Monarchs abound at Las Cruces

OTS owns and operates three field stations- Palo Verde, La Selva and Las Cruces. After La Selva we spent a lovely week at Las Cruces, so I have now collected the trifecta of OTS field stations. Las Cruces is at a much higher elevation than La Selva (1400 m), and so is both cooler and less snake-filled. The station itself is surrounded by the Wilson Botanical Garden, one of the largest and most extensive botanical gardens in the world. The Wilsons started collecting plants for the garden in the 1960s, and OTS acquired the station in the later 70s. There are some thousands of different tropical plants here, each conveniently organized by group – you’ve got the palm patch over there, and the bromeliad hill over there- you get the idea.

My work here was mostly focused on another type of ant-plant. At Palo Verde I worked on the Acacia trees which housed Pseudormyrmex ants inside of hollow thorns. Here at Las Cruces you can find a whole lot of Cecropia trees, which house Azteca ants inside of hollow stems. The plant not only houses but also feeds the ants with food bodies it makes near the leaf stems. To pay the rent, the ants defend the plant from insects that want to eat it.

One of our faculty resource people, Cindy Sagers, introduced us to the Cecropia-Azteca work her group is doing. She brought us out to the forest with her eight foot sling shot, which they use to pull down large branches of the Cecropia trees. It’s harder than it sounds, getting a good slingshot-shot up and over a hundred foot limb that is surrounded by other vegetation. It is also a lot of fun to fire.

With my classmates Natalie, Haydée and Rick, we worked on Cecropia peltata, a species that lives along most roadsides in the tropics. By accident while trying to inspect a small sapling, I broke it off at the base, so Rick and I decided to dissect it and see if we could find the queens inside of the hollow stem. Amazingly, there were a lot of queens! In one of the hollow internodes, we found four queens of two different species. This seemed weird to us, since most large mature trees are thought to have only a single queen.

After our random discovery, and the fun of dissecting the saplings (it’s like opening Christmas presents since you never know what you’ll find inside), we changed our project to look more specifically at how ant queens were founding colonies.

The next day, with the queen founding in mind, we happened upon another incredible discovery- some queens actively founding a new colony! Because their colonies are inside of the Cecropia trees, they have to dig a hole using their teeth to get inside. This activity can be quite energy consuming, and so it would make sense to cooperate to dig a hole. That day was kind of crazy- I was doing a lot of running around, trying to capture all the activity of the ants. In total, we saw 13 fouding events, a third of them being cooperations between multiple queens. We watched three queens cooperate in digging a nest entrance for almost 6 hours- it sure took a lot longer than we’d expected! They kept digging and digging with their little ant teeth, and made very slow progress getting into the plant.

Aside from spending a lot of the day watching ants and dissecting their nests, I had a nice time at Las Cruces hiking around in the forest. There was a beautiful river trail, and lots of beautiful flowers everywhere.

I also enjoyed some delicious meals with friends in the comedor- we would sit down and eat family style, which is a nice change from cafeteria style serving. My favourite part of the day is sitting down to eat with my OTS family and enjoying some good laughs. They had some great bread for breakfast at Las Cruces, which was a nice change from the gallo pinto (rice and beans) of the past six or so weeks. I have had a bit of a gas baby lately (from too much gallo pinto I think), which has been the subject of many jokes. I hope the due date is soon! I am tired of having a bloated hurting belly!