The Madre Selva field station is on the banks of the Rio Orosa, and if you go out on that river at night, you can find Spectacled Caiman (Caiman crocodilus) in the quieter backwaters, their eyes glowing red when hit with a flashlight. Go up the shallow side creeks and tributaries and you have a shot at the smaller-sized Smooth-fronted Caiman (Paleosuchus trigonatus), lying under cut banks and in the deeper pools. But if you like your crocodilians enormous and elusive, you must push into the flooded varzea forest, away from the big rivers and the people who would hunt the Black Caiman.
In 2011, the water was low enough that a group of us hazarded a slippery trail to Lunes Cocha, a small open lake a few miles from the Rio Orosa, and home to Melanosuchus niger. The low water that afforded us foot passage also meant that there was little water in the lake, and it was completely overgrown with aquatic vegetation. We came back mostly empty-handed; I brought back a left hand full of palm spines, thanks to an unfortunate stumble.
In 2015, the water was high enough for us to paddle to Lunes Cocha, and since our skiff could not navigate the twisty route through the flooded forest, a couple local boatmen were hired to help us out. After supper, as the sun fell towards the horizon, we left the field station in two dugouts and two single-seat kayaks. Each dugout was long enough to hold four people, the gunwales a scant inch or two above the water, and the hired boatmen steered from the front. I sat directly behind Tomás, a man of remarkably few words. After a lifetime on the waters here, he knew what he was about, and after floating down the main channel of the Orosa for a while, he bore left and the dugout plunged into the forest. Tomás threaded gaps between trees and turned us left and right and left again, and as the sun touched the horizon we pushed through a last thicket into the waters of the lake.
Waiting for dark, we shot a spectacular sunset and listened to the gobble-shriek of a pair of Horned Screamers (Anhima cornuta). When he deemed it sufficiently dark enough, Tomás strapped on a cheap headlamp that seemed no brighter than a candle. Steering the dugout along the lake’s edge, he began calling out to unseen crocodilians with a grunting ‘unh-unh-unh’. Almost immediately, several juvenile caiman responded from somewhere in the thick vegetation with higher-pitched, squealing grunts. Floating along, Tomás grunted again, and this time the response was a throaty, roaring rumble that I felt as much as I heard; Mama Black Caiman, unseen but close by her squeaking babies, enormous in my mind’s eye and probably in real life. Tomás turned his face and shot me a snaggle-toothed grin.
Black night now, and we steered towards caiman eyes glowing red when our headlamp beams hit them. The first proved to be a yard-long Spectacled Caiman, too big to mess with and not our intended target, and the next two sets of eyes belonged to smaller Spectacles. Tomás snatched one of them out of the water, just for fun or maybe to demonstrate to the gringos how it was done. For the fourth set of eyes, he merely pointed, and I took that to mean it was my turn. The little Black Caiman floated in the glare of my headlamp and I grabbed it up, hand behind its head and one thumb circling a front limb.
Around eighteen inches long, it carried the dark body color of adults, crossed with thin transverse yellow bands. Not quite a neonate, the eyes were still disproportionally large, but it wouldn’t be long before the little caiman grew into them. I took a few one-handed shots, and then popped the caiman in a sack – it would be coming back with us for photographs, and then brought back to Lunes Cocha the following day. I could hear voices floating across the lake from the other dugout as they landed their own small Melanosuchus.
We saw more small-to-medium Spectacles and Blacks as we circled Lunes Cocha, and then Tomás plunged us back into the varzea, and we made our weaving way home. Reaching the main river, trailing my hand in the black water, I caught a glimpse of a ghostly Pipa toad before it swam under the dugout, and I added it to the things I would remember about this night, along with the Horned Screamers, Mama Caiman’s rumble-roar, and a handful of Melanosuchus niger dripping water on my leg.