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Scinax rostratus from iNaturalist user Fundacion ProAves |
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.
Caracas Snouted Treefrogs calling in a chorus of other species.
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.
I uploaded that recording as "Frog species" onto iNaturalist and once again, Roberto Ibanez identified the call for me.
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.
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| Scinax rostratus range map from the IUCN Redlist Database |
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.
So, once again, I got another new lifer frog recording by uploading a mystery and having iNaturalist users help me out!
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© Chris Harrison 2026
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.
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