All the "snouted treefrogs" in the genus Scinax are known for their pronounced rostrum which is where they get their common name. But Boulenger's Snouted Treefrog (Scinax boulengeri) wins the prize for the species I've seen so far. It's duck bill is very strange looking.
This species of treefrog is found in lowland and premontane rainforest and rainforest edges from Nicaragua south into northwestern Ecuador. Not only is S. boulengeri larger than the other northern Scinax species (S. staufferi and S. elaeochroa), but it also has much more tuberculate, "warty" skin. It looks much more like the some of the South American Scinax species than it does its immediate neighbors.
The call of this species surprised me a bit. I was expecting more of a "dry" unmusical call like we hear from S. elaeochroa and S. staufferi, but S. boulengeri instead has a louder vocalization that reminds me of some of the larger treefrog species. (I should add that I did not see these frogs calling, but recorded these calls with an unattended recorder late at night. I did see Scinax boulengeri at this pond earlier.)
The call of this species is described as a loud "wraak" and to my ear it has sort of a nasal hint to it (not surprising looking at the frog 😉). In my recordings, I found that when the species was chorusing with multiple individuals, their call became a two part "raw-kuh" with a longer first syllable.
Here is a recording of some Boulenger's Snouted Treefrogs calling from an articial pond at the edge of a premontane rainforest in the Gulfo Dulce region of Costa Rica in January 2023. (The dry "wreek" trill in the background is the Harlequin Treefrog, Dendropsophus ebraccatus)
This recording is available for download from my iNaturalist record.
When you take a look at just a short section of that recording (about 5 seconds in) you hear two frogs calling back and forth. As is the case with most anurans, when two individuals are calling sequentially they will alter the pitch of their calls slightly to be heard over the other. So you hear a sort of alternating, two syllable "rih-kuh, raw-kuh, rih-kuw, raw-kuh, rih-kuh" sound. In the spectrogram you can see the buzzy character (the wavy lines) and the short abrupt second syllable clearly.
I was very happy to see and record this species when in Costa Rica this year. I love Scinax and this has to be my favorite Scinax so far. What a cool frog!
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© Chris Harrison 2023
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