The Dwarf Glass Frog (Teratohyla spinosa), as the name implies, is a small Centrolenid frog found in lowlands and tropical foothills on the Atlantic versant of Costa Rica and Panama, then into eastern Panama and the foothills of western Colombia and Ecuador. There is apparently a disjunct population in eastern Honduras and there are recent records from Nicaragua.. The curious gaps in range in most of Nicaragua and central Panama may represent under-sampling or may be the indication of the disappearance of intervening populations? This is one of the species that appears to be increasing in numbers again after a population decline in the last few decades associated with chytrid infections.
We found more than a dozen of this small frog calling from leaves along a rocky stream at the Costa Rican Amphibian Research Center. Some were calling many meters away from the edge of the stream. The individual in the photo above was photographed and recorded calling from the leaf it is sitting on, a meter or so above the ground and around 5 meters away from the stream.
The call of this species is best described as a high-pitched, buzzy "creek-creek-creek" with a carrier (dominant) frequency around 5.5 to 7 kHz. In the recordings I was able to capture, the call was a series of five creek sounds that descended in pitch towards the end. I also noticed that the fourth creek was shorter than the others, almost a sort of grace note. So the call could be transliterated as "creek-creek-creek-cre-creek".
Here is a spectogram of one of that series of calls. You can see the "trilled" nature of the creeks, the shorter fourth creek, and how the frequency of the calls decreases at the end.
Dwarf Glassfrog calling
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© Chris Harrison 2025
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