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Patch-nosed encounter at Mission Trails Regional Park

Posted: August 18th, 2017 | Columns, Featured, Mission Trails - Trail Guide | No Comments

By Audrey F. Baker

For many, one of Mission Trails Regional Park’s must-see sights is Snake Rock. Head north on Father Junipero Serra Trail from the Visitor Center toward Old Mission Dam.

About the time you settle into your gait, you’ll see it on the left. Wind, sun and water erosion have carved the distinctive figure of a rattlesnake, replete with heavy-body and triangular shaped head. Perhaps nature sculpted it to remind us of her mysteries and creativity. Here variety reigns, snakes included!

The Western Patch-nosed Snake (Photo by George Varga)

Ask trail guide George Varga. He’s got a snake trail tale for the telling.

While patrolling Barker Way Trail about mid-point to Cowles Mountain’s summit with Marty Fink and Matt Franco, the threesome happened upon a surprising sight — a snake writhing on flat ground.

The thin-bodied, three-foot-long striped reptile had smooth scales and large eyes.

Immersed in flailing activity, its movements were fast and captivating.

Although a volunteer at the park since 1995, Varga had never seen this species of snake. Here was an opportunity to not only view a lesser-seen animal but also to observe remarkable behavior. The threesome remained at a safe distance, avoiding casting a shadow over the animal to avoid alerting it to their presence.

Out came their cameras to record the action. Documenting with photos, and video later, allowed accurate identification and interpretation of the snake’s activities.

With no burrow evident, the squirming and twisting snake then transitioned into digging. It appeared to be bringing mouthfuls of dirt to the surface and spitting them out as it toiled.

Excavation was now fully underway. The progression from writhing to penetrating soil at a level where only a couple of inches of the snake’s body remaining above surface took only 13 minutes.

The next step was to identify the snake. Emails, consultations, postings on YouTube and iNaturalist led to authoritative identification and insight into the habits of the Western Patch-nosed Snake (Salvadora hexalepis).

Bradford D. Hollingsworth, Ph.D., curator of herpetology at the San Diego Natural History Museum, commented on the snake’s energetic excavation, suggesting the snake was digging out a nest to dine on reptile eggs or had located a whiptail lizard.

Greg Pauly, Ph.D., who holds the comparable position at National History Museum of Los Angeles County remarked that close examination of the video reveals while digging, the mouth is closed. The species uses its neck as a trowel to pull dirt out of a hole.

Here’s the skinny on this denizen of Mission Trails. Salvadora hexalepis is endemic to Southwestern parts of the U.S. (California, Arizona, New Mexico, Nevada, and Texas) and into Baja, Mexico. Relishing sandy soils and rocky terrains, it populates grassland and slopes of chaparral-laden mountains, burrowing in loose soil.

Attractively marked by a yellow to beige mid-dorsal stripe bordered by pale gray striping, its ventral side is whitish tinting to orange at the tail. The top of the head is gray. Its coloration provides excellent camouflage. Known to achieve up to 46 inches in length, most are 26–36 inches.

The animal is well equipped. Its famed “patch-nose” is a thick and enlarged rostral scale that curves back over the top of the snout. This specialized tool helps creates a well-functioning snout designed to loosen dirt. The Western Patch-nosed Snake uses its acute sense of smell to locate reptile eggs. This likely explains the above-ground writhing movement Varga and his friends observed.

Benefiting from alert round-pupiled eyes and the ability to move rapidly, the species is well served for hunting and protection. An opportunistic hunter, it climbs shrubs in pursuit of prey. Diet delights includes lizards, grasshoppers, small mammals, possibly small snakes, nestling birds, and amphibians. To avoid summer heat intensity, these daytime hunters are crepuscular (active during twilight).

Few details of its abundance and life history are known. It possibly is preyed upon by raptors, roadrunners, diurnal mammalian carnivores, king snakes and other snakes.

As a nonvenomous colubrid snake, the Western Patch-nosed Snake’s venom is not dangerous to most humans. When cornered, it will defend itself. The species puffs up and strikes. It’s all part of our rich bio-diverse community. Respect nature and keep it wild!

—Audrey F. Baker is a trail guide at Mission Trails Regional Park. Check the MTRP events calendar published here or at mtrp.org or call 619-668-3281 for more information on the park’s free trail guide-led nature walks and opportunities to learn more about natural Southern California. Special walks can be arranged for any club, group, business or school by contacting Ranger Chris Axtmann at 619-668-2746 or at caxtmann@mtrp.org.

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