Northern Pacific Rattlesnake: Species of the Week

I had originally planned to post on another species this week.  In fact, I have a backlog of species that have been inspiring and distracting me.  But rattlesnakes have a way of making themselves heard above the din of all else.  So this week goes to them (I also continue to face the challenge of working mostly from my remote office with a very slow dial-up connection and have more off-line information on rattlesnakes than the other critters).

The Northern Pacific Rattlesnake (Crotalus oreganus oreganus) ranges from south-central British Columbia into the Sierra Nevadas, where it roams as high as 11,000 feet.  In cold winter areas like ours, the snakes overwinter in dens and become active above ground during warm months.

Northern Pacific Rattlesnake heading up garden path

I anticipated running into rattlesnakes earlier this summer, but I didn’t see my first until August 5, and then I saw three.  Several days later, I saw a huge one slither out from under the tomatoes in my garden.

Once again, I ran for the camera. Then I called Jerry, and we debated some ideas that could get us laughed out of this county of ranchers and hunters.

Should we let it stay?  Perhaps it’s zeroing in on the gopher burrowing through my cipollinis. Or maybe it’s hunting down the vole or packrat raiding the strawberries.  Wouldn’t it be wonderful to let a natural predator take care of small mammal pests.  No more missing fruits or plants.  No more grim death traps.   How convenient.

Rattlesnake in clover

We kept an eye on the snake moving through the clover towards cover.  It was old and pretty mellow.  For a moment, I had a vision of peaceful co-existence.  If only we could keep track of its whereabouts.

I considered where the snake first appeared.   If I’d entered the garden a minute earlier to pick beans, I might have stepped on it. That’s my greatest fear.  It’d be hard to see a snake through the lush plant growth.  I like snakes, but I don’t want to startle a poisonous one into biting.  Hoping to inject some reason into my reptile-loving brain, I conjured images of searing pain, driving for an hour to get to the hospital, necrotizing flesh, weeks of recovery.

We weighed our options.  Meanwhile, the snake took refuge from us under some eggplants.   It hadn’t yet rattled or coiled.  I snapped a few more pictures.  I particularly wanted one of its tongue flicking out, but kept missing.  I sensed Jerry’s impatience to get back to work.

Rattlesnake under eggplants

Alright, we agreed, we’ll take it out.  This option had it’s risks.  Trying to handle, capture, photograph, or kill a rattlesnake increases the likelihood of a strike.  Not surprisingly, the risk increases when people are drinking alcohol. We looked forward to a beer each that evening but hadn’t had any yet.

Jerry fetched the snake tongs.  I ordered them last year, making sure to get the kind that are least likely to damage internal organs.  This was our first opportunity to try them out.  In one deft move, Jerry grabbed the snake and put it in a small garbage pail.   Only on capture did the snake rattle.  It never tried to strike.  Jerry secured the lid and carted the pail, with the snake still rattling inside, off to the canyon rim for release.

That night, I opened one of my favorite coffee table books:  Rattlesnake: Portrait of a Predator by Manny Rubio.  I read the section on how rattlesnakes hunt and eat.

A rattlesnake uses two strategies to capture prey:  strike and hang-on or strike and release.  It tends to use the first with lizards, insects and frogs and the second with small mammals, perhaps because they can bite back.   A snake stakes out regular pathways used by small mammals.  When one happens by, it strikes, injects toxins and releases.  An envenomated mouse or packrat wanders for a bit, collapses and then dies.

With its tongue and Jacobson’s organ (a smell and taste apparatus in the roof of the mouth), the rattlesnake can track the chemicals it injected into its prey for at least a hundred feet.  It finds the carcass and probes.  It uses its tongue, Jacobson’s organ and nostrils to make sure the prey is dead.  It also detects odors coming out of the mouth to find the head.  Swallowing an animal whole is most efficient head first since appendages fold backward.  Venom begins the digestive process; other chemicals get to work once the prey is swallowed.  Pepsin and hydrochloric acid break down all but hair, feathers, and maybe a few teeth.

I reconsider my fantasy (hard to understand, I admit, if you’re not into snakes) of having this amazing predator patrol my garden.  If I could somehow get around that nagging problem of dangerous bites, how much would the snake actually eat?  Not that much, apparently.  A medium-sized rattlesnake eats in one year what a coyote eats in a single meal.   That might add up to about six rodents a year.  I might need several rattlesnakes to clear out pests.  And then they’d spend more time under the tomatoes digesting and drinking water from my drip irrigation than eating gophers or voles.

Back to gopher traps for us.

Further reading:

If you think me far too smug about the thril of finding rattlesnakes and want to know what creature does make me shiver with irrational fear, check out my essay ,”A Nature Lover’s Phobia” published online in Fringe Magazine.

Cross-posted as Biodiversions at The Clade.