We expect rattlesnakes amid dusty rocks or dry woodland litter, sequestered in burrows or crevices – but up in trees? Turns out: sure, occasionally anyhow, as some recent headline-grabbing sightings out of the southwestern US attest to.
In July, a widely circulated video taken by Jerome Perez showed a New Mexico rattlesnake – rattling vigorously away – perched in a mesquite tree. "The snake was up high, soaking up the early morning sun, but his rattler was going at high speed," the Wichita Eagle News quotes Perez. "A small sparrow was flapping frantically in front of the snake, trying to keep it from a nest likely hidden in the tree."
Earlier this month, meantime, Tom Sykes photographed and filmed a western diamondback rattlesnake well up a tree in the San Pedro National Conservation Area in southeastern Arizona.
There’s been some social-media "buzz" (if you will) about all this, more than a few commentators suggesting canopy-draped rattlers are something strange, unsettling, and very much in line with the generally disturbing, stress-packed vibe of 2020.
Actually, it’s not unheard of for rattlesnakes to creep and slither their way into trees, though no herpetologist would rank them among the arboreal champs of North American serpents. And let’s tackle the meat of the issue head-on: The chances of a rattlesnake dropping out of an overhanging tree onto your head are mighty slim indeed. (We’ll also put this essential disclaimer right up front: Rattlesnakes aren’t in any way out to get you, and they perform vital ecosystem services as predators of rodents, rabbits, and other small critters. Also: They’re super-cool.)
Bryan D. Hughes is an amateur field herpetologist and the founder of Rattlesnake Solutions ("We like snakes so you don’t have to"), which relocates rattlesnakes from homes and yards across Arizona and installs specialised rattlesnake fences. In a blogpost addressing the recent flurry of stories about climbing rattlers, Hughes wrote that he’s seen multiple rattlesnake species in trees in the American Southwest (the centre of diversity, along with northern Mexico, for these New World pit vipers): besides western diamondbacks, also black-tailed, speckled, tiger, and banded rock rattlers.
He told me by email that most of these sightings were of rattlesnakes loosely coiled in lower boughs during the hot desert summer, when an arboreal basking perch likely helps the snakes keep cool. But some of the rattlers he’s spotted in trees may have been seeking prey. "Of the rattlesnakes that I have seen higher in trees, above eye-level, [some were] stationary snakes in an apparent ambush position to hunt birds," he said. "However, more often they are actively moving. In some instances, in particular with black-tailed rattlesnakes and speckled rattlesnakes, they are moving in trees with numerous birds and arboreal mammals, and I assumed they were moving into a position to hunt them."
In his blogpost, Hughes also shared this video of a western diamondback he flushed at night just last week, which began hoisting itself up a tree in apparent response to the inadvertent disturbance:
In other words, tree-scaling rattlers aren’t some new, devilish 2020 concoction (let alone a cause for concern). Indeed, this isn’t the first time they’ve generated online waves. In 2018, for example, Frank Gonzalez filmed a large western diamondback high in a tree in New Mexico, actively weaving its head about in the air.
Dr. David A. Steen, the Reptile and Amphibian Research Leader of the Florida Fish & Wildlife Conservation Commission’s Fish & Wildlife Research Institute and author of the recent book Secrets of Snakes: The Science Beyond the Myths, said that the New Mexico rattler looked to be exploring and suggested that – besides climbing up itself – it could potentially have even been dropped into the canopy by a bird of prey. Hughes echoed the exploratory idea, noting, "The snake appears to keep going up, not realising there’s no more 'up' to go."
Avoiding predators is one explanation for rattlesnakes in trees, alongside hunting arboreal prey, thermoregulation (read: basking), and finding refuge from floodwaters. A 2016 article in Herpetology Notes proposes that the famous sidewinder – a rattlesnake from the Sonoran and Mojave deserts primarily thought of as a sand-dune specialist – may use a perch in a shrub such as burrobush to give the snake an elevated, more secure vantage to rest while keeping an eye out for potential threats.
That said, Steen pointed out your average rattlesnake likely isn’t usually going to beeline for the nearest tree when a predator’s actually in the vicinity. "Rattlesnakes usually rely on their camouflage to avoid predators and, failing that, they do have potent venom defences," he said.
He noted that, among the several kinds of eastern rattlesnakes, timber rattlers are sometimes seen in trees – more so, for example, than pygmy rattlesnakes or the great eastern diamondback, largest of all rattlers and one of the heftiest venomous snakes in the world. A well-known painting by the early American ornithologist and artist John James Audubon, in fact, shows a climbing timber rattlesnake attempting to raid a mockingbird nest in the face of some vigorous defence.
One study from eastern Texas documented quite a bit of tree-climbing among timber rattlesnakes, particularly subadults; most impressively, a rattler was seen some 14.5 metres (nearly 50 feet) up a laurel oak. The researchers suggested larger, mature rattlesnakes may be less proficient climbers. While they posited hunting was probably the most likely explanation for timber rattlesnakes ascending trees, they pointed out that "the apparent lack of behaviours such as coiling around limbs for support, or specialised support postures used by other heavy-bodied arboreal species" probably hamper their predatory prowess in the canopy.
A previous study referenced in the Texas research recorded a timber rattler catching a yellow-bellied sapsucker, a kind of woodpecker, fairly high up a tree. But the snake tumbled down to a lower branch in the process – not exactly the slickest act of off-the-ground predation.
Generally bulky and relying on their venomous bite, not constriction, to subdue prey, rattlesnakes don’t have a body plan especially suited to climbing, as compared with more regularly tree-going relatives. Hughes said a number of Southwestern snakes of more slender build, such as coachwhips and whipsnakes, are much superior in the arboreal department. "They appear to have the ability to articulate belly muscles to take advantage of small 'footholds,' for lack of a better term, and work their way up complicated surfaces," he told me. "Rattlesnakes, in contrast, are heavy-bodied and built differently. In an apples-to-apples comparison of climbing abilities, the body and movement of a rattlesnake are not as good as the more slender generalist snakes, being better suited for a life in ambush on the ground."
"I’ve actually seen rattlesnakes fail in their attempts and fall off rock walls numerous times," he added, "so they’re a bit clumsy as mountaineers."
In the eastern US, Steen singled out rat and corn snakes – which readily raid bird nests – as particularly ace tree-climbers. These snakes, he said, "are adept at maintaining a large proportion of their body size in the air at one time. This helps them climb."
Climbing snakes commonly employ such styles of locomotion as lateral undulation and the so-called "concertina" mode, wherein the reptile stabilises itself with tight-coiled gripping and then reaches upward. Besides the slimmer profile many boast, some arboreally inclined snakes can, one way or another, manipulate their scales into a "ventro-lateral keel" for better purchase. The relative roughness of a climbing surface, unsurprisingly, makes a difference when it comes to how easily a snake can ascend it. Bird nests built in trees with smoother bark are less likely to be pillaged by rat snakes.
Part of the efficacy of the specialised fences that Rattlesnake Solutions designed stems from rattlers’ less-than-impressive performance when it comes to scaling smooth (and tall) vertical surfaces. As Hughes wrote in his blogpost, “Rattlesnakes can climb if there are sufficient rough surfaces to grip, which excludes your block wall or rattlesnake fence (if installed properly).”
Incidentally, as Steen addresses in Secrets of Snakes, the venomous North American serpent probably most entangled in dropping-out-of-trees mythology – much more so than rattlers – is the cottonmouth, or water moccasin, of the southeastern US. It’s not uncommon to hear stories about these burly, semiaquatic pit vipers – fond of swamps and bottomland forests – plunking into boats out of overhanging canopies.
While acknowledging that anything’s possible – and that cottonmouths do occasionally bask in trees, though, like rattlesnakes, they’re not all that well-engineered for climbing – Steen stresses such an admittedly hair-raising event is on the unlikely side of the spectrum.
Some of the folklore, he points out, may ultimately derive from mistaken identity: A non-venomous snake commonly confused with the cottonmouth and sharing its habitat, the brown watersnake, readily climbs waterside shrubbery and will promptly plop into the water when spooked – maybe, every once in awhile, unwittingly falling into a boat sliding underneath the branches.
Header image: Tom Sykes
Animal Behaviour
Animal Behaviour
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