I looked at my watch again. Susan Laurance, one of the researchers and my invaluable guide to the secrets of this rainforest, had told me to listen for howler monkeys at dawn. With my city sense of schedule, I fiddled with the buttons of my watch some more and got the dial to blink up at me again. 12:40 am... maybe this wasn’t them? But I was increasingly sure those must be howlers, the alpha male’s neck pouch giving a biological wah-wah tremulo to his voice as he called to his band high in the trees, somewhere off in the dark.

I decided I’d better record this strange recital. It might not come back again during my 36 hours in the field. Gingerly I checked my sneakers below the hammock for—what was it they’d warned me about? Scorpions? Snakes? For things I now realized, in the middle of the dark night with everyone sound asleep and this odd roar in the air above, I really should have asked about more carefully the evening before.

I unpacked the video camera from its sets of plastic Ziplock bags (guess I’d been more careful to follow suggestions for the camera than to protect my feet!) and made it back inside the mosquito net that enveloped my hammock. Though Susan had told me there were very few mosquitoes here, and our mateiro/woodsmen guides chose not to rig up theirs, I somehow felt safer against the unknown back behind the netting. After a full 20 minutes of howling that would have done the "Scream 3" soundtrack proud, I pushed the ON button, pointed the camera and its microphone up into the dark... and the monkeys promptly stopped. How did they know, up in their tree-tops, that the tourist down on the ground had just gotten ready to record their recital?