Panama - Sloths and Other Cool Creatures

One of our mist netting sites was on Barro Colorado Island (BCI), a world famous tropical research site in the middle of the Panama Canal. The nearly 4,000-acre island is managed by the Smithsonian Tropical Research Institute (STRI) and hosts hundreds of researchers each year. The island is reached by boat. In 1983, a train ran from Panama City to Gamboa and then to Frijoles, an abandoned village. The train station at Frijoles was the launch site to BCI. Years later the train stopped running to Gamboa and Frijoles, so the boat launch to BCI is now from Gamboa.

The Panama City-Gamboa-Frijoles train

The Frijoles train station, 1983

What is now Barro Colorado Island was once part of a high ridgeline and a large connected intact tropical forest. The creation of the Panama Canal flooded a large area, creating Gatun Lake, a large water body that now surrounds BCI. As such, it became an important area to study the birds, plants, mammals, insects, and other diverse taxa in a relatively undisturbed area. And the diversity is extraordinary: 381 species of birds; 135 species of mammals including five monkeys and 70 bat species; 32 types of frogs and toads and 58 reptiles; 100 species of ants; 150+ species of vines; and so much more.

One of our favorite sightings on BCI was Alice the tapir. She visited the laboratory on BCI in search of kitchen scraps. This happened mostly during years of food shortages. Tapirs look like a cross between a pig and a rhinoceros with a long, flexible nose and a short, stubby tail.

Alice the tapir on Barro Colorado Island

Another wonderfully interesting mammal is the three-toed sloth. We saw these on BCI, on the mainland, and on a trip to the highlands of western Panama. On this latter trip a sloth climbed down from a tree and walked across the lawn of the cabin where we were staying.

A three-toed sloth in Cerro Punta, Chiriqui Highlands, Panama, 1983

Sloths move very, very slowly on the ground. They spend most of their time in trees, where they also move slowly, blending in with the leafy canopy, the source of their food. Blue-green algae grows in their fur, adding a greenish tinge to their coat, which further camouflages them from their main predators--jaguars and harpy eagles. Several species of insects live in sloth fur, feeding on the algae. Sloths climb down from their tree once a week to relieve themselves. On BCI alone, their are several thousand sloths. Nice to know that these extraordinary creatures are faring well.

Our apartment in Gamboa was clean and airy. But the first morning, when we flipped on the kitchen light and watched cockroaches scurry into dark corners, I realized I was in a different ecosystem than my native New England. Our apartment cockroach was just one of more than 100 species of cockroaches found in central Panama. Not only are there many more species of each taxa in Panama, most animals and plants are bigger than comparable species here in our northern climes. Take the foot-long stick insect that was stuck in one of our mist nets. At first glance it looked just like a stick, until we saw it move ever so slowly.

 A big stick insect (commonly called a walking stick) in Panama, 1983

Ants were never so interesting until I spent time in the tropics. I mentioned army ants yesterday. Another fascinating group are the leafcutter ants. These colonies can contain millions of ants, divided into castes based on the work they perform. Leading to the colony are small, hard-packed paths traveled by the larger worker ants that carry fragments of plants back to the colony.

A leafcutter ant with flower fragment (Photo by Larry Kolczak)

The large ants turn their plant cargo over to mid-sized ants that carry the material into the ant mound to the fungal garden. Leaf-cutter ants feed the plant fragments to the fungus. Smaller ants inside the colony tend to the garden by removing mold and weeding it of other pests. Any debris--leftover plant fragments and dead ants--are carried outside and taken to a dump site at the edge of the mound. Young ants feed on the fungus. We watched in awe as a steady stream of ants carried leaf and flower parts into the colony and an equally steady stream of ants carried debris out to their "landfill." Some ants--the soldiers--defend the ant colony and others ride on the backs of the leaf carriers to fend off parasitic flies. It was a marvel.

The trees, vines, flowers, and fruits were equally diverse and uniquely adapted to their tropical habitats. There was not the time to learn the thousands of species, but time enough just to enjoy their shapes and colors and beauty.

A rich diversity of plants in Panama

While mist-netting birds we listened to the booming calls of howler monkeys and watched troops of white-faced and spider monkeys. One troop of white-faced monkeys was overhead on one of netting plots. They looked down at us, breaking branches, bringing them up over their head and bringing them down hard on another branch. It seemed like aggressive behavior aimed at us, but we were after-all another primate in their territory. We saw agoutis (a rodent), coatimundis (raccoon-like), lizards, beautiful butterflies, crocodiles (in Gatun Lake).

Tomorrow -- the Panama Canal before, during, and after 1983.