Wild Neighbors: Serpents for Your Garden

By Joe Eaton
Tuesday April 12, 2011 - 08:56:00 PM
Sharp-tailed snake: a diet of slugs.
Steve Ryan (via Wikimedia Commons)
Sharp-tailed snake: a diet of slugs.

You have to admire a gardener who is proud of his snakes. 

The gardener in question is Al Kyte, a flycasting maven who has assembled a splendid collection of native California trees and shrubs on his Moraga property. The snakes are sharp-tailed snakes (Contia tenuis), shy and elusive reptiles that live under things; one has taken up residence in the roots of a dying apple tree in Kyte’s back yard. He appreciates them because they eat slugs. Maybe snails, although that’s an unsettled question; definitely slugs. 

I’ll admit that I’ve never seen a sharp-tailed snake, dead or alive. 

According to Robert Stebbins’ Field Guide to Western Reptiles and Amphibians, they’re 12 to 18 inches long, with reddish backs and black crossbands on the belly. The tip of the tail has a sharp spine whose function no one seems to have figured out. It may be an anti-predator defense, or an aid in burrowing. The mud snake of the Southeast has a similar structure which is believed by the more credulous to be a lethal sting, but no such folklore has attached itself to the sharptail. The sharptail’s evolutionary affinities are unclear, although recent genetic studies suggest a relationship to the ring-necked snake and (more distantly) the water snakes. 

Contia honors the geologist Joseph LeConte (as in LeConte Hall), a founding member of UC Berkeley’s faculty. Lecontia was preempted by a genus of beetle. How LeConte felt about all this is unknown. The snake was described in 1852, and it was only a hundred years later that herpetologists figured out how it made a living. Someone named Stickle noticed that the sharptail had uncommonly long teeth, and Richard Zweifel of UC’s Museum of Vertebrate Zoology suggested that was an adaptation for a diet of slugs. 

The stomach contents of dissected snakes have consisted solely of slugs. There is circumstantial evidence for the consumption of a slender salamander by a captive snake, but this has never been documented in nature. Some have speculated that the teeth would be equally suited for deshelling snails; again, this remains speculative. 

Better yet, sharp-tailed snakes seem to prefer invasive European slugs of the genus Arion, widespread garden pests. A native banana slug would be way too large for them. Experimental confirmation for the slug diet comes from Robert Weaver and Kenneth Kardong at Washington State University, who exposed captive sharptails to the smells of slugs, earthworms, distilled water, and Aqua Velva and counted the tongue-flicks elicited by each stimulus. Eau de slug was the clear favorite. (It’s hard to imagine what Aqua Velva would do to a snake’s olfactory system.) 

Much of this snake’s behavior remains obscure. Females lay eggs; a gravid female collected by Stebbins in Butte County produced a clutch of five. It looks as though no one has caught them at this in the wild. They can be oddly social: aggregations of up to forty have been documented, the largest discovered by a Joseph Colaci in a back yard and adjacent vacant lots in midtown Castro Valley in the 1950s. 

Their seasonal cycle appears keyed to rainfall. In California, sharptails become more active in March and April. They like damp conditions and are active at a lower temperature range (50 to 63 F) than most snakes. Stebbins has suggested that, as snakes go, sharptails have a salamander-like lifestyle. 

As recently as 2003, when the third edition of Stebbins’ field guide came out, all sharp-tailed snake populations were thought to belong to a single species. Then Chris Feldman and Richard Hoyer at the University of Nevada, Reno found divergent morphological and genetic patterns in coastal specimens. Their description of the new species Contia longicaudae was published last year. 

Longicaudae seems restricted to forested areas that experience a coastal effect, whiletenuis is more of an interior grassland and chaparral resident. Both species occur in the Bay Area: longicaudae in San Mateo and Santa Cruz counties, tenuis in Alameda, Contra Costa and Santa Clara. You can see photos of both at the California Herps site ( 

Unfortunately for those of us who are committed to integrative pest management, sharp-tailed snakes are not yet available at your local garden supply store. If one turns up in your yard, consider it a gift.