Spent a couple of weeks in Panama during the summer of 2024. I went on the Canopy Family Herpetology at the Isthmus tour, which was great.
Of the 32 species of anurans we encountered, I was able to record 17+ species. Of those, at least 12+ species were new to my recording lifelist including:
The Panamanian Humming Frog (Elachistocleis panamensis) is an odd, pointy-nosed microhylid that occurs from central Panama into the lowlands of Colombia and Venezuela. It is related to our North American Narrow-mouthed Toads (Gastrophryne sp.).
They are generally dark with a brownish-yellow back and an irregular, dark mid-dorsal stripe. The mid-dorsal stripe is split by a thin yellow line from the tip of the pointy nose to the end of the body.
The common name "humming frog" is derived from the calls of other members of this genus in South America whose calls are reminiscent of a humming sound. But this northernmost representative of the genus has a completely different type of call. The call of the Panamanian Humming Frog is more of a high-pitched whistled trilling sound. It reminds me somewhat of the high-pitched trill of the Australian Rain Frog (Austrochaperina pluvialis)
I heard these frogs calling from a flooded grassy ditch after some heavy rains in the Tocumen marshes of Central Panama. The call of this species is fairly high pitched for a frog, with a carrier frequency ~5kHz. Because of the high pitch of this trill, I assumed it was an insect until I got home and did some research.
The Panamanian Granular Toad (Rhinella centralis) is a small flat-headed toad found in Panama. It used to be considered the same species with the widespread South American Granular Toad (R. granulosus) but it was elevated to its own species in 2009.
When I read about these toads and saw pictures of them, for some reason I thought they would be medium to large sized toads since many Rhinella species are very large. I was rather surprised when I found these toads along a dirt road through the Tocumen Marshes in Central Panama just how small they were.
As you would expect for a toad of this size, it's call is a high pitched trill lasting around 3-4 seconds and with a carrier frequency (dominant pitch) of around 2.5kHz. In general pitch, it reminded me of the call of the North American Red-spotted Toad (Anaxyrus punctatus), although that species has a longer trill.
Here's a couple of Panamanian Granular Toads calling next to each other in the Tocumen Marshes -
As so often happens when you are trying to record one species of frog, another species right next to it pipes in and makes it hard to get the recording of your target species. That's what happened in this recording. I was trying to record a Colombian Four-eyed Frog (Pleurodema brachyops - the hollow "ponk, ponk") when a couple of Panamanian Granular Toads started calling right next to them, and then a Tungara Frog (Engystomops pustulosus) added its "toy ray gun" "PEUW" song to ruin my recording.
Panama Snouted Treefrog photo by Angel Sosa-Bartuano. Used under CC-by-NC license granted on this iNaturalist record.
The Panama Snouted Tree Frog (Scinax altae) is a small, striped cone-nosed treefrog of the grasslands and marshes of the Pacific versant of Panama and into SW Costa Rica. It appears to be a southern, isolated sister population of the widespread Stauffer's Treefrog (S. staufferi) which occurs in Northwestern Costa Rica and north into Mexico.
I recorded these frogs in Central Panama just east of the Tocumen International Airport. In fact, you can hear a plane taking off in the recording!
It had rained heavily earlier that day and the frogs were calling from some flooded marshy pastureland after dark. When I first heard their buzzy call, it reminded me of a Scinax species, but I couldn't match it to any particular species I knew. It sounded like S. staufferi, but I knew that species wasn't found in Panama. I decided they must be Yellow Treefrog species (genus Dendropsophus).
It was only after I got this record uploaded to iNaturalist that another user pointed out the correct species identification. A little research online and I ended up with another new frog for the lifelist! And a new Scinax to boot - one of my favorite Neotropical hylids.
Barrio-Amoros, C., Forero-Cano, A.M., Stuster, R., Batista, A., Canzoneri, M., and Arias, E. 2023. The presence of Scinax altae (Dunn, 1933) in Costa Rica, with redescription of its advertisement call. Anartia 37:34-46. https://zenodo.org/records/10516165
Slim-fingered Rain Frog (Craugastor crassidigitus) Sarapiqui, Costa Rica
The Slim-fingered Rain Frog (Craugastor crassidigitus) is a small frog of the Central American rainforests through Costa Rica south into Central Panama. Like most of the other Robber and Rain frogs from the genera Craugastor, Diasporus and Pristimantis, this is a highly variable species and can be difficult to identify in the field. They are tan or orange with a tuberculate skin and long toes with flat toe pads. Of course, that describes many similar species of these genera in Central America.
There are two types of calls associated with C. crassidigitus. One call is described as a "bird-like chirp" while another has been described as a "chuck chirp". The chuck chirp is believed to be used for territorial communication. It was described in Roberto Ibanez's CD of Panamanian Frog calls as the "sporadic call".
I hear this call as sort of a "hoarse chirp".
I recorded what I presume to be the chirp calls as we walked along a dirt road in the Anton Valley of Panama. The frogs were calling from a heavily vegetated hillside next to the road. Even though there were lots of these frogs calling, as is typical, we had a hard time finding the singers.
We eventually did find one of these frogs and see it making this call. Unfortunately, my photo of that individual "left something to be desired" 🤣.
Banded Robber Frog photo by Khristian Venegas Valencia Photo used under CC-by-NC license granted in this iNaturalist record
The Banded Robber Frog (Pristimantis taeniatus) is a small, forest dwelling robber frog of Central America. It is also known as the Banded Rain Frog, but I prefer the name Robber Frog for this genus to avoid confusion with the many other "rain" frogs around the world.
This species is found from the southern tip of Costa Rica through the lowlands of Panama and into the lowlands of northern Colombia. Although it has "banded" in the name this species is generally rather nondescript tan or orange frog with warty skin, flattened toe pads and a dark marking posterior to the eye. Unfortunately, that is a description that fits hundreds of species of frogs in the genera Diasporus, Eleutherodactylus, Pristimantis and Craugastor. These Central American Robber frogs can be very difficult to tell apart visually. That is why I have had to use a creative commons licensed photo from iNaturalist for this post - I don't know if any of the "robber frogs" I saw in Panama are this species or not because I didn't see any calling.
Fortunately, this species a fairly distinct call quite different from the similar species in this area. The call is a slow dry trill, almost a slow creaking call. It stands out fairly easily in the lowland rainforests of Central Panama where I recorded these individuals.
It is difficult to record though since it calls very sporadically and unpredictably so I have had to remove some of the long periods of quiet between the calls.
The Chiriqui Glass Frog (Teratohyla pulverata) is a delicate Centrolenid frog found from the lowlands of northern Honduras down through Costa Rica, Panama and into western Colombia. It is pale green with faint white or yellow flecks on its dorsum and, like most glass frogs a transparent skin on the ventral side.
The Chiriqui Glass Frog has the other character of being the ONLY species of Centrolenid frog I've ever seen in the field at the time of this writing! I have been in glassfrog range many times and have actually recorded 4 species in two genera, but I have never been able to see one before this one pictured above.
I spotted this little guy/girl sitting on the edge of a broad leaf at the edge of a heavily vegetated creek in the Piedras Blancas National Park of southern Costa Rica. I was ecstatic to finally have see a Centrolenid frog, but I wasn't sure I was going to be get closer to it since I was on a bridge over the creek.
So I made my way over to that bank and slowly crept down through the dense vegetation (trying not to step on any Terciopelos on the way 😟) and also not shaking the leaves of the giant plant he was on. I finally got close enough to get a couple of pics, including an attempt at the compulsory "light through the translucent glass frog" shot.
But because of where it was sitting, I couldn't actually catch the frog for better posed photos. 😢
So I was very excited to finally see a Centrolenid Frog......but it wasn't calling. I went through my recordings from the forest in that area and couldn't find a single call that matched the description of this species call? Bummer.
But after I was home and going through my Costa Rican recordings, I came across a recording of a high pitched Glass Frog type call from the Sarapiqui area of Costa Rica from the previous week. I am not sure why I didn't upload this one to my blog with the rest of my Costa Rica entries, but better late than never?
But after some reading in what resources are available, I have determined that it must be this species?
Like many glass frogs, the call of this species is a high-pitched, thin peeping, repeated in a series of three notes. According the literature, the carrier (dominant) frequency of the calls is supposed to be in the 5500-6200 Hz range and mine is in the 5100 Hz range, but I can't find any other frog species with a similar call. So for now, this was a Teratohyla pulverata call until I hear otherwise? There are a number of photo records for this species at this location in iNaturalist corroborating their presence there, so I am pretty confident I have the right singer.
FINALLY......I recorded a Pickerel Frog calling!!!
EDIT April 2024 - Finally I saw a wild Pickerel Frog! I added this photo of the pickerel frog I photographed in Missouri in April 2024 because.....I saw a Pickerel Frog! (The original photo above was a captive from NC that I photographed in 1995).
The Pickerel Frog (Lithobates palustris) is not a rare frog. It is quite common and widespread across the eastern United States. Unfortunately, it is not common nor widespread in Texas and in spite of decades of looking for them, I have never seen or heard one.
So, as is a long-standing tradition for me, I made the long drive into the forests of East Texas during the spring of 2024 to see if I could find one of these little "snorers". Unfortunately, although we had had warmer than average weather in the preceding week and some rain had fallen, the night I arrived at the Caddo Lake National Wildlife Refuge it was cooler than usual. We drove around listening and recording Spring Peepers and Cajun Chorus Frogs hoping to hear something else. But by 9pm, the temperature had dropped into the low 50s and that usually puts a damper on frogs calling in Texas on dry nights.
Right before we were headed back to the hotel, we stopped at one last flooded roadside forested area. This spot was right next to the road and train tracks so it was full of trash and plastic bottles - hardly a pristine vernal pool.
I recorded some Spring Peepers and some Southern Leopard Frogs when suddenly, I heard a long snore just a few feet away into the forest.
Pickerel Frog!!!!! After years of standing in the cold on spring nights, I finally found one!
The call of the Pickerel Frog is maybe best described as a long snore, although there is a percussive component to the spectrogram that you don't see in the "buzzy snores" of the Spadefoots.
Here's one of this frog's "snores" -
Unfortunately, we were tired and wet, and there was a barbed wire fence keeping us from getting over to see the frog, so I substituted a captive photo from decades ago. I guess because we were so tired (it was a 6 hour drive to get there, and we had been listening to frogs in the cold for several hours already), I decided that we would come back tomorrow night when it was forecast to be warmer and get a nice stereo recording.
Needless to say, the next night it was just as cold and there were no Pickerel Frogs calling. I'm glad I at least got something the night before.
That is my 38th of the 42 (maybe 44 now) species occurring in Texas. Maybe I can get lucky and knock off another two this year? I still need Houston Toad (Anaxyrus houstonensis), American Toad (Anaxyurus americanus), Pig Frog (Lithobates grylio), and White-lipped Frog (Leptodactylus fragilis) of the native species and Greenhouse Frog (Eleutherodactylus planirostris) and Cuban Treefrog (Osteopilus septentrionalis) of the introduced species. There is a newly described/about to be described Chirping Frog species I might still need although I won't know that until I see a range map.
I will leave you with a bit more of the recording of the Spring Peepers, Southern Leopard Frogs and Pickerel Frogs from this dirty roadside ditch.
Uperoleia lithomoda, photo by Richard D. Reams (CC license)
The Stonemason Toadlet (Uperoleia lithomoda) is another small toadlet from the Top End of Australia. Like the other "toadlets" in the Australian genus Uperoleia, they are neither toads nor related to toads. They are related to other Australian Ground Frogs in the family Myobatrachidae. It is another of the many examples where the English words "frog" and "toad" fail to adequately describe the broad diversity of Anurans that are found throughout the world.
Like other Uperoleia, the Stonemason Toadlet remains burrowed underground through much of the year and only emerges to breed during the rains of the wet season. I recorded these Stonemason Toadlets calling next to the road in Kakadu National Park after some heavy rains on the evening of January 4, 2024.
I never saw the toadlets making this call, so I am once again indebted to the generosity of other photographers who allow their iNaturalist record photos to be used under a Creative Commons License. This great photo was posted by Richard D. Reams (username rreams) on his record for the species from further west in the Northern Territory.
The call of the Stonemason Toadlet sounds like the clicking of stones together, or as the common name implies, the sound of a stonemason at work. For those of use more familiar with North American frog calls, it is reminiscent of the clicking of our Cricket Frogs (genus Acris).
In this recording, you hear Stonemason Toadlets calling against a background of the raspy calls of the Desert Treefrog (Litoria rubella).
The Remote Froglet (Crinia remota) is a small frog of the Australian Top End. Unfortunately, although I have managed to record a few species of Crinia while in Australia, I have never managed to see one of the little buggers! They are tiny frogs that call from flooded grassy areas and seem to stop calling/disappear as soon as you approach or shine a light on them. 😒
So once again I am forced to rely on the generosity of others who have agreed to allow their photos to be used under a Creative Commons License. The photo above was taken by Aaron Bean (username beaniana08 on iNaturalist) and is used under the terms of the Creative Commons license he granted to iNaturalist.org.
The call of the Remote Froglet is an ascending trill, somewhat remniscent of the calls of many of our North American Chorus Frog (Pseudacris species). This chorus was calling from a grassy, flooded roadside ditch in Kakadu National Park northwest of the town of Jabiru on a rainy January night at the beginning of 2024.
