June of 1961 found Cal State Long Beach entomologist, Dr. Elbert L. Sleeper collecting insects on the western slopes of the Baja Peninsula’s tallest mountain range – the Sierra San Pedro Mártir. The definition of contrast, the sierra’s occasionally snow-covered peaks tower some 3000m (10,000ft) above foggy coastal sage scrub to the west, and wind-swept desert dunes to the east. Dr. Sleeper was in the company of a 35 year old Andrew Meling – vaquero on the 10,000 acre cattle ranch bearing his family’s name – who was lucky enough to call the Sierra San Pedro Mártir his birthplace. Andrew had noted the presence of medium-size frogs at the end of a remote valley and an interested Dr. Sleeper, who’d collect herpetological specimens on occasion, made the strenuous hike to the mountain meadow.
On June 12th he managed to collect two of the critters in deep pot holes of a granite-lined stream. These frogs would eventually make their way back to Cal State Long Beach and into the hands of Dr. Richard B. Loomis, and then those of Dr. Robert Stebbins and Dr. Richard Zweifel who confirmed the frogs as a nearly 500km southern range extension for the Foothill Yellow-Legged Frog (Rana boylii).
And virtually as fast as they were found, they vanished. Dr. Sleepers original specimens were lost in shipping, and subsequent trips to find Rana boylii in the Sierra San Pedro Mártir have come up empty handed. While potential explanations ranging from extirpation to a specimen/locality mix-up have been documented in the scientific literature and muttered in private, we wanted to see for ourselves.
By the time we had pulled into camp it was too late to set off, but a San Diego Nightsnake (Hypsiglena ochrorhynca klauberi) made an appearance near the campsite.
We awoke the next morning and started our hike through some of the most beautiful country that México has to offer — boulder strewn hillsides covered in manzanita, sprinkled with pines and punctuated by expansive dry meadows.
Halfway into the hike we had arrived at the target arroyo which, to our surprise, was flush with life. One of our secondary target species, the endemic San Pedro Martír Garter Snake (Thamnophis elegans hueyi), made an appearance. Like with Rana boylii, these mountains represents the southwestern outpost for these wide-ranging garters, with the closest relative some 350km to the north in the San Bernadino Mountains of Southern California.
Southern Alligator lizards (Elgaria multicarinata), Gilbert's Skinks (Plestiodon gilberti), and Western Skinks (Plestiodon skiltonianus) scurried through leaf-litter while Southern Sagebrush Lizards (Sceloporus vandenburgianus) and Western Fence Lizards (Sceloporus occidentalis) darted across fallen logs and boulders. The waters' edge was active with Pacific Treefrogs (Pseudacris regilla), California Treefrogs (Pseudacris cadaverina), and California Toads (Bufo boreas halophilus) in the streamside vegetation and rocks with Two-Striped Garter Snakes (Thamnophis hammondii) in pursuit. Even a Garden Slender Slamander (Batrachoseps major) turned up, but despite careful searching through plunge pools and potholes — Rana boylii was no where to be seen.
Empty handed in our search for R. boylii and without a "Plan B Arroyo", we took aim at our third target, and one of the Sierra San Pedro Martír's most secretive gems: the Baja Mountain Kingsnake (Lampropeltis zonata agalma). Only five specimens from this mountain range have made their way into scientific collections since the species was descibed in 1923, however interest from the pet-trade has driven U.S. collectors to relentlessly pursue snakes at this locality for decades — largely unsuccessfully. With the exception of some isolated and incidental encounters, the majority of L. zonata agalma observations in "The Martír" have been made by Paul Lynum, and a handful of other collectors under his tutleage. Before leaving, Paul shared a tip that we hoped would prove useful: "find the Gilbert's Skinks, and you'll find the agalma."
While Paul's methodical efforts had produced dozens of observations along the dry slopes of the sierra — in what could be considered marginal habitat — our search for Rana boylii had landed us in prime habitat for mountain kingsnakes.
After moving up from the arroyo bottom, it wasn't long before a Gilbert's Skink (Plestiodon gilberti) appeared under a rock, followed just minutes later by the brilliant pattern of an adult Lampropeltis zonata agalma crawling along the base of a boulder outcrop.
Less than a half-hour later, a juvenile Baja Mountain kingsnake was flipped beneath a rock just up-the slope from the creek.
Content with our consolation finds, the team began the hike back up the arroyo and through the hills to camp — a return trip that wouldn't conclude until the early morning hours.
The trip westward out of the Sierra San Pedro Martír towards the coast produced a single Long-nosed Snake (Rhinocheilus lecontei) and much lighter Southern Pacific Rattlesnake (Crotlaus helleri). Looking to leverage their newfound Lampropeltis-luck, the team set sights on another king: the Todos Santos Island Kingsnake (Lampropeltis herrerae).
Closely related to L. z. agalma from the Sierra San Pedro Martír, the species represents a relictual population whose existence is thought to be linked to the absence of competing species like Lampropeltis getula and Pituophis catenifer on its island home. Like the Baja Mountain Kingsnake, the Isla Todos Santos Kingsnake's commercial value has placed it under heavy pressure from poachers, and illegal collecting over the last few decades — still evidenced to this day by rusted traps and damaged rocks — has resulted in tightly controled access to the island.
Almost as soon as we landed, we were met by two approaching boats with authorities from SEMARNAT and CONANP. After a quick review of our permits and assurances we would not be disturbing any nesting birds, we were off to try our luck in the hills.