Snakes vs Rats in a California Garden
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Q. I have rats eating my plums and would love to have snakes in my garden that would eat the rats. Many snakes are indigenous to my area (Rattlesnakes, Garters, Gopher snakes…); and I have many wonderful blue belly lizards in my garden—but unfortunately, no snakes. Would it be a good or bad idea to buy a garter or gopher snake from a pet shop and let it go in the back yard? I'm only talking about snakes that are already indigenous to my local area. Thanks for any information you can give me.
---Mark in Sacramento
I actually have to thank Mark, because his question led to my finding an amazing web site: "California Herps dot com: A guide to the amphibians and reptiles of California". It's the project not of a University or doctored researcher, but a self-described 'herp nerd' named Gary Nafis, and it answered all my questions about this topic and then some.
The first question, of course, is "Do any California snakes even eat rats?"
Turns out that it's a very short list. Garter snakes, for instance, are way too small. Some snakes native to Mark's Northern California location are big enough—like the kingsnake, gopher snake, rubber boa, and yellow bellied and striped racers; and Gary's site lists 'small rodents' as being in the diet of those specific snakes…
But rats are not 'small'. My hunch was that they'd be the last prey even a big snake would go after. And Gary agrees, saying, "in the world of California reptiles, wild adult rats are too big and fierce to be killed by anything but the strike of a venomous rattlesnake."
I know that fierceness personally. I cornered a rat in my house years ago, freaked out (my kids were still babies), and essentially killed it with my bare hands, pushing it hard against a brick woodstove support and just holding on until it stopped breathing. I don't recommend anyone else try this; I shook for days afterwards. They are almost impossibly muscular and powerful for their size.
And that's why rats are specifically listed as prey for only one snake indigenous to Northern California: The aforementioned rattlesnake.
I had thought that perhaps the 'gopher snake' would qualify. Gophers are about the same size as rats, and these big snakes can reach nine feet in length. But again, there's that legendary strength and fierceness in between the snake and its ratty meal—and California has lots of less-feisty gophers for the snakes to prey on. And it's a good thing they do prey on their namesake—gophers are serious farm and garden pests in the West. (And, as the movie Caddyshack taught us, golf courses as well.)
Gopher troubles can be quite a shock to a newcomer from back East. When my friend Jeff Cox moved from rural Pennsylvania to the California wine country, he resorted to keeping a burlap sack and a device called a 'snake git' in his car. When he would find a big gopher snake sunning itself on a highway, he would try and 'collect' it to release in his gopher-plagued garden.
Was this legal? Probably not. It might be legal to 'collect' such a wild snake if you have a specific type of fishing license, but it's definitely illegal to then release it, explains 'herp nerd' Gary—who really knows these regulations, although be wisely does not want to be considered the last word on any legal advice.
Anyway, Gary first wanted to stress that it is obviously "unethical and illegal to release non-native reptiles or amphibians."
('Obvious' is right. Florida is flooded with exotic creatures like South American boa constrictors and Burmese pythons that were foolishly released into the wild.)
Gary continues that the release of native species is also "unethical and illegal", especially when you add in our listener's 'pet store' kicker. My first reaction to Mark's email was that you should never release anything you got from a pet store into the wild; and The California Department of Fish and Wildlife "Native Reptile Captive Propagation Laws and Regulations" specifically forbids such releases, whether the snake was bred in captivity or captured in the wild.
So; no plums for Mark?
Actually, we hope to make Mark plum happy—just not with an introduced snake. If you see rats anywhere in your landscape, you must eradicate them quickly and directly. You don't want to introduce a snake in the hope that it'll get around to the rats after it eats all the easier prey. A much better response would be to deploy several of the relatively new battery-powered rat traps that electrocute their prey. The bait is contained inside the box-shaped trap, so there's much less chance of it hurting a non-target creature like a bird than an old-school snap trap.
And whatever you do, don't use rat poison! A snake or raptor could eat the poisoned rat and then you'd be overrun with all the vermin they would have controlled during their lifetime; hundreds—maybe thousands—of mice and rats.
Now—let's talk about Mark's "blue bellied lizards", which DO have distinctive blue bellies but are more commonly known as fence post lizards, because they like to climb up high to sun themselves. They would be the first prey of a big snake, which would be tragic as they are voracious predators of mosquitoes and grasshoppers.
More importantly, when a tick carrying Lyme disease feeds on a fence post lizard, the Lyme disease inside the tick becomes deactivated. That's right: If that tick then bites you, you won't get sick. Researchers have even found a lower incidence of Lyme disease in areas with lots of these cute little lizards!
(Citation: Lane, R. S.; Mun, J.; Eisen, L.; Eisen, R. J. (2006). "Refractoriness of the Western Fence Lizard (Sceloporus occidentalis) to the Lyme Disease Group Spirochete Borrelia bissettii". Journal of Parasitology. 92 (4): 691–696. PMID 16995383. doi: 10.1645/GE-738R1.1.; from https://en.wikipedia.org/wiki/Western_fence_lizard.)