Of Birds and Insects (and a Coral Snake)

When I’m out here in the field I’m so focused on the birds (or the heat and humidity) that I don’t pay attention to all the other cool things, which often are insects. Like the two huge moths that mated for hours on somebody’s soccer shirt on the clothesline, or the big queen leaf-cutter ants that invaded our last camp and started digging new nests all up and down the trails near camp.

Today I saw a dragonfly with a jet-black body and thorax, scarlet abdomen and white eyes. I remembered seeing what looked like the same thing on last year’s inventory. I still don’t know what it is. Somebody probably knows, but guides to dragonflies for North America just recently became available. Such guides don’t exist for South America for most groups other than birds, mammals and amphibians, and reptiles in some areas.

Robin Foster, perhaps the best tropical field botanist, works with our team at the Field Museum in Chicago, and formerly took part in these inventories. He will join us in Iquitos at the end of our fieldwork to help the botanists work through the collections they’ve made and identify the photos they’ve taken. Robin has created a series of photo guides for plants that even a nonbotanist like myself can use to identify at least some of the huge diversity of plants in tropical forests.


Yesterday afternoon, I wandered into the heliport, where the herpetologists were photographing a snake. “Beautiful snake,” I said. “What is it?” The answer: Micrurus langsdorffi, a coral snake. It didn’t look at all like a coral snake to me. Underneath, all the black is missing, just red and yellow bands with narrow white lines separating them.
Back to birds, there are three different aggregations of interest in tropical rain forests — they are not randomly distributed. Fruiting or flowering trees can attract dozens of bird species. Unfortunately, not much is fruiting right now, and I haven’t seen a good fruiting tree full of tanagers, toucans, barbets and so on. But I still hold out hope. Yesterday, I found a flowering Symphonia right over Trail 3. It had dropped dozens of its round, red flowers on the trail, but there were still hundreds on the tree. It was not full of birds, but there was a nice selection including a moriche oriole, black-throated brilliant, white-necked jacobin, and the prize of the show, a male fiery topaz (aren’t hummingbird names great?).


My main interest is the mixed-species flocks. Thirty or 40 species can travel through the forest together. There are understory flocks led by Thamnomanes antshrikes — here cinereous and dusky-throated antshrikes. Canopy flocks are more variable, but the lack of tanagers has made them unimpressive here. I’ll spend an hour or more following a flock around through the forest. I used to routinely get lost (but never for more than an hour or two). Now my GPS device helps me get back to the trail.
The final aggregation is in many ways the most interesting. A set of birds follows army ants, eating the insects that are flushed by the ants. A number of species of antbirds and woodcreepers get nearly all their foods from the swarms. Today I found a nice little swarm of Labidus praedator (Eciton burchelli, also here, is the other important species for ant-following birds). The birds at the swarm today were a few bicolored antbirds, a couple of white-plumed antbirds, a reddish-winged bare-eye and a plain-brown woodcreeper. One thing that always puzzles me is that as you go from southern Mexico south through Amazonia to eastern Brazil and northeastern Argentina, the bird species at the swarms change, but in theory the ants are the same. One wonders if there is unrecognized diversity among the ants?