I Saw A Tapir And Almost Baked Some Hermit Crabs

We just left El Campanario, a biological field station on the Osa Peninsula, and, while I can’t wait to get back to internet and call all my loved ones, I will miss the ocean.

We arrived at El Campanario a week ago for, surprise surprise, more ecological research! We were all surprised, though, at the sheer beauty of the place. Our TAs had been describing the place FSP used to go – a station called Sirena where the building was practically falling down and it was too hot and muggy to sleep. Instead, we had a beach landing at an Oceanside paradise where Nancy, the owner, says past students even come to honeymoon. It’s pretty understandable. El Campanario is the total opposite of Cuerici with a bathwater ocean and a humid rainforest, and I was honestly relieved. As soon as we unpacked, we all ran into the ocean without looking back, practically stripping off clothes as we went. We needed a break from the cold, though it makes me feel guilty thinking of those poor students back in Hanover. We talked and swayed in the waves until dinner, watching spider monkeys jump between trees on the shore.

It’s impossible to describe the beauty of any of the places we’ve been to, but Campanario has been, by far, my favorite.

The next day, we went on a five-hour hike (though it was supposed to be only two hours, I say only slightly bitterly) with Freynar, the colorful nature guide who has a special knack for finding mannikins in the forest. Blue-crowned and red-capped mannikins, just two of the bird species that occupy the forest around El Campanario, are known for the males’ cooperative mating dances to attract females. Also on this walk, some of the students ate termites (apparently they taste like celery) and had their faces painted with the refuse of a leaf-cutter ant colony, which apparently is an excellent exfoliant. We also climbed into the trunk of a tree. I felt like one of the lost boys in Peter Pan squeezing inside (they live in a hollowed-out tree), and, while I was down there, a bat flew in my face from its perch in the wooden eaves of the tree.

We spent the rest of the day working on our manuscripts from our last project (thermal rewards in Cuerici) and planning our new research ideas. After many shifted groups and random thoughts, I finally landed on studying the hermit crabs that occupy the beach in El Campanario. According to Nancy, the larger crabs come out on the beach at night, while the smaller ones stayed on the beach during the day. So we decided to investigate why that might be. After a week of brainstorming, data collection, and statistics, we presented our findings at the symposium last night. Here’s what we know: there are more crabs in the leaf litter that lines the beach than on the sand, both at night and during the day (in our litter plots we would sometimes count 100 individuals, while beach plots barely yielded 20). We also found increasing size in the order: sand during the day, litter during the day, litter at night, and sand at night (with the largest average size of crabs). So why do crabs have this spatial and temporal distribution? We conducted trials in an arena to test competition between size classes (there wasn’t any), and thermoregulation (smaller crabs were generally hotter than bigger ones, but we had some scary episodes with the big ones when we thought we’d killed them by baking them on the sand, so we thought they had a much worse reaction to heat). So we basically ended up with more questions than answers about the mysterious hermit crab. One theory is that the crabs distribute themselves this way because of the temperature on the beach, and, because the small hermit crabs can’t travel as far, they tend to stay closer to water sources. My pet hypothesis as to why they’re distributed this way is that the big ones can accomplish a greater distance migration (from sand to forest and back again in a day) just because they’re bigger, and the little ones have yet to gain the physical capacity to make it this far. Our ideas are a bit up in the air right now, but it was a fascinating study. One takeaway is to realize how important border habitats are, and that beach development can negatively affect species like terrestrial hermit crabs.

In between long periods of work this week, we also saw and did some other amazing things. Dotted between days, we watched tapirs clamber through our camp, looking for sugar cane. We crushed our own sugar cane to make sugar cane juice, which we drank with starfruit and guaro, a local sugar cane alcohol. Nancy taught me to look for the spider eyeshine reflected from my headlamp when walking the ground, a practice that I am simultaneously fascinated and terrified by. We swam out to a buoy and gossiped about blissfully non-science-y things. We had a bonfire by the seaside and roasted marshmallows. And so I was sad to leave when the time finally came. But I’m excited for the next adventure, new and improved – with WiFi!