One of the constant distractions I get when out trying to record frogs is creatures that sound like frogs. I'm already discussed a couple of sneaky birds like the Lesser Nighthawk and Carolina Wren and a frog-impersonating Gray Fox, but the most common "false alarm" calls I get distracted by is the short frog-like trill of the Northern Mole Cricket (Neocurtilla hexadactyla).
Northern Mole Cricket photo by Jordan Perrett Used under Creative Commons License granted in this iNaturalist record
This fossorial cricket lives in the eastern half of North America all the way down through the Panamanian Isthmus into South America. And it has closely related species occurring beyond that range as well.
Obviously, no one is going to confuse the appearance of this cricket with a frog. The problem with this cricket is its call and habits of calling. This cricket will call from damp grassy areas buried deep under the grasses. This is often where species of Pseudacris and other grassland amphibians will call. So on more than one occasion I have pointed my microphone at one of these little arthropods and pressed record, only to remember I'd been fooled again! (Not that there is anything wrong with recording insects, I just don't need any new hobbies! 😉)
Here's the call of a Northern Mole Cricket calling from a clump of dense, damp grass in Chambers County, Texas -
Compare that Mole Cricket call to the raspy trill of the Spotted Chorus Frog (Pseudacris clarkii), a species which calls from the same damp/flooded grassy areas -
It isn't just me that gets confused by these small Orthopterans. I spend considerable time identifying frog calls on iNaturalist and this species is one of the more common misidentifications I find. They are tricky. Not only do they sound like they might be a frog, they call from areas where you would expect a frog!
So next time you are out in a damp grassy area and think you hear a frog.....stop and ask yourself..."Have I been fooled by the Northern Mole Cricket?" For me, the answer has been yes more times than I've like to admit! 🤣
On another post, I made the comparison between the two species of Gray Treefrog (Dryophytes versicolor vs Dryophytes chrysoscelis). But there is a third species of treefrog that is easily confused with those other two, the nearly identical looking Bird-voiced Treefrog (D. avivoca).
In Texas, we don't really have to worry about this comparison because there has never been a documented record of Bird-voiced Treefrog found in the state. They get really close - there are records from just north of the Red River in southern Oklahoma and in southeastern Arkansas. The closest records are within 13 miles of the Texas border, but no one has ever been able to document one in Texas. I made a trip up to the border area a few years ago after some rains listening intently for the peeping whistles, but couldn't find any. If I lived closer, this is a project I would work on more often!
But if you did find one, how would you know? They are very similar looking to both Gray Treefrog species and everywhere Bird-voiced Treefrogs occur, at least one of the Gray Treefrogs could also be found.
For the purposes of discussion hereafter, I will refer to both Gray Treefrog species (D. versicolor and D. chrysoscelis) as the "Gray Treefrogs" to keep it simple.
Here's a couple of clues that help distinguish them:
Size
the Bird-voiced Treefrog is slightly smaller, roughly 2.5–5 cm (1–2 in)
the Gray Treefrogs are slightly larger, 3.2–5.1 cm (1.3–2.0 in)
Clearly you can see that although Gray Treefrogs are larger than Bird-voiced, there is some overlap in size making this less helpful. And there is sexual dimorphism in treefrogs - females are larger than males. So a female Bird-voiced and a male Gray Treefrog could be roughly the same size.
At the same given body length, the Gray Treefrogs are generally stockier and heavier-bodied than the slightly more slender Bird-voiced.
Skin texture
Bird-voiced Treefrogs have skin that is relatively smooth and fine-grained compared to the bumpier skin of gray treefrogs.
Gray Treefrogs tend to have more pronounced tuberculate skin.
Again, this character has enough overlap to not be diagnostic by itself. Some Gray Treefrogs have pretty smooth skin.
Coloration of thigh and groin area
This is probably the most useful diagnostic visual character. Both of these species have contrasting color mottled on the rear of their thighs and the surrounding area.
In Bird-voiced, the background to the mottled patches is lime green, sometimes greenish-yellow with darker mottling
In the Gray Trefrogs, the background color to the mottled patches is bright orange-yellow.
You can just see the pale greenish-yellow on this Bird-voiced Treefrog from Arkansas,
and here is the orange-yellow background of the Gray Treefrog (in this case, Cope's Gray Treefrog, D. chrysoscelis).
Habitat
The Bird-voiced Treefrog has a smaller range and it is generally associated with river swamps and closely associated backwaters, mainly along the Gulf Coast of the US from South Carolina to Louisiana and then up the Mississippi river valley to southern Illinois. It has a very localized distribution with apparently disjunct populations, probably left over from the destruction of its habitat.
The Gray Treefrogs are found throughout the eastern 1/2 of the North America as far north as Canada. They are found in a variety of habitats including woodlands, swamps, grassy savannahs, and scrubby brush along waterways. They are very flexible and have adapted well to human habitats like backyards where there is water.
Voice
As you would expect on my blog devoted to frog calls, the last and best characteristic to tell the species apart is by call.
The call of the Bird-voiced Treefrog is a series of rapid whistled calls repeated a dozen or more times. Here's one calling from just 50 miles NE of the Texas border in Arkansas.
The call of the Gray Treefrogs is a whistled trill call. The difference between the two species, Dryophytes versicolor vs D. chrysoscelis, is the rate of the trill. The Gray Treefrog (D. versicolor) has a slower pulse frequency to its trill (12-34 pulses per second). Here is a Gray Treefrog call from near Palestine, Texas.
The call of the Cope's Gray Treefrog (D. chrysoscelis) is a more rapid trill (34-60+ pulses per second), giving it a drier, buzzier character than the bird-like character of the Gray Treefrog (D. versicolor).
So in the narrow area where the Bird-voiced Treefrog overlaps with the Gray Treefrogs, the best way to tell them apart is by listening to their calls. Hopefully in the near future, I will be able to find the Bird-voiced Treefrog calling in Texas!
Emerald Glassfrog (Espadarana proseblepon) Canopy Lodge, Anton Valley, Panama
I decided after coming back from the Herpetology at the Isthmus tour in Panama this summer to update and clean up my lifelist. I recorded 22 species of anuran in Panama during (and around) that trip. I added one, make that TWO new species and got better recordings of several other species for which my previous recordings were pretty poor.
and the other species I recorded included: Striped Rocket Frog (Allobates talamancae) Red-webbed Treefrog (Boana rufitela) Sabinal Frog (Leptodactylus melanonotus) Harlequin Treefrog (Dendropsophus ebraccatus) Tatayo's Glassfrog (Hyalinobatrachium tatyoi) Túngara Frog (Engystomops pustulosus) Mexican White-lipped Frog (Leptodactylus fragilis) Panama Snouted Treefrog (Scinax altae) Fitzinger's Robber Frog (Craugastor fitzingeri) Yellow Treefrog (Dendropsophus microcephalus) Savage's Thin-toed Frog (Leptodactylus savagei) Masked Treefrog (Smilisca phaeota) Panamanian Granular Toad (Rhinella centralis) Rosenberg's Gladiator Frog (Boana rosenbergi)
I also got a new species for Panama, the Whistling Grass Frog (Leptodactylus fuscus) which I had only previously recorded in Trinidad. When I recorded it, I called it the Mexican White-lipped Frog (L. fragilis) which sounds very similar and was also calling in the field with the Whistling Grass Frog. I will probably need to make a comparison post to hear how similar their calls are!
So as I reach midyear in 2026, my recording lifelist is now at 145 species, in 58 genera, and 15 families. I thought I was at 144 earlier, but I have a few species in here I may not have recorded (i.e. my recording may be a different species - e.g. Eleutherodactylus portoricensis, Smilisca manisorum). Excuses for more travel?
Can I get to 150 species this year? It will be tough, but worth a shot!
Scinax rostratus from iNaturalist user Fundacion ProAves Used under Creative Commons licenses granted to this iNaturalist record
I got another new frog species that I've never seen, thanks once again to Roberto Ibanez on iNaturalist (ribanez). I had recorded some frogs calling along a flooded roadside south of the town of Chepo in Central Panama. While I was recording some other species, I came across this buzzy trill that I had never heard before. There were clearly two frogs calling back and forth from the grassy edge of the flooded area, but I had no way of getting over there to find them.
When I got home with that
recording, I made a few comparisons with species I thought it might have
been, but when there are more than 150 species of frogs in Panama and
many of those don't have their calls well documented, it is pretty tough
to find a match without having some idea where to start looking.
In hindsight, the call does remind me of the other larger Scinax species (S. boulengeri) that I have recorded, so it makes sense.
The Caracas Snouted Treefrog (Scinax rostratus) is one of the "big" snouted treefrogs (although only a couple of inches long). Like many of the larger Snouted Treefrogs (Scinax sp.), this treefrog shows the fringed edges to its legs and rostrum which presumable help it blend in on branches and leaves when it is resting. This species ranges from the lowlands of central Panama into northern Colombia then east across the lowlands of Venezuela and the Guianan shield and down into northern Brazil.
The call of this species is described by Bang, et al. (2017) as a series of multi-pulsed notes with a duration of 2-10 seconds with a mean call duration of 770 milliseconds (range of 138-3106 ms). In a series of calls, the authors note that the last calls are generally shorter than the first ones. The pulses get louder in each series and then decay towards the end.
In my recording, the frogs start out with a couple of long, loud calls lasting 1100 to 1700 milliseconds, then "fade" into a series of short calls lasting around 225 milliseconds. My recordings seem to match the description of Duelmann (1972) with a pulse rate of ~55 pulses per second. Duelmann notes that the carrier frequency includes a peak around 3050 Hz, and my recording matches that with a peak around 3199 Hz.
Here's a section of spectrogram of a series of the calls I recorded that night. You can see the "buzzy trills" that are repeated a few times as a long call, then "fading" into a series of shorter pulses.
And the recording that includes the section of that spectrogram. You hear a few long trills followed by the shorter ending trills.
Bang, Davi & Giaretta, Ariovaldo. (2017). Filling a gap in the distribution of Scinax rostratus (Peters, 1863) (Anura, Hylidae) in northern Brazil, with further data on its advertisement call. Check List. 13. 1-4. 10.15560/13.3.2150.
Duellman, W.E. 1972. South American frogs of the Hyla rostrata group (Amphibia, Anura, Hylidae). Zoologische Mededelingen 47:177–192.
Getting a recording of Leaf Litter Toads calling is a bit of a surprise. They aren't rare, I have traveled to their native range many times, I have seen them many times,...but for some reason I've never heard them calling before.
Leaf Litter Toad (Rhaebo haematiticus) San Carlos, Costa Rica
My last night at Canopy Lodge in Anton Valley, Panama, I was walking over towards the front of my room when I heard a mysterious "peeping" coming from a little creek at the far end of the lodge. It was just getting on dusk and had rained during the afternoon. I have recorded seven species at the Canopy Lodge garden in my previous trips there, but this was something new? I didn't know what it was.
It was too loud and fast for a "tink frog" species (Craugastor or Pristimantis) and too loud and constant for any of the "Rocket Frogs" (Colostethus, Allobates or Silverstonia). I made a recording of the fast peeping with my phone and then went back to my room to get my better microphone and a flashlight to find the singer and get a better recording. After getting my gear and walking back there (3 minutes later?), the frogs had fallen silent and I couldn't see them.
To be fair, I had a bit on an issue trying to see the creek clearly because I stumbled across this creature. This is echis*, or vibora echis, the local common name for Bothrops asper. This is an infamous widespread venomous species with many different common names throughout it large range**. No matter what you call it, this was a distraction because it was right next to a walkway to people's rooms along a sidewalk that wasn't well lit. If I left it there, it would be killed by the grounds crew the next morning. Because I was there on a herpetology tour, we were experienced enough and equipped to capture and relocate it to a nearby patch of forest along a creek.
"Echis" (Bothrops asper) that distracted me from the task at hand
Anyway, back to the toads....but they had fallen silent by the time we got the snake moved. 😢
But at least I had my phone recording. So you will hear a cleaned up version of that.
The Leaf Litter (or Truando) Toad is a medium sized toad of tropical rainforests from the Atlantic versant of Honduras and Nicaragua, down through the lowlands of Costa Rica, Panama and into Colombia.
The Leaf Litter Toad is a handsome species, as toads go. Their back is a warm pastel brown and there is a boldly contrasting dark brown stripe along the side of the head continuing on to middle of the body. Their belly and around the hind legs is suffused with an salmon or orange wash. It is quite a surprise meeting this "toad" if you are more familiar with the mostly drab toads of the northern hemisphere.
The call of this toad is a series of loud peeps. It reminds me of the "chick-like" peeps of the Oak Toad (Anaxyrus quercicus) of the southeastern US, but this species is larger, so the peeps are louder and are repeated many times in succession (rather than the single peeps of the Oak Toad).
The call is a series of these upward slurred peeps at around 2.4kHz. When I heard these toads, they were repeating about 7 peeps per second for around 10 seconds per call. This rate and possibly the frequency would be temperature dependent. But in the relatively narrow temperature range of the lowland neotropics, it may not vary much?
And here, for your listening pleasure, is the call of the Leaf Litter Toad.
* There is a possibility of some confusion around this common name. While "echis" is the Spanish common name used in most of Panama for this well-known serpent, it is also the genus name for a group of Saw-scaled Vipers and Carpet Vipers of northern and central Africa, the Middle East, Central Asia and western India. The Panamanian name is a reference to the letter X (echis in Spanish), a reference to the X-like patterns seen on their backs. They are not closely related to the vipers of the Old World.
** A commonly used "English" name for this species is Terciopelo. This name is the Costa Rican name for this species, and since most English speaking people's first (only) exposure to this species comes on tourist visits to that country, that name "sticks". But it is known by several other Spanish common names throughout its range (including "echis"). Occasionally this species is referred to as the "Fer-de-Lance" because people are familiar with that name. However, that name is technically reserved for a species of lancehead viper found only on the island of Martinique (thus the French name!). The name "Central American Lancehead" is probably a much better name for this widespread snake.
Common Tink Frog (D. diastema) trying to impress a female that has approached his leaf. Near Aguas Zarcas, Costa Rica.
Tink Frogs in the genus Diasporus are named for their metallic "tink" calls.
The problem I have is as follows:
This is the widespread Common Tink Frog (Diasporus diastema) for which the species gets its name. This was recorded in north-central Costa Rica. Anyone in the area will confirm this as a "Common Tink Frog". Notice it is more of a dry "tick" than a metallic "tink".
Compare that tink to this more metallic sound that I recorded in southern Costa Rica. Again, people in the area will tell you this is the Common Tink Frog.
OK, not a profound difference,....but different. Both of these recordings are consistently identified as Diasporus diastema by iNat identifiers.
But is it really the same species? I'm not convinced. I've listened to a LOT of frog calls over the years, and I wonder if those two calls are coming from different species.
But wait, there's more.....
Here's another recording (from Panama this time) of some frogs that "people in the know" have identified as D. diastema on my recordings. Notice how the call is no longer a percussive "tick" or "tink" but now is a fast, upward, whistled call...
Now enter the confusion, the Yellow-dyer Tink Frog (Diasporus citrinobapheus). This species is very similar overall to the Common Tink Frog, but is a bit less "tuberculate" and has the odd character of staining your skin yellow when they are handled.
I know this preceding call was a Yellow-dyer Tink Frog because we caught the individual that was calling and it stained our skin yellow!
Yellow Dyer Tink Frog who had the upward whistled "tink" Anton Valley, Panama
So now listen to this recording from Panama. If you listen carefully, you hear the upward whistled tink AND the more dry tick sound (in the background). The upward whistled calls sound like the Yellow-dyer, but a well-known expert on frogs from Central Panama told me that call is the Common Tink Frog, and the higher pitched tink is a different Diasporus species (they didn't ID it for me though).
Confused? So am I.
Either the dry tick, metallic tink and the upward whistled call are all made by the same species AND a related species makes the upward whistled call as well even though they overlap in range or....or these identifications are all wrong?
You might be inclined to suggest that the calls are identical and the way to learn to tell their calls apart is to catch them calling and identify them visually. The problem is many of these small frogs are very similar looking and difficult to ID even in hand.
Also, it is very hard to find a calling tink frog because the short, sharp and sporadic tinks don't let your brain home in on the location of the caller very well. And they call from on top of leaves which has a sort of ventriloquist effect in the forest.
Then there is the hypothesis that both species (D. diastema and D. citrinobaphus) have overlaps in their calls and that D. diastema sometimes sound different, occasionally like the other species. After all, there is variation is species (Darwin, 1859)
But I have a more fundamental problem with this idea. Frog calls are a main mechanism of pre-zygotic reproductive isolation in frogs. They have to sound different than other species, at least to females of the same species. If the males are making two different calls that sound like the calls of other sympatric species, how would females be able to tell them apart?
I think the real answer is that many people, including experienced people, are misidentifying these tink frog calls because they do sound similar. Add to that the fact that many areas only have one "tink" frog so people just assume what they are hearing must be the Common Tink Frog (D. diastema), after all, it is what they commonly hear?
I may be wrong, and maybe I'm the only person who doesn't get how this upward whistled tink, the metallic tink and the drier, shorter tink can all be the same frog call that matches the call of other similar species that overlap in range/habitat? If I'm wrong about this, I would love to be corrected, but I'm going to have to be able to hear the difference.
Just to add to the fun, there are other frog genera that have tink-like calls and they can increase your confusion about the source of "tinks".
Here is the Lesser Antilles Robber Frog (Pristimantis urichi) recorded in Trinidad:
And then we have to consider that many of the glassfrogs (Centrolenidae) also have high pitched peep type calls that can sound similar at night in the field.
Here is Tatayo's Glassfrog (Hyalinobatrachium tatayoi) from Panama. It is noticeably higher pitched, but can be confusing at first....
And here's its cousin the Yellow-flecked Glassfrog (Sachatamia albomaculata), again from Panama.
And another, the Chiriqui Glassfrog (Teratohyla pulverata), this one from southern Costa Rica.
And then there are the various small "Rocketfrogs" in the genera Silverstoneia, Colostethus and Allobates that can have repeated "tink" or tick type calls
Here's the Rainforest Rocketfrog (Silverstonia flotator), from Panama where several "tink" frogs also occur. Fortunately, these Rocketfrogs usually call during the day unlike the tinks.
And these are just the species I have recordings of! There are dozens of other species in multiple genera that make this peeping sound.
So if you hear a tink in the night in Central America, you might be hearing a Tink Frog....or maybe not?
I guess I need to make another trip down to Panama/Costa Rica and record and
chase down these individual calling frogs. I'm sure it is a journey I
will have to make alone. I don't see anyone else being interested in
making the trip down to Central America just to waste time on the most common,
widespread frog species of these tropical forests ignoring all the other "cool" stuff. 🤣
There are a number of neotropical frog species that only get into the United States in southern Texas. Most of these species, I have seen and recorded multiple times in Texas as well as Mexico and Central America.
But there is one species that has cursed me....the Mexican White-lipped Frog (Leptodactylus fragilis). I have seen and recorded this frog on multiple occasions in Mexico, Costa Rica and Panama. It is not a particularly hard species to find or record (although they do call from burrows in the ground!).
But for some reason, on the dozen or more trips I have made to far south Texas to get a recording of this species, I have failed every time. Other people I know are surprised by this. They aren't rare, and I know the right locations and habitat...so why haven't I found one in Texas?
Well, in May 2026 it rained in the Rio Grande Valley in the White-lipped Frog location I knew. I was not very optimistic, but I made the 4 hour drive down there anyway. When I got to the recording site, I did an afternoon "drive-by" since I know this species will call during the day in the tropics. No luck.
I came back after dark and the frogs were really calling up a storm. I got several south Texas specialities, like Mexican Burrowing Frog (Rhinophrynus dorsalis), Sheep Frog (Hypopachus variolosus) and Giant Toad (Rhinella horribilis).....but I didn't hear any white-lips! So I chalked it up as another fail.
When I got home the next day, I happened to look on iNaturalist to see what another person I know had heard. I knew he was down in the same area (actually as it turns out, on the same road!). I was crushed when I saw, among his recordings, several recordings of Mexican White-lipped Frogs.
So I decided to go back and carefully examine my recordings. I filtered out the noisy Mexican Burrowing Frogs and Western Narrow-mouthed Toads. I stared at each second of the spectrogram....and then I found it. A single call by a Mexican White-lipped Frog....from Texas!! The call was drowned out by the larger and louder species around it, but with a lot of creative filtering and trimming, I finally was able to capture a recognizable few seconds of their sharp upward whistles.
Here's the lousy recording! It is highly filtered and not very long....but it counts!
After finding this one calling, I went back through all my recordings that night and managed to hear a few more among the din produced by the bigger species.
I still need to go down there and get a decent recording, but at least for now it is on my Texas recording lifelist after nearly a decade of trying to get it!
So that puts me at 39 of the 44 species that are possible in Texas.
I still need:
Houston Toad (Anaxyrus houstonensis)
American Toad (Anaxyrus americanus)
Greenhouse Frog (Eleutherodactylus planirostris)
Pig Frog (Lithobates grylio)
and the west TX form of the Chirping Frog (Eleutherodactylus) whose name is still being worked out.
As is so often the case, I got a new frog species without any rigorous research or clawing my way through the swamp to find my target. Instead, I was standing next to a road birding and pointed my recorder out into the edge of a wooded grassy savanna where I heard this sound. I uploaded my mystery call to iNaturalist, and lo and behold (6 years later), someone finally identified it - the Forest Chirping Frog (Adenomera hylaedactyla)! So a new species and a new genus!
And once again, it is a recording of a species I have never seen, so I will borrow this wonderful photo from iNaturalist user Sebastian2 under the Creative Commons license he granted when uploading to iNaturalist.
The Forest Chirping Frog is a small frog with a loud call. It is found throughout the Amazon Basin in South America, although I recorded mine in the Aripo Savannah area of Trinidad. Looking at the distribution of iNat records for the species, it appears to occur throughout the Amazon basin and in a wide variety of habitats.
Adenomera hylaedactyla range map from the IUCN redlist
This is another of the many frogs that make chirping or tink calls. As I searched for other recordings of this species for comparison, I noticed this species seems to sound different based on the recording distance to the frogs and the quality of the recording.
Many recordings I hear on iNaturalist.org or Xeno-canto.org sound like a short chip or peep, similar to other "chirping frogs". However, my recording and many others I heard online sound more like a squeaky, raspy "creek" sound. That may be due to the fact that I was reasonably close to this frog and was using a shotgun microphone?
It has become an annual tradition to upload my recording lifelist early in the spring to add any species I added last year. I didn't get any new ones over the Christmas holidays in 2025 since I was in New Zealand (not an easy spot to record frogs!). But I did add a new lifer in early 2026 when one of my frogs from Trinidad in 2018 was identified on iNaturalist as Adenomera hylaedactyla by another iNaturalist user.
So as the season begins in 2026, my recording lifelist is now at 143 species, in 57 genera, and 15 families.
Can I get to 150 species this year? Headed back to Panama, so....maybe?
