Steve Yanoviak, tropical biologist
Monday, 28 Aug 2000
MONTEVERDE, Costa Rica
I fell asleep on my couch last night after a dinner of black beans and rice (a.k.a. gallo pinto, literally “painted rooster”) and a couple glasses of cheap red wine. Gallo pinto is the meat-and-potatoes diet of most Central Americans, and I have grown to love the stuff. In fact, I crave it when I am in the States. Anyway, I awoke to a pin-prick sensation in my shoulder. I brushed it off thinking it was a mosquito, but then it returned in roughly the same place a couple of minutes later. I brushed it off again, and again it returned. I then realized that I was probably being bitten by a Chagas or “kissing” bug. This has happened to me before while sleeping on the very same couch. Sure enough, a quick search revealed the bug hiding just behind one of the cushions.
Excuse this biology lesson, but I think host-parasite relationships (and the evolutionary processes leading up to them) are fascinating. Kissing bugs are large (2-3 cm body length) brown or orange true bugs (order Hemiptera), and are common throughout Central America. They get their name from a habit of biting sleeping people near the mouth. Their other name comes from the fact that they transmit Chagas disease, which is caused by the protozoan Trypanosoma cruzi. The bug tends to defecate as it feeds, and the protozoan occurs in its feces. The bite itches a lot (often for several days), and the protozoa are inadvertently introduced into human blood when the sleeping person scratches feces into the bug bite. The trypanosomes persist in the human blood stream (to be picked up again by future kissing bugs) and cause slow degeneration of the nervous system. There is no known cure. Interestingly, it is believed that Darwin died from Chagas disease. Before you start wondering if I will die from this bite, I should tell you that not all kissing bugs carry the trypanosome, and Chagas is quite rare (perhaps completely absent) in the Monteverde area. Such is not the case in other areas — especially lowland forests — where as many as 80 percent of the bugs are carriers.
On to other topics … I said I would go up a tree today, but the weather was nasty all day and I did not get a chance to climb. The weather here is difficult to predict, but during this time of the year it seems to follow a cycle; several days of rain are usually followed by one or two days of at least partial sunshine. Yes, Monteverde is a pretty gloomy place to live at times.
Another lesson, but one I think is worth mentioning: Seasonality in the tropics is based primarily on rainfall instead of temperature and day length. (Days are always more or less 12 hours long near the equator, and my internal clock struggles through a major readjustment whenever I go back to Olympia, Wash.) In most tropical places, there are distinct wet and dry seasons. Local people refer to the wet season as invierno (winter), and dry season as verano (summer). Monteverde really has three seasons: 1) wet season, which generally occurs from June to November; 2) windy-misty season, from early December to late January; and 3) dry season, from February to May or June. Wet season is obviously a very rainy period. When there is a large low pressure system in the Atlantic — a hurricane, for example — it rains almost constantly in Monteverde for two or three weeks. Everything (clothes, sheets, boots) gets damp during these periods (called temporales) and quite literally develops a life of its own (fungi have a field day).
The windy-misty season is also wet, but more from cloud mist than rain. It gets its name from the trade winds, which drop to a lower altitude during these two months. Because Monteverde exists on top of a mountain with lots of open sea on either side, this is a windy place 90 percent of the year. Trees here generally appear “flagged” — all their branches and leaves grow facing downwind. During the windy-misty season, we get battered by especially strong gusts, and 100 kph (60 mph) sustained winds are the norm. Last year, the winds started tearing the roof off of my house. I spent every morning picking up the pieces and every afternoon putting them back in place with bricks to hold them down. A local carpenter made some repairs for me during the dry season, and I am hoping my humble little home fares better this year.
Dry season in Monteverde more than makes up for the other months. A typical Monteverde day in March is like the best spring day you can imagine in the U.S. The air is clean and fresh (except for dust from the dirt roads), the sun shines virtually every day, the clouds are high and puffy against a crystal blue sky, and the number of stars you can see at night boggles the mind. This is also a time of great cultural activity, with festivals, bull fights, and bicycle tours throughout the region.
Although I did not climb a tree today, I did prepare one to climb tomorrow or later in the week. When I tell people that I climb tropical trees and collect insects for a (meager) living, their first question is usually, “How do you get up there?” Tropical trees are generally very tall (30+ meters) and have few if any branches below their crowns. The only inexpensive ways to get up a tree are to climb up the trunk like Spiderman, or to string a climbing rope over one or more branches and haul yourself up. I use the latter system. Most tropical tree trunks are too smooth and too great in diameter to climb freehand. Plus, it is not a very safe way to go up (unless you are Spiderman).
Some simple materials and a lot of patience are all that you need to get a rope in a tree. My coworkers and I call this process “rigging.” I start with a slingshot, a fresh spool of fishing line, and a lead or steel weight. Here’s where the patience comes in. The object is to shoot the weight (with fishing line attached) over a solid branch with the slingshot. Much easier said than done. Usually there are multiple layers of leaves in the way, and a clean shot requires hitting a one-square-meter hole in the canopy, directly overhead, at a distance of 30 meters. I have been shooting lines like this for more than seven years, so I can normally hit what I want on the first or second shot. If I fail after three tries, I usually seek another tree or come back at a different time. I am not a superstitious person, but I do think there is some karma involved in this technique.
Today, the weight passed cleanly over a good branch on the first shot and came back to the ground without getting hung up. Fishing line is not strong enough to pull up a climbing rope, so I attached a 4-mm polypropylene cord to the free end of the fishing line and reeled it in — over the branch and back to the ground on the other side. I then tied an 11-mm static rock-climbing rope to the poly cord using a special “nail” knot, which has a low profile and makes it easier to pull a thick rope through branches and debris. I then tied one end of the climbing rope to the base of a nearby tree, and voilà, we’re all set to climb. When I am finished climbing this tree, I’ll leave the poly cord in place of the climbing rope so that we can climb the tree in the future without having to rig it again each time. At present, Nalini and I have over 40 trees rigged like this on the Reserve. I’ll talk about the equipment I use for climbing the rope later.
I hope to get up this particular tree tomorrow. From the ground, it looks like it supports a healthy epiphyte load, and that is what I’m after. I only climb in bad weather when I really need to (in order to stay on sche
dule for data collection). Nothing is pressing right now, so I’ll wait for good weather. Either way, I’ll be in the forest tomorrow and will undoubtedly have some interesting things to tell you about.