Tuesday, June 30, 2009

The Sincerest Form of Flattery

There are small regions scattered across the east coast of the United States where, at the right time of year, in the right patch of habitat, you may have a chance to find perhaps the most beautiful amphibian in North America, the Pine Barrens tree frog, Hyla andersonii. Pine Barrens Tree Frogs are a small (less than 2 inches long), bright green frog with a lavender bordered light-brown patch running through its eye and alongside its chest. At the rear end of its body, the brown patch is blotted with bright yellow spots. It’s a striking amphibian that many photographers long to capture.


These tree frogs have an intriguing and unique distribution; only residing within the Pine Barrens of New Jersey (hence their name), the Carolinas, and the western Florida panhandle and adjacent areas of Alabama. Many herpetologists have spent considerable time pondering their patchy range. How groups of this little frog could be separated by thousands of miles begs an answer. Perhaps when the climate was more favorable to amphibians, Pine Barrens tree frog populations were connected by a vast expanse of wetlands. Before we drained, paved over, and developed so many bogs, swamps, and marshes across our country, perhaps there were more populations to fill in the gaps. Of considerable interest is how this frog has become slightly different within the remaining areas where they are found, without any gene exchange between populations, frogs in a particular area become suited to their local environment and over time, their behavior and morphology has begun to vary from other groups.

In any case, today this isn’t a frog you’re likely to find by accident. Unlike your typical bullfrog or green tree frog, which can be found in just about any wet area within their range, Pine Barrens tree frogs have very specific habitat requirements. Within Alabama and Florida you may be able to see one in the wet and acidic seepages and bogs that surround some small streams, in the thickest brush and woody shrubs you’ve ever encountered. It’s no surprise that this species evaded detection in Florida and Alabama until relatively recently (although they haven’t yet been documented in adjacent Georgia, the search continues).

The first individual Pine Barrens tree frog was documented in Florida in 1970 but we only began to better understand where they could be found in that state in the late 1970’s and early 1980s. Our knowledge of the frog’s status in Alabama developed slowly as well. Dr. Robert Mount, professor emeritus at Auburn University, recently came into the lab and related to me his surprise after being informed nearly 30 years ago that a Florida herpetologist had found the frog in Alabama. Mount, who wrote the book on Alabama amphibians and reptiles (literally), didn’t believe the news. For him to acknowledge that this creature was found in the state, he’d have to see it for himself, or, as it turned out, to hear it.

Male Pine Barrens Tree Frogs, like many frog species, call to attract females. As each species has a unique and specific sound, you can identify the frogs in an area just by listening. But it’s not quite that easy. Different species call at different times of year, typically at night and especially following rains. So, there is certain amount of skill and timing required to determine if a frog is present. But there are some other amphibian quirks that you can exploit.

Male frogs, although they desperately want all the nearby females to notice them, don’t want to be the only one singing in a pond. The frogs that tend to conduct solo performances are noticed not only by interested females, but are zeroed in on by hungry snakes and birds as well. As a result, most frogs prefer the relative anonymity of a full chorus of amorous amphibians before they’ll commence their crooning. But who’s going to be the first one to start singing? Dr. Mount, of course.

By imitating the Pine Barrens Tree frog call, a nasal and rapid-fire, “Kwek Kwek Kwek Kwek”, you may stimulate nearby frogs to follow suit. After Dr. Mount was convinced that this frog did indeed exist in Alabama, he initiated an intensive survey across the southern portion of the state to determine their status and distribution. After identifying and arriving at potential wetlands, Dr. Mount would get out of his car, stand near the water’s edge, hold his hands to his mouth and offer forth his best, “Kwek Kwek Kwek Kwek Kwek”. After only a brief moment, there’s a good chance that any present male Pine Barrens Tree Frogs would answer. And there’s an even better chance he got some very strange looks from passing motorists. As a result of his efforts and another follow up study, the species was documented at about 35 sites in three Alabama counties, just a small corner of the state.


When I learned I was to be conducting my dissertation field work in the Florida panhandle, the heart of the species distribution in the area, finding a Pine Barrens Tree Frog was at the top of my list of things to accomplish. When my Auburn officemate Sean Graham came down to visit, it was the excuse I’d been waiting for. Armed with a map of known locations, a group of us waited until dark and headed to some nearby creeks. As we drove along, we stopped at each creek crossing and piled out of the truck to try our luck. Tip-toeing silently to the edge of the creek bridge, Graham would let loose his best tree frog imitation and we’d all strain our ears to hear any response. After several performances with no appreciative amphibian response, Sean turned to us and exasperatedly exclaimed, “It’ll work better if there’s more people trying!”

Rolling my eyes, I raised my hands to my mouth, held one nostril close with my finger and added my amateurish, “Kwek Kwek Kwek Kwek” to our concert. In the distance, seemingly far from the wetland, we finally heard our answer. We all turned to each other to excitedly whisper to each other, “Did you hear that?” The consistent answer was, “Of course!” But the single frog we heard at the first site seemed too distant and not near any wetland we could distinguish.

Encouraged to know that our technique and our voices may prove irresistible to Pine Barrens Tree Frogs, we set out to another creek to find frogs that we might be able to see as well as hear. After arriving at the next creek and immediately after the night was filled with our enthusiastic amphibian impersonations, we heard several frogs echoing us from the wet areas alongside the stream, from within the deepest recess of seemingly impenetrable brush.

“I’m going in.” Graham shouted as he jumped into the thicket. He was instantly enveloped by the vegetation and made invisible, but we could hear him crashing through the branches and cursing. Thinking myself wily, I decided to walk along the stream edge until I was closer to where I had heard the calls before attempting to penetrate the thick shrubbery. I could hear Graham from the darkness as he periodically paused, give his best frog call, and wait for any nearby frogs to respond so he could get a better read on their location. After any frogs answered, the branch-breaking and cursing would resume as he neared his quarry.

Upon reaching what I felt was an encouraging spot; I took the plunge and began to part the branches in front of me. Despite the leaves and sticks thrashing my arms and face, I could still make out the sounds of both Sean’s imitation and the genuine article scattered throughout the wetland. At one point, after being enclosed by a wooden cell, I clicked off my headlight in exasperation and decided to just listen. When my light was off, I noticed that there were a couple frogs in the darkness surrounding me that would respond to Sean’s call from the other side of the stream.

Hoping to take advantage of this revelation while simultaneously eliminating the need for me to expose myself as a second-rate frog impressionist, I kept my headlamp off and waited. Before long, a nearby frog again answered Sean. The noise was not in the muddy puddles at my feet as I might have expected, it came from the tall shrubs around me. Hindered by a log at my thigh, I strained my neck and upper body towards the sound and turned on my headlamp. Instantly, I illuminated an emerald green frog almost immediately in front of my face and perched along an eye-level branch. Pausing to confirm I was gazing at what I had previously only seen immortalized within field guides and similar mediums, I admired the brown bib in striking contrast to the bright green back of the small frog. As I watched, he inflated his vocal sac and began singing.

“I’ve got one right here!”

It sounded as if a bulldozer was tearing through the swamp as Sean forced himself over from the other side of the stream. I waited until he had a chance to see the frog on the branch, minding its own business, before I attempted to catch it for posed photographs at a better angle. As slimy amphibians are wont to do, however, the frog squirted out of my grasp and into the inky depths of the woody thicket.

Before I was fully able to curse my bad luck, I noticed yet another frog less than a couple feet from the first. Determined not to make the same mistake again I focused on the frog’s location and slowly brought my hands around it. But as I closed in, the frog sensed danger and I saw him tense for a jump. Steeling myself for another disappointment, I watched the frog jump off its perch. As luck would have it, however, he landed straight onto my eyeball.

Surprised, I slowly raised my hand to my face and gently grasped the frog. I had found and captured the elusive and rare Pine Barrens Tree Frog.


All Pine Barrens Tree Frog photographs are courtesy of Aubrey Heupel, who along with Matt Greene are two skilled biologists and nature photographers (Fingerprince Prints Photography). I urge everyone to visit their website: www.fingerprinceprints.com to view their pictures. If you're looking for ideas for late birthday presents for me (and really, who isn't?) snake note cards would be exceedingly welcome.

9 comments:

Bailey Jones said...

When I was a kid, I was the neighborhood "expert" on reptiles and amphibians. One day my friend Johnny wanted help identifying a frog he had caught while vacationing in northwest Florida. We pored over the illustrations in my Peterson Field Guide, and soon he pointed to one and exclaimed "That's it! That's what I caught!!"

We flipped to the back of the book, and I pointed out that the frog he said he caught in Florida wasn't found south of North Carolina. But he was adamant, and for years he insisted that the book-- all of the books- were wrong.

Eventually, new editions of the books were released. When the Peterson was updated in 1975, he was quick to point out that "his" frog was now listed as living in Florida after all.

Yep, he had caught a Pine Barrens Tree Frog. I don't know when the first one was officially discovered in Florida/Alabama, but I always give my friend Johnny credit for catching the first one back in the late 60s/early 70s.

David Steen said...

Bailey,

Thanks for sharing that neat story. The PBTF was "officially" reported in Florida in a 1970 publication:

Christman, S. P. 1970. HYLA ANDERSONII in Florida. Quarterly Journal of the Florida Academy of Science. 33:80.

Sounds like Johnny was cutting edge.

Dave

Charles said...

It's always neat when you find what you're looking especially if it's a rare find like that little gem.

David Steen said...

You said it.

Chance favors the prepared mind.
Louis Pasteur

Bailey Jones said...

David,
I guess The Quarterly Journal of the Florida Academy of Sciences was a bit on the "heavy reading" side for a couple of grammar schoolers (Johnny would have been 5 in 1970, me a few years older) so we missed that one! :-)

Actually, Johnny might have caught his in 1970 or even sooner; we were both catching "frogs" (mostly Fowler's Toads) as soon as we could walk. But neither one of us will ever remember exactly what year it was; that's probably good, since it makes for a better story that way!

Mark Bailey said...

Another great story, Dave. I've fooled with these guys now and then and it's always amazed me how FAST a male can respond to my simulated call. I swear they're sometimes already calling back before I can finish my first "kwek." I once asked George Folkerts how he missed this species in Alabama before its 1979 discovery there by Paul Moler. In the 1970s George spent untold hours in pitcher plant bogs now known to have Hyla andersonii, and admitted that he'd almost certainly heard them, but must have written them off as odd-sounding H. cinerea. The lesson there is take nothing for granted, as even the best of us can miss important finds right under our noses. Example: three years after finding H. andersonii in Alabama, Moler was surveying for the species down in Eglin when he heard a frog call that neither he nor any herpetologist before him had ever heard. But that's another story...

David Steen said...

Wow Mark, I couldn't have imagined a better lead-in to my next column (to be finished shortly).

Thanks for sharing. I don't know if I would've thought much of their odd calls if I hadn't already been clued in.

levian said...

i am not a huge reptile fan, but this set of photographs really had me love the frog! nice shots!

David Steen said...

Levian,

Thanks for stopping by...I hope you like amphibians more than reptiles...

Dave