Tunnels

This week, I began my integrated pest management rotation in earnest.  Right now, the focus is on gopher trapping.  The ambivalence I felt toward killing furry creatures before I began the rotation remains, but is now manifested in mixed emotions as I walk the fields setting and checking my traps. 

Gophers are a major predator on the farm, destroying plants primarily by eating their root systems from underground.  The basic approach to gopher trapping is to find areas of recent activity, set traps in the area, and return in 1-2 days to check the traps. 

Step 1: Find areas of recent activity.  Gophers live underground in an interconnected series of tunnels.  When digging their underground tunnels, the dirt they are pushing out of the way has to go somewhere, so they push it to the surface, creating a mound of fresh soil.  I think the freshly turned soil looks like coffee grounds.  Damp soil, which is darker in color than the surrounding ground, indicates a fresh mound.  Older mounds have dry soil.  Of course, gophers aren't the only burrowing creatures on our farm, so I also have to distinguish between mole and ground squirrel activity.  Ground squirrels don't create mounds--they just leave big holes in the ground marking the entrance to their burrows.  Moles do create mounds, but they tend to be volcano-shaped, unlike gopher tunnels, which are horseshoe-shaped.  So I walk the fields somewhat randomly, looking for horseshoe-shaped mounds of damp coffee grounds.

Horseshoe-shaped gopher mound

Step 2: Set traps.  Once I find a fresh gopher mound, the first step is to find the tunnel/s associated with the mound.  This requires probing the ground around the mound with a plastic stake, feeling for an area of intial resistance as the probe penetrates soil, then no resistance as the probe enters a tunnel.  Once I think I've found the tunnel, I slip a hori hori knife along the probe and create a pocket for my hand to enter the tunnel, pulling the knife out as I slide my hand in. 

Hori hori knife

Once my hand is in, I feel around to determine which direction the tunnel is heading in.  Often, there are 2-3 tunnels that converge into the pocket I'm in, and I can set a trap in each one.  The next step is excavation, the most time-consuming part of the process.  The traps we use are larger than the tunnel entrances for the most part, which means I have to widen and deepen the tunnel entrance to fit a trap inside.  Once I have a big enough hole, I set the trap's trigger mechanism above the ground.  We use Victor gopher traps. 

Victor gopher trap



Trap set in underground tunnel

Once the trap is set, I carefully place it at the entrance to the tunnel, then backfill the area I excavated with dirt.  To make sure I can find the trap the next day, I place a stake with a bright orange flag right next to the area.  The stakes are tied to the underground trap, making it easy to pull the trap out of the ground to see if you've caught a gopher.



Flag marking a set trap

I find steps 1 and 2 to be rather enjoyable.  I get to work on my own, exploring the farm, keeping my eyes open for signs of gopher acitivty.  I feel connected to what's happening in the fields.  It's satisfying to identify a mound, successfully probe for a tunnel, and excavate an area to set a trap.  If I don't think about what the traps are for (killing gophers), setting traps is a pleasant way to spend a day.  It's step 3 where the mixed emotions come in.

Step 3: Check the traps.  On Friday, I set 8 or so traps, in several areas of our main field.  On Saturday, I looked for my orange flags and checked each for a gopher.  As I grabbed the string and began pulling my first trap to the surface, half of me hoped the trap would be empty, while the other half wanted to be successful with this new task.  Much to my relief, the first trap was empty.  So was the second.  And the third.  And the fourth.  At this point, while relieved to have not killed anything, I was getting worried that I was doing something wrong.  As I pulled my fifth trap out of the ground, I fully expected it to be empty, too.  So as the trap reached the surface, I was startled to find a gopher on the end of the line.  My heart sunk as I jumped back at the sight of the lifeless gopher.  I never thought success could be so disappointing. 

My first day of trapping yielded two gophers, each of which was buried in its own tunnel.  When I reported my results to my supervisor, I was congratulated.  My heart soared momentarily--I had done my job well and been successful.  Yet that success meant the loss of a life, and I didn't feel comfortable celebrating that.