Sebastian Scofield: May 2011 Archives

Last field day

By
Sebastian Scofield
on May 25, 2011 9:41 PM | | Comments (1)
Today was our final day of work in the field. I collected the last nine of fifteen pitfall traps I had placed. I'll bring the collected specimens back to Dallas with us, and identify them once we're back in the lab. Then I'll identify all the individual ants down to species, and calculate species diversity and abundance in our three habitat sites.

We took a hike to a nearby original forest called Orlando's, where we found two species of live Odontomachus ants, many leafcutter ants, and a raiding column of Eciton burchellii army ants driving across the forest floor, devouring everything in its path. Several of us momentarily had ants in our pants, before we noticed and hastily danced around, brushing them off. We observed the worker army ants using their own bodies to fill potholes in the road and make bridges for their comrades to travel over. Their coordination and teamwork were inspiring to us all.

Tomorrow Austin, Christian and I plan to set out for the far side of Arenal volcano, led by our intrepid guide Oscar. We hope to see many species of birds and ants. In particular, I hope to find bala, or bullet ants, Paraponera clavata. These ants are over an inch long, and have the most painful sting of any insect. The bullet ant is called by the locals "Hormiga Veinticuatro" or "24 hour ant", from the 24 hours of agony that follow a stinging. On the Schmidt Sting Pain Index, which only goes up to a 4, bullet ant stings are a 4+. Perhaps we shall find these fierce ants in the jungles of El Silencio.

-Sebastian

Trap-jaw ants

By
Sebastian Scofield
on May 24, 2011 10:51 PM | | Comments (2)
Today I placed the last nine pitfall traps, and collected the twelve traps I had placed earlier. The ant diversity here is incredible. The traps caught three Odontomachus bauri workers, a beautiful black trap-jaw ant that is a generalist predator on leaf-litter insects. Its mandibles, used to capture prey, can close at speeds of 145 miles per hour, giving these ants the fastest self-powered predatory strike in the animal kingdom. The average duration of a strike is a mere 0.13 milliseconds, or 2,300 times faster than the blink of an eye.

I also was able to capture a single worker of large, very fast and agile black ant species that I have so far been unable to identify. As John mentioned, it seems to be mimicking wasps, which is not a behavior I have ever heard of. Myrmecomorphy, or the mimicry of ants by other species, is common in wasps; but as far as I know, the mimicry of wasps by ants is not well-documented. Further research will be needed once we return to Dallas to determine the classification of this ant.

All in all, it was a great day of field work. I love it out here. I think I could do this kind of work the rest of my life. Tomorrow's our last day to collect data. I'm looking forward to spending another day with these amazing ants.

-Sebastian

Trapping the beasts

By
Sebastian Scofield
on May 23, 2011 11:22 PM | | Comments (1)
Yesterday was our first day of real field work. We set up a 30m transect in an original forest habitat. I flagged the line every 5m and set up a pitfall trap for ant collection by each flag. Our pitfall traps are plastic cups set into the ground with the opening level with the surface of the soil. A worker ant will be out foraging, minding its own business, when suddenly it will slip on the smooth plastic edge of the cup, and fall straight to the bottom. Waiting for it in the bottom of the trap is a layer of isopropyl alcohol that both kills and preserves the specimens.

I bought supplies for the pitfall trap at the nearby "Super Kike," a local grocery store. I got several containers of isopropyl alcohol and package of plastic cups to make the traps. It was pretty much the sketchest purchase anyone's ever made. The cashier looked at me funny and asked, "Is that all?" When I said it was, she probably just thought to herself "Americano loco..." and left it at that.
Ant Alcohol.jpg

Today we continued our setup of collection points. I laid down two 10m transects in two different monoculture teak forests, with pitfall traps every 5m. I also started tuna baiting in the teak forest and collected the ants that were foraging on six different tuna baits. I'm not sure whether pitfall trapping and baiting will be sufficient to capture specimens of all the cryptic ant species and specialist predators that are found here, so hopefully we'll be able to use Berlese funnels to extract ants from leaf-litter samples collected from our different habitat sites.

After a successful day in the field, it was satisfying to reflect on it while eating a delectable Costa Rican dinner and enjoying the company of my fellow researchers. I'm looking forward to getting a good night's sleep tonight, and waking up tomorrow and confronting the challenges of the new day.

-Sebastian
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First day among the ants

By
Sebastian Scofield
on May 21, 2011 10:04 PM | | Comments (1)
After a long day, I'm relaxing in the Volcano cabin with Austin and Christian, listening to the deafening sound of a torrential tropical downpour. We can barely hear each other talk over the noise. Outside, lightning flashes and thunder rolls, but inside we're safe and dry. We've lost power once so far, but it's back now.

Just this morning it was dry and sunny. We started the day by taking an orientation walk of our project site to familiarize ourselves with the layout of the land and the different habitat types we're going to be surveying. The local ant fauna is diverse and fascinating. One of the most interesting species is the leafcutter ant, Atta cephalotes. These ants harvest leaves from trees, but they don't eat them. Instead, they carry them back to their vast underground nests, where they chew and process the leaves, turning them into substrate for intricate fungal gardens. The fungi serve as their only food source. Each colony can use as much vegetation in a single day as a full-grown cow, so they need to collect a lot of leaves. We watched green tendrils snake across the forest floor, the highways of ants each carrying a small piece of leaf overhead. Other genera have been identified as well, such as Ectatomma, Solenopsis, and a beautiful Aphaenogaster species.

We worked on project protocol today, and decided to set up a transect of pitfall traps tomorrow morning to begin our specimen collection. We plan on doing samples of ground-dwelling ants in each of the three forest habitat types (original, natural reforest, and monoculture) to find and compare species diversity and abundance.

But it's late right now, the 5:30 wakeup call is going to come early, and our roof just sprang a leak. It's time to get some sleep: we have a big day ahead of us. 

-Sebastian

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