Plants That Attack, and a Well-Traveled Rat

S. Amanda Caudill, a doctoral student at the University of Rhode Island, writes from Costa Rica, where she is assessing mammal diversity on coffee farms.

For Jicotea, we divide the site into two halves to check and bait the traps. This means hiking for about four hours each morning.

This site is like an obstacle course. Our grid encompasses several farms; so we go over, under and in between about 20 barbed-wire fences during our morning rounds. We have gotten quite good at maneuvering through the spiked wires. Another danger on this site is the pejibaye trees. They are a palm fruit and very tasty, but the needles on the trees are painful. You really have to watch where you put your hands.

The one land use that we all dread on this site is the sugar cane. Right now, it is about seven feet tall and will not be cut until March. I am told that it begins to bend, cross and weave with the adjacent stalks. I am not sure how we will check the traps when that happens, because I, for one, am not keen on army-crawling through that. The sugar cane stalks are as sharp as razor blades, and it is hot under there. We wear long sleeves and try to protect our faces and hands as we push our way through the stalks, but we inevitably end up with tiny cuts by the time we get to the other side.

There are also dogs, horses and cows to maneuver around as we make our way through the grid checking all the traps. One dog in particular is quite scary. His name is Mancha, which means “spot.” Every day we walk by him, hugging the edge of the pathway to put as much distance as possible between us and the length of his leash. He lunges at us, barking and growling, and we pray that the leash will hold. One day, Mancha pulled so hard that his collar slipped right off his neck. As the dog came tearing toward my field assistants, one of them screamed and the other froze in place, but Mancha just trotted between them to a bush and relieved himself.

At Jicotea, we set up the minigrids in sun coffee, shade coffee and forest. Our capture rates in general were much lower than in Round 1, with a trap success rate of 1.47 percent, compared with 2.53 percent in the first round. Here at Jicotea, as at the Catie site, the minigrids did not add much data. There were three individual mammals captured in the minigrids – one in the sun coffee, one in the shade coffee and one in the forest. We did, however, add two new species to the list for this site: roof rat (Rattus rattus) and gray four-eyed opossum (Philander opossum).

A week of chilly rain left us with mice that were weak and wobbly when we let them out of the traps. We tried to warm them up and offer them something to eat to regain their strength. One little dusky rice rat took some bites out of the banana that a farmer, Leo, gave him.

A female juvenile dusky rice rat has joined us on our journey through Jicotea. We first met the small traveler, who weighs less than 30 grams, in the pasture habitat. Most of the home ranges for these small mammals are not well known, but are thought to be less than 50 meters. This little one, named Gulliver by my field assistant Megan, traveled more than 100 meters in one night from pasture to sun coffee, then again more than 100 meters from sun coffee to sugar cane in two days, then in one night 50 meters to another sugar cane point, and back again another 50 meters. I’ll be interested to see if we capture her again in our next round of sampling and where her travels will take her.