Wednesday, January 20, 2010

Gopher Bashin' or Caddyshack Redux

Which is it?  We are inundated by Gophers, a problem that we take very seriously around here.  The soils at Lynmar Estate are part of the bigger picture that make growin' Pinot Noir so good.  They are primarily sandy loams.  Well, just as it sounds, this makes for ideal digging, burrowing and tunneling.  Combine that fact with overarching sub-tropical climate and drip irrigation, high density of juicy vine roots, and you have some pretty happy Gophers.

I'm not stopping there...  If you've ever had the chance to BBQ over grapevine, you know that it can impart a sweet, caramelized finish to the flavor of your favorite cut of meat.  I would imagine that cruising around in the dirt, the chance encounter with a grapevine root would be pretty enticing.  Well you know it and so do I, Grapevines produce a damn fine beverage.  In the summer around here it gets pretty dry (something I'll elaborate on later when I write about climate and microclimates).  We have to keep the vines happy when the roots have started to deplete the moisture in the soils, and we can.  Most vines these days are set up with drip irrigation (so many different types), and we can meter the water out in exacting amounts (a mathematical equation can determine this based on daily weather patterns, watch for that entry later, also).

Where am I going with all this?  Although the sap from the vines is not directly tapped for wine production, it does translocate the carbohydrates to the different parts of the vine, so essentially it ends up in our glass, just via a nice little fruity morsel.  Gophers can appreciate this, too.  In fact they rely upon it.  The water from the drip system is picked up by the vines, the gophers eat the roots and absorb the moisture, or make incisions in the trunk of the vines and lick at the exudes from the bleeding vines.  In most cases this will lead to reduced production.  In a new vineyard with vines less than an inch in diameter, it often times results in death.  You can be cruising along the rows and you'll occasionally see a vine that for no other apparent reason has begun to dry up and get crispy.  I've seen enough of these to know exactly what that looks like, from very far away.  And when I see them, without fail, I can grab the trunk and pull the entire trunk, sans roots, straight out of the ground and there, just below ground level will be a gnawed section of the vine that went straight through the small, fragile vine.  Killing it.  So we must defend ourselves (read my previous entry where I discuss the economic decision making process).

In any other situation, I like Gophers for their natural action.  They are nature's deep tillers.  Mixing soils, breaking compaction and aerating anaerobic layers.  Burrowing as deep as 6 feet before coming back up and building their main dens around 3 feet deep (like the P-Trap under your sink, which prevents flooding of their main den (crafty)).  Then they create a series of tunnels, mainly around a foot deep for the purpose of feeding.  An adult male gopher can and will establish and defend a territory covering about 2000 square feet.  Gophers are also highly solitary and territorial.  They will fight each other to the death.  Males and females come together only for the purpose of mating (for a short window of time their tunnels will join, then after mating, they go back to their respective burrows and close off the connection.  Females will kick out the young when old enough to fend for themselves.  They will have to cover open ground to find a new territory, or an abandoned tunnel system.  This is one of the most vulnerable times, obviously.  Enter our favorite predator.
So far this winter we installed 14 owl boxes and 2 perches.  We have another 10 boxes and 10 more perches coming within the next two weeks (read: as soon as the weather breaks) (for more info about the boxes see .  Owls will be looking for nesting sights in March.  We are looking to knock the gophers out of commission and lower back below the economic threshold.  A sceptic was saying that all this investment in owl boxes will maintain current levels, at best, while all but rolling their eyes at the effort.  On one hand, I understand that owls are not burrowing creatures (with the exception of the burrowing owl), and the owl we are designed to host is the Barn Owl.  So they will get the ones that come up.  Gophers  do come up at night to move to new areas, or if they are forced out in a territory battle when tunnels and feeding zones come together.  They also poke themselves out to grab vegetation around their feeding holes.  So, I don't necessarily agree with is that they will have little impact on reducing our gopher pressure.  And here is why.

Owls mate for life, so when they come to nest, they come as a pair.  Occasionally a nest can support two fledgling Owls, but typically, out of two hatchlings, only one will survive.  By the estimates (based on pellet counts in and around boxed owl nesting sites, in the time it takes to raise that fledgling to juvenile status, each owl will account for ~1000 small vertebrates.  Granted, these won't all be gophers, as there are plenty of voles, moles, rats and other small vertebrates running around here, but where gophers exist, they will be in the mix.  So let's stay conservative and say that 33% of the diet will be gophers.  that means 1000 gophers per box per brood.  Then let's say we only get one brood per year, and not 2 as is often the case in high gopher population areas.  With 24 boxes, we are accounting for 24,000 dead gophers.  If a full sized adult gopher can dominate 2000 sq feet and an acre of vineyard is 43,560 sq feet, then, if all were full sized adult gophers, we would be looking at 22 gophers per acre.  On the assumption that not all gophers full fill the specs and only cover half as much space, then let's account for 44 gophers per acre.  One occupied Owl box with a successful fledgling in the family should have a significant impact on ~22 acres.  We have set ourselves up with 1 box for every 3 acres.  Hmm.  I think there will be an impact.

Let's now take a multi-pronged approach.  Lets get to trapping, as well.  The same contingency telling me that owls will have a marginal impact on reducing numbers also tells me that trapping is a maintenance activity at best.  Let's revisit a meeting I had with Gregg the Gopher Guy the other day.  First I should introduce you to Gregg the Gopher Guy.  He is one of those guys who not only knows about gophers because he thinks about them day and night and studies them 24/7 and relies on them for a living, and is quite proud of his success with that, but he is actually capable of thinking like a gopher.  I think this is critical.  So, one walk and talk with him through a gopher riddled vineyard and I observed him sniffing the air, stopping suddenly and pointing out a fresh gopher feeding hole.  The picture at the top is of what we call a lateral.  This is a large mound left behind because the gopher is on a mission and digging to go somewhere.  Very rare to find them actually open as gophers prefer and survive by living in a closed system (keeps the scent at home, not out wafting around the noses of foxes, skunks, coyotes and other digging carnivores, like Gregg the Gopher Guy).  But he was pointing out small very inconspicuous, freshly plugged up holes.  Do I believe he is actually smelling the gophers?  No (given the fact that when I showed him that same photo that I have at the top of the page he did the same thing), but I do think he knows what he is talking about.  He showed me what he calls the feeding zone, and showed me how to recognize the stunted growth in the cover crop that would indicate the full range of one individual gopher.  He showed me his modified traps and how and where to place them.  Look, I'm saying I learned a lot.  And I'm no slouch when it comes to trapping gophers, but I learned how to do it with probably less than half the effort.

I learned and believe, in the difference that his Gopher Goner trap makes in your success.  I learned that when the pessimist tries to tell me that trapping 127 gophers in one summer had no effect on the overall population on an 80 acre site, I believe that, and know that it didn't.  Because compared to successful trapping, that is a pathetic performance.  Gregg the Gopher Guy, using his methodology and equipment trapped 83 gophers on 6 acres in one 8 hour day.  Back to our math, if we are counting on 44 gophers per acre, he wiped out a third of the of the population in a single pass.  Check him out, he IS the Gopher Guy.  End of story.

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