Night Hike in the Rainforest

Notice: No flash photos at night...

     This hammock feels good; this beer, even better. The air and the beer are warm, but that's something I've become quite accustomed to. Upon thinking about it, I might actually prefer the beer to be warm, at least the flavor of a familiar Imperial. Back in the United States with a Sierra Nevada, that's a different story. Anyways, aside from that brief mental tangent, it's not beer or hammocks that are on my mind. At this moment it is the multitude of frog calls that are serenading me from the nearby forest and stream- one of which, I'm pretty sure is a new species of transparent glass frog, is calling from somewhere quite close. Dik Dik Dik... he repeats. There is a tree, no higher than five or six meters tall, growing over the stream and crowning right next to a bridge...he must be there. That's my queue. The last ounce of warm beer disappears down my throat, my body rolls to the right, and my bare feet touch the gravel covered floor. Within ten minutes I have eaten an avocado, three tortillas with black bean spread, changed into my field clothes, and am once again in my knee-high green rubber boots. The sun has not yet completely set, but it is close. I am not used to so many different species of frogs calling so early. There are a few I can recognize, and a few that are a generic mystery "Quawk!" which are begging to be found.

     I head left from the cabina with the idea of hiking a short trail that borders a "lagoon", and from there working my way into a shallow, less than 10 meter wide river.The idea is that the lagoon trail should afford me the chance to find the calling tree frogs, and the river- the glass frogs.

Northern Cat-eyed Snake
Leptodeira septentrionalis

     On my way to the nearby trailhead I cross over a bridge. Just on the other side, to my right, there is a cream colored scaly belly making its way up through some vegetation. I grab the snake and immediately recognize it as a cat-eyed snake. A moment later, after a look at the snake's neck, I identify the species as a Northern Cat-eyed snake (Leptodeira septentrionalis). The snake is placed in a plastic bag which is tied closed, and then hung from my belt, as so many of you have seen me do before. Soon afterwards the trailhead appears on the right. I hop down on the trail and make my way around the perimeter of the lagoon. Before reaching the end of this trail, all of the usual suspects make an appearance. I hate to use the word usual (almost as much as I hate the word rare) because regardless of how commonly seen these species are, they are all nothing short of SPECTACULAR! Hourglass tree frogs (Dendropsophus ebraccata), Masked tree frogs (Smilisca phaeota), huge adult male basilisks (Basiliscus basilicus) sleeping overhead on cartoonishly thin branches, a juvenile Northern Cat-eyed snake (Leptodeira septentrionalis) which still has its bright white nuchal collar, a Spectacled caiman (Caiman crocodilus) its eyes reflecting back a glowing orange, plus a few more old friends.

A young Northern Cat-eyed Snake
(Leptodeira septentrionalis) showing
off a bright white nuchal collar

Upon first glance this
Dipsas was mistaken
for a Cloudy Snail-eater
Sibon nebulatus

     As this trail comes to an end, up and to my right is a black and silver snake called Sibon nebula-NO! I grab the snake, it's not even a Sibon! It belongs to a genus of snake that I have never had the privilege of seeing before. A Dipsas; what fortune! The exact species is Dipsas tenuissima. Like the members of the closely related Sibon snakes, Dipsas are specialized eaters of snails and slugs. They have modified teeth on their jaw that are used to extract the snails from their shells. Again I use the word- SPECTACULAR! The genera of Dipsas and Sibon are collectively referred to as the goo snakes, due to the contents of their stomachs (gooey snails, slugs, and frog eggs) when you try to examine what they've eaten. Finding a new species of reptile in Costa Rica is becoming harder and harder, much more so a new species of snake. He is bagged and hung from my belt as well, to be released the following day, but not before a photo shoot.

Upon closer inspection, the head of this Dipsas tenuissima
looks quite different than that of Sibon nebulatus

     Well, enough with the casual searching and the lucky finds. It's time to get down to business- the business of glass frogs. At once I jump down into the river, for the moment with the water level still below the tops of my boots. I turn off my lights to minimize the distractions, and shut my eyes- as if this matters in the pitch blackness. Yes, they are here, "all around". By all "around" I am referring to the three-dimensional world of a climbing rainforest organism. Sure he is calling from less than two meters to my left, but it also happens to be somewhere between one and thirty meters up in a tree...

    An interesting fact related to the frustration of hunting for glass frogs: Human ears are placed more or less symmetrically on our heads, whereas an owl's ear openings are offset- one being higher than the other. This affords them, while limiting us, the ability to determine the vertical location of a sound. As humans we are really only efficient at determining a sound's origin on a horizontal plane.

If you want a true account of what it's like to search for glass frogs in the rainforest READ THIS!
http://amphibios.org/blog/glass-frogs/
While you're at it, read every entry on this page. It was created by my very good friend Tim Paine (T-Paine!). He is an accomplished photographer, a talented biologist, teacher/mentor to many, friend and inspiration. And that's not even his day job...

Searching around the river yielded eggs
 of the glass frog Teratohyla pulverata

     By this time, a light rain had started, though it's more snow flurry-like than rain. The water has since entered my boots- owing to an encounter with a medium sized Spectacled Caiman, Caiman crocodilus (the caimans in these parts are comparable to a slightly smaller alligator). In my spotlight, reflecting back at me was a pair of bright, and what appeared to be frog eyes, coming from the river bank. After a few quick steps, I was upon the 3.5 foot "frog", with a snout full of pointy teeth. As is typical, the caiman made a lunge to escape into deeper water in the opposite direction. As is also typical, I followed. Now I'm up to my waist in the river, holding this crocodilian, and there's no one around to share the moment with.

     A few minutes later I found myself balancing on the top of  a fallen tree that was across the river, holding a stick, stretching up as far as I could, trying to get a better look at some overhead leaves from which a glass frog was calling. Then it hit me. I sat down on the log, turned off my light again, and I thought:


"...you are walking around in a deep rainforest, somewhere far from home, you are soaked, wading through a stream in the rain, it is dark all around you with mysterious sounds making your mind wonder “what is out there”, and you realize you are doing all of this to look for little green frogs with clear bellies. What the hell am I doing? You think – this is weird. “I’m weird”. Life is good!" - Tim Paine

Teratohyla pulverata gets it's name from the fine
white flecking on the frog's back.
"Pulver" comes from the Latin word for dust.
Many other languages also share some form of
the word "pulver" meaning powder or dust.

PURA VIDA

-Don