Madrean Ecoregion. Here, they are close to the northern limits of their range.

When mammals grow front claws to lengths like these, it can mean only one thing – that digging is a prominent part of their lives. Coatis use their flexible, sensitive noses to locate underground food sources (mostly insects, grubs, and pupae), then employ their stout claws to dig out dinner.

When they are not raiding gardens or gnawing on the electrical wires in the engine compartments of vehicles, rock squirrels (Otospermophilus variegatus) play a valuable role in the local ecology. Equally at home in the trees or on the ground, this species digs deep burrows to live in. By virtue of their relatively large diameter, rock squirrel burrows furnish secure underground retreats for a wide diversity of other creatures.

This young Mearn’s kangaroo rat (Dipodomys mearni) had become trapped in our (always empty) swimming pool. This species is abundantly distributed in the valley floor, providing food for many predators and playing a valuable role in the ecology of local native plant communities via seed consumption and seed distribution.

Coyotes (Canis latrans) are amazingly adaptable – they are among the few native mammals whose ranges have expanded considerably since the occupation of this continent by Europeans and other non-native peoples. They are also widely misunderstood and unjustly vilified by many people. Is ignorance bliss? Not in the case of the coyote.

I remember how thrilled I was to see my first javelina (Tayassu tajacu) – now I see them daily roaming through our bosque. This one had just finished taking a drink from the San Pedro River.

It would be a misnomer to apply the word “cute” to an adult javelina, but with respect to their tiny young, the adjective fits like a glove. Mother javelinas are both fearless and fierce when it comes to protecting their young, as all good mothers should be.

Desert cottontails (Sylvilagus audubonii) are quite common in this river valley, but they are not often seen due to their preference for staying in or near dense cover. Unlike precocial jack rabbits, cottontails dig burrows and care for their altricial young.

A Botta’s pocket gopher (Thomomys bottae) takes a quick, furtive look at the world of light. This mammal’s life is spent almost entirely in darkness. A keystone species, its role in our local ecology is of pivotal importance. I devoted an essay to this topic in The Life of the San Pedro River.

Here is what gives nightmares to any animals that think they are safe and secure deep in their burrows. Badgers (Taxidea taxus) are enormously powerful rapid digging machines, specialized to follow rodent burrows deep underground until dinner is served. They leave many holes in their wake as they roam large territories seeking food. Badger holes often plunge below the frost line. Their large holes can fit a wide variety of other animals and are used by numerous other species for shelter or brumation / hibernation dens long after the badgers leave them.

I will follow this post with a series of additional blog posts focused on birds, ophidians, and more in celebration of this new year of 2024.

A Mating Frenzy of Ants, the River Floods, Spectacular Fungi, and the Greening of the Bosque

Mid-to-late summer is the most exciting time of year to be in southeastern Arizona; it is, by far, my favorite of the five seasons here. Locals know this time as the monsoon season, or simply, “the monsoon.” In a normal year, the majority of annual precipitation occurs during this time. Unfortunately, there were virtually no monsoon rains here in the Middle San Pedro Valley during the past two summers, resulting in a barren and desperately dry landscape. Thankfully, this summer has brought the gift of rain back to the land, with 3.38 inches falling at our location since early July, with more in the forecast. The result has been an explosion of life, much of which cannot be witnessed at any other time of year.

The tiny desert cottontail pictured at the top of this post is one of summer’s products. (A reminder to my readers: If you don’t see that image, it is because you are reading this in your email. Please click on the blog title to be redirected to my blog site (https://ralphwaldt.com), where you will see the featured image at the top of each post, and more that is not included in the email version).

Rabbits, (as opposed to hares – e.g., snowshoe hares or misnamed “jackrabbits”) raise their young in burrows and feed them milk for 3-4 weeks. After that time, the young rabbits are weaned and can leave the family group. This one was out exploring the world on its own for the first time. It was tiny enough to have fit comfortably in my cupped hand, and surely held a patent for cuteness.

Thousands of harvester ants begin to rise into the air the morning after the desert’s first major summer rainfall.

The first substantial rain of the monsoon season catalyzes desert life. Harvester ants (and other types of ants) wait for that particular rain to enable the most important annual event in their lives. In early summer, the ants produce legions of special individuals deep underground, individuals equipped with wings. Their purpose is to reproduce and disperse  across the landscape. The day after the first rains, tremendous numbers of winged male and female ants flood from their nests to mate, rise by the thousands into the air, and fly away. This is a true spectacle to behold, an event that typically can be seen on only one day of each year. Freshly inseminated females (queen ants) quickly dig out a new nest and begin to lay eggs, thus founding new colonies. 

So why the big deal about ants? If I were asked to name some of the most critically important players in this ecosystem, ants would be at or very near the top of the list. They are extremely numerous – they mix tons upon tons of soil – they disperse large quantities of seeds – and they aerate the soil, allowing for better gas exchange from atmosphere to soil, along with enhanced rain percolation into the soil. These points do not tell the full story of how ants are crucial to ecosystems, but they do serve to shed light on their exceptional ecological importance.

A living curtain of ants gains altitude, rising into the sky to begin journeys that will result in widespread dispersal across the land. Sights like this typically occur only on one single morning each year following the first monsoon rainfall.

Among the many effects of the summer rains is the repetitive flooding of the San Pedro River. The river grows rapidly after every major rainfall, sending torrents of flood water downstream. These floods are of great benefit to the riparian forests that line portions of the river’s banks, for they enable the cottonwood and willow trees to continue thriving as they recharge vitally important aquifers. These aquifers nurture the riparian forests and supply water for domestic and agricultural wells.

A rural road crossing on the San Pedro becomes impassable after rainstorms swell the stream. During most of the year at this location, the river is a mere six inches deep and less than ten feet across. When I took this photograph, the San Pedro had already receded quite a bit after a good run that had swelled the river to a width of over 150 feet and a depth of roughly 12 feet.

July brings the ripening of mesquite pods (or “beans”). This year, a good crop has literally covered the floor of the bosque. These pods – high in sugars, proteins, and fats – are a pivotally important food source for an incredibly long list of native creatures. Few, if any, native plants are more important or more beneficial than mesquite to this valley floor ecosystem.

A windfall of food for everything from mice to bears colors the floor of the bosque (Spanish for “woodland” or “forest.”)

These velvet mesquite seed pods are one of the most abundant and sought-after foods for local wildlife. They were also a staple food item in the diets of indigenous peoples.

In response to the photoperiod and summer’s warmth, rains, and raised humidity, many species of fungi reveal fruiting bodies. Among the most spectacular are growths of polypore mushrooms that emerge from the trunks of certain trees…

The fruiting body of this fungus sprouted from a mulberry trunk suddenly; within a matter of a few days it measured over 16 inches across.

A closer look – I believe this is Laetiporus sulphureus, commonly known as “chicken of the woods.”

Due to a near absence of monsoon rainfall, the floor of our mesquite bosque has been barren of understory plants for the past two years. The great gift of this month’s rains have brought the color of life back to the land, vivid green that feeds my soul while providing food and cover for many living things from microbes to vertebrates. With just a few more rain storms, this mantle of new growth is capable of rising quickly to heights of six feet or more.

Rain awakens countless seeds long buried in the duff, coloring this desert world with chlorophyll, a synthesis of the merging of soil, sunlight, and water into life.