The Sky Islands region of southeast Arizona and the adjoining bootheel of New Mexico host more reptile species than any comparable area in the U.S. The numbers are staggering: 80 types of reptiles, including 32 species of lizards, 43 species of snakes – 10 of which are venomous – as well as five species of turtles. By comparison, the entirety of Europe has only about 151 reptile species.
The heat of May is primetime for our reptiles, as many are “thermophilic ectotherms,” meaning they are adapted to high-temperature environments, relying on ambient heat rather than internal metabolism to maintain high body temperatures. Most of our lizards are strictly diurnal, as are quite a few of our snake species, providing us with a decent chance to catch them sunning themselves to warm their bodies. Other species prowl by night, seeking their preferred prey under cover of darkness. Armed with a decent flashlight, you might catch some going about their predatory business, as prey populations – think rodents, birds, other reptiles and legions of invertebrates – continue to rise after our soaking winter rains.
Let’s look at some common and obscure species that are sure to pique the interest of any naturalist.
If you find yourself near a permanent or semipermanent body of water, look for the secretive Sonora mud turtle. This aquatic species is well adapted to the arid landscapes of our region, as it is able to live in – and sometimes travel overland in between – streams, ponds, artificial lakes, marshes and even cattle ponds. This small species, which reaches a maximum size of about 7 inches long, is mostly carnivorous. It consumes aquatic insects, snails, fish and frogs, augmenting its diet with a few plants. This species of mud turtle – there are two other kinds in the Sky Islands – can be active by day or night, depending upon daily temperatures.
Turning to lizards, one of my favorites is the diurnal Clark’s spiny lizard. This well-named saurian indeed has pointy scales that help to dissuade certain predators from consuming it. Rather hefty specimens can reach nearly 6 inches in length. This highly arboreal species spends most of its time in trees, where it feeds on insects, maintains a territory against rivals, mates, and attempts to avoid predators such as greater roadrunners, gray hawks and coachwhip snakes.
That scurry of claws you hear when passing a mesquite or acacia tree is often this species playing hide-and-go-seek. This is among the most familiar of sounds as we walk the trails at Raven’s Nest Nature Sanctuary – and also a key reason that we have a visiting pair of gray hawks every year.
A far more reclusive lizard species slinks its way through the leaf litter of woodlands in a few select borderlands mountain ranges. The center of distribution for mountain skinks, and in fact the only place they can be found in the entire U.S., is the extreme southern tier area of the Sky Islands. Canyon bottoms with woods, rocks, leaf litter and logs constitute prime habitat for this often hidden species. A flash of turquoise from the breakable tail is often the only fleeting hint that this small lizard is afoot. Like many of our smaller saurians, the mountain skink consumes invertebrates. Strangely, this species has been noted to variously lay eggs or bear live young in Arizona.
Finally, we turn to snakes. I have met more than a few Arizonans who are afraid of them. I respectfully point out that they are definitely in the wrong state, given our high biodiversity of these legless relatives of lizards. One of the oddest species we have is the western threadsnake. This nearly blind snake looks as if you simply added scales and two dots for eyes on a large earthworm. I’ve seen only two in my many naturalist journeys – both at night, as this snake is decidedly nocturnal. One, odd as it may seem, was in a flowerpot in Tucson. The other was traveling in one of our many arroyos at Raven’s Nest under a moonless sky. Clinging to its head scales were a few small and irate ants, clueing me into the most recent meal of this individual. In fact, ants and termites are the mainstays of this species.
As if all this were not strange enough, some small owl species capture western threadsnakes and release them alive in their nests, which some studies indicate results in increased survivorship of their owlets.
We conclude with a rather spectacular species of snake. Like our other Crotalus species, the black-tailed rattlesnake is the real McCoy when it comes to backing up its rattling and hissing threats. In a reptilian world rife with bluffers, shams and mimics, take heed when this or any other rattlesnake species is around. Black-tails are one of our larger species and possess rather long fangs. These facts, coupled with the rather placid disposition of many individuals of the species, make a close encounter quite possible. More often than not, I detect a black-tailed rattler when I am within 7 feet of it, as it reluctantly rattles or silently slithers away. Once spotted, I simply admire the profound beauty of this snake and am reminded that reptiles indeed rule the roost during our warmer months.
Vincent Pinto and his wife, Claudia, run Ravens-Way Wild Journeys, their nature adventure and conservation organization devoted to protecting and promoting the unique biodiversity of the Sky Islands region. RWWJ offers a wide variety of private, custom-made courses, birding and biodiversity tours. Visit ravensnatureschool.org.