6 Go to the ant, you sluggard;
consider its ways and be wise!
7 It has no commander,
no overseer or ruler,
8 yet it stores its provisions in summer
and gathers its food at harvest.
Proverbs 6:6-8, NIV
Ants and their sophisticated habits have intrigued people for ages. The above noted passage in the Bible proves that: the book of Proverbs was written in the 2nd century before Christ. Here in the tropics I’m also confronted with the never-ending motivation of ants. While I’m continuing my path up a hill, sighing and groaning, I see leafcutter ants carrying their load with indefatigable strength. A continuous line of moving green leaves shows me the way to the top, while the setting sun frames the rocking leaves and their carriers.
These ants definitely fit the category described in Proverbs. Ants, along with bees and wasps, belong to the order Hymenoptera. Many of these insects are eusocial or live highly organized in castes. Every member of the colony is related to the other members, making them work in the interest of the bigger picture – the colony. This social strategy is extremely successful: Hymenoptera make up two percent of the world’s millions of insect species, but they represent eighty percent of its insect biomass.
In the neotropics, Atta colonies are a phenomenon: a colony contains up to several million ants, all of them female (except for the brief period in which they reproduce), all of them offspring of one fat, egg-laying queen. The rank and file are organized into castes that perform the chores that keep a colony alive and growing. Large workers clip fragments from leaves, then pass them off to medium-sized ants inside the nest. This caste chews the leaves into a pulp, but before they lay it on the fungus bed, they squirt the fungus with a drop of faecal liquid. It contains all twenty-one amino acids, essential for the fungus’s survival. The fungus, one of the Basidiomycetes group, digests the leaves’ cellulose, a feat the ants cannot perform themselves. And then the colony eats the fungus. The smallest caste of workers, called minims, nurse eggs or tend the fungus garden, cleaning and weeding it of any alien growth and keeping the culture pure. These remarkable leaf cutters not only invented agriculture far before people did, but they also figured out a way to exploit the abundance of energy in leaves by getting fungi to break down the terpenoids, alkaloids, and other sickening chemicals that tropical leaves use for protection against herbivores.*
Every day you’ll encounter these animals here. And every day these ants remind you to work hard yourself. I’m not the only one here in Gamboa who sometimes feels lazy compared to these ants, earlier one of my colleagues sighed that too. The well-known Facebook façade causes people to ask me: “Do you even work there? Or do you only do fun stuff?” Time to investigate my own work ethic!
While the bats flitter around my head, I look at the screen of my video camera. The pixels show a frog: he moves a little, searches for the right angle and decides he feels comfortable. He hears another male calling, but doesn’t respond quite yet. Another call, and another. He can’t let this happen, if he won’t start calling the female will chose his rival over him. He sounds a hoarse call, clears his throat and fills his abdomen with air. ‘Tuuuuun—tuuuuun—tuuun’, it sounds. The frogs respond to each other and are involved in an acoustic battle. “Tuuuuuun-gara”, the other frog calls. Things are getting serious: the ladies love a complicated call, and that gara addition in the call is irresistible.
That is a typical description of my current experiment. Whenever the weather allows it, I go out to observe frogs. This is the first part of my experiment: observe the natural behaviour of frogs. When I have collected this data, the second part of my experiment will focus on the interaction between bats, frogs and blood-sucking flies.
Trial and error
A couple of weeks ago I started my experiments in good spirits. The first month in Panama I spent discussing, adapting and optimizing my experimental design with my supervisors. I gave a presentation to receive feedback and afterwards incorporated the feedback. At that point one thinks: nothing will get me down. Unfortunately I’m doing field work. The first two weeks I had literally zero (o) data points. That wasn’t because of too little work days (as was rumoured by some), but because of the fact the frogs weren’t behaving as we thought they would. Back to the drawing board! I designed new, simpler experiments with my supervisors. The past weeks I’ve been working with this design and I’ve actually been getting some data: we’re making progress!
With these experiments I’m trying to assess how the frogs behave in their natural environment. More specifically, I’m curious to see whether the frogs behave differently in vegetation or in open water. Currently I’m filming the frogs when they’re calling: this allows me to analyse their calls to see whether they adapt their calling behaviour to their environment. Aside from that, these video recordings also provide me with the opportunity to score the number of blood-sucking flies that harass the frogs. The hypothesis is that more of these annoying frogs can be found in the vegetation than in open water. Unfortunately I know exactly how the frog feels: while he is being harassed by the blood-sucking flies, the blood-sucking mosquito’s easily know how to find me (I counted 122 bug bites the other day). Resignedly we beat the flies off in the same rhythm.
Threat in the leaves
At least field work in the tropics is never boring. The other day I was calmly observing my frogs, when something moved to the left of me. The tropical rainforest is never quiet and always in motion, so I didn’t expect a lot. While my experiment kept running, I pinched my eyes to see a shape in the red light of my headlamp. I saw something crawling, gliding almost. A fluid movement, writhing from left to right, showed the presence of a snake. A snake is one thing, the species of snake another. In the dim light the snake looked like a coral snake: together with the fer-de-lance I saw earlier the most venomous snakes here in Panama. Even though there are more than ten species of venomous coral snakes and just as many non-venomous fake coral snakes, I decided it’s better to be safe than sorry. While I kept half an eye out on the pile of leaves on less than a meter distance, I packed my stuff and went home. My colleague Michael afterwards confirmed that it was a good choice: he’s 90% sure it was a many-banded coral snake (Micrurus multifasciatus). The threat had made me return home earlier to a farewell party that was going on. Luckily, the encounter with the snake brought me something good: a nice wine in good company!
* The Tapirs Morning Bath, Elizabeth Royte (2001), p. 194-195