June is upon us – a time of withdrawal in the Sky Islands. Soaring temperatures and single digit humidity levels proffer desiccation and death to unlucky flora and fauna. Entire species retreat to their Plutonian underworld where they await cooler and wetter times. Yet amidst this mass vanishing act many local snake species have evolved to thrive in these otherwise most challenging of times.
It may surprise many that snakes are in fact just highly specialized lizards. Gila Monsters, as an example are actually more closely related to snakes than they are to most other lizards! Most snakes lack any vestiges of limbs, nor do they have moveable eyelids or external ear openings.
While our region is known to harbor the most lizard species in the U.S., we also contend for the most species of snakes. Arizona is home to 52 snake species. Our Sky Islands host about 42 of them. The U.S. contains 142 total snake species, thus we have about 30% of all the snake species in our country in just a few local counties! Of the 17 snake families in the world we have five in Arizona, four in our Sky Islands. Let’s look at one snake species from each local group.
The family Leptotyphlophidae is locally represented by two species of threadsnake. The western thread snake and New Mexico threadsnake reach about 15 and 12 inches as a maximum length, making them among our most diminutive of snakes. The eyes of threadsnakes are represented only by dark, subcutaneous areas, rendering them blind. They also lack most pigment and appear almost albino. What need is there for eyes or pigment for a fossorial, or underground, dwelling, nocturnal snake?
Befitting their otherworldly appearance is the fact that both threadsnake species are sometimes taken by small owls into their nests. Once there, the snakes feed upon ectoparasites in the nest, and then their would-be predators release them unharmed a strange coevolved symbiosis to be sure! I have only encountered one threadsnake – the western – in someone’s backyard in Tucson.
Elapidae is a family of snakes that includes many notoriously venomous species, such as mambas and cobras, as well as most snake species in Australia. Locally we have but one Elapid, the Sonoran coral snake. Despite its rather potent neurotoxic venom, this species grows to a maximum size of just two feet. It is also slender, nocturnal and reclusive. Unlike rattlesnakes, our coral snake must chew its venom into its prey or attacker. Warning coloration red, yellow, and black bands – and its retiring habits generally render such an extreme response unlikely, as they would rather hide than defend. Most prey of Sonoran coral snakes seems to be comprised of other small snakes.
The family Viperidae includes all our ten species of rattlesnakes present in southeast Arizona. One of my favorite species is the small twin-spotted rattlesnake, as it is found in only four mountain ranges in the entire U.S., the Chiricahuas, Pinalenos, Santa Ritas, and the Huachucas. It lives in high elevation forests, where it hunts primarily lizards. I have seen it only two times in my life.
The majority of our snakes belong to the family Colubridae, which are mostly harmless, save a mild venom in a few species. The holy grail of local snakes in this or any snake family must surely be the brown vine snake, which grows to five feet long and indeed resembles a long, thin vine. I have yet to spy this elusive species, as it too is only found in a few U.S. ranges—the Patagonias, Atascosas, and Pajaritos. Its venom—mostly harmless to humans—swiftly dispatches lizards.
Vincent Pinto and his wife, Claudia, run RAVENS-WAY WILD JOURNEYS, their Nature Adventure & Conservation organization devoted to protecting the unique biodiversity of the Sky Islands region. Visit: ravensnatureschool.org