Night of the Bird Poop Frogs

Iquitos, a Peruvian river city accessible to the outside world only by water or air, has just one road leading out of town, a two-lane blacktop that runs for 60 km to the port of Nauta. The night before our tour group heads down the Amazon, we engage a van and driver and cruise the Nauta road (see my post ‘Road-Cruising in Amazonia‘ for more details). The experience gives our clients a taste of what’s to come, and a chance to get to know each other before the trip really kicks off.

This year our night of cruising proved to be a rainy one, not so good for finding snakes, but most excellent conditions for frogs. We stopped at multiple spots along the road to check out and photograph a variety of species. Coming back, one stop in particular led to an experience with a group of marbled treefrogs (Dendropsophus marmoratus), or as they are sometimes called, bird poop treefrogs.

Dendropsophus (formerly Hyla) marmoratus are pretty much the same size as the gray treefrogs found in the eastern United States. Their dorsal coloration is designed to blend in with their arboreal surroundings in a number of ways – they can look like:

• knobby bits of bark
• lichen on knobby bits of bark
• a steaming pile of fresh bird poo
• all of the above

The variations in pattern and color within this species is just amazing. The full webbing on hands and feet, along with flap-like fringes of skin along the edges of limbs, help to break up the typical frog profile (and result in some bizarre looking creatures).

At this particular stop, one side of the road was lined with head-high flowering bushes, just on the far side of a drainage ditch with a steep, muddy bank. Someone had spotted a Dendropsophus marmoratus on the outside of a bush, and I set up my camera and flash and went to have a look. This entailed jumping the ditch and then easing up the nearly vertical bank, and then digging in with my boots to maintain some kind of semi-steady toehold. The frog was still there, doing its best bird poop imitation (see above photo). I could hear males singing from somewhere within the bush, and to my right I spotted a pair of marmoratus in amplexus, tucked away under some leaves and looking like anything but two froggies en flagrante delicto.

Then there was movement to my left, as a male climbed up to a better perch from which to sing its song. Part of my fun with frogs is attempting to photograph calling males with their throat sacs full of air. Success varies from species to species, and some are easier than others; some frogs have a reliable cycle of fill-croak-fill, which can be anticipated, while others are unpredictable. Some frogs fill their sacs very quickly, and the trick is to depress the shutter just before you think you should. The bird poopers fell into this last category. It took me more than a dozen tries before I caught one at ‘full sac’; fortunately, most male frogs are focused on calling in a female, and are not paying much attention to a macro lens six inches away from their face. I could relate, as I was deep in the frog zone, paying no attention to what others on the herping bus were up to; they could have been wrestling anacondas for all I knew.

Mission accomplished, I relaxed (as much as one could with one’s toes dug into a muddy bank) and enjoyed the proceedings. There were at least four other males calling from deep within the bush, and I recorded their singing (play the sound file in this HerpMapper record). Several females were present as well, presumably enjoying the concert as much as I was, and weighing their options for a mate. It looked like tonight was The Night for carrying forward the next generation of bird-poop frogs.

I may have mentioned elsewhere that photographing frogs while precariously perched and / or soaking wet is my happy place, and this night had the added bonus of some interesting natural history observations and voice captures. And all it cost me was a pair of wet, muddy boots and later, a bad case of chigger bites on both ankles.

Enjoy a small gallery of marmoratus from northeastern Peru.

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