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Smilisca sila Duellman and Trueb 1966

Least Concern (IUCN 3.1)
Smilisca sila
Male Smilisca sila.

Common name

Pug-nosed Treefrog, Panama Cross-banded Treefrog



Species description based on Savage (2002). Medium sized treefrog. Males to 45 mm; females to 62 mm. Males have a paired vocal sac.

Smilisca sila Adult 1 Smilisca sila Adult 2


Dorsal surface tuberculate and is gray, tan or reddish brown in coloration. Darker blotches and markings may be present, as well as white or green flecks.

Smilisca sila Dorsal 1 Smilisca sila Dorsal 2


Ventral surface creamy white. Throat (i.e. vocal sac) of males is grey, whereas throat of females is white with some small brown flecks.

Smilisca sila Ventral 1

Concealed surfaces

Posterior surface of the thigh is brownish with blue spots. Groin has similar blue spots, while the lateral surface posterior to the arm has yellow spots.

Smilisca sila Concealed surfaces 1 Smilisca sila Concealed surfaces 2

Distinguishing characteristics

Snout very short and truncated in appearance.


Iris brown with black reticulations.

Smilisca sila Eye 1


Hand and feet moderately webbed. Toes with large terminal pads.

Life history

Breeding season

Breeding occurs during the dry season (Heyer 1976). Males call from the edges of forest streams (Nunes 1988). During amplexus, females construct shallow open depressions in which to lay their eggs (Malone 2004).

Smilisca sila Breeding season 1


Small, black eggs float on surface of water (Malone 2004).

Smilisca sila Egg 1 Smilisca sila Egg 2


Although they breed in streams, tadpoles of S. sila are adapted to life in quiet pools (Heyer 1976). Bodies are fat and tails are less muscular with high tail fins, unlike more typical stream-dwelling species (Heyer 1976).

Smilisca sila Tadpole 1 Smilisca sila Tadpole 2 Smilisca sila Tadpole 3 Smilisca sila Tadpole 4 Smilisca sila Tadpole 5

Ecology behavior and evolution


Tadpoles are scrapers and chewers, mostly eating algae from the surface of rocks and submerged plant matter in stream pools (Heyer 1976).


Adult Smilisca sila are depredated by bats (Trachops cirrhosus; Tuttle and Ryan 1982).


A low squawk, usually followed by one or more rattling secondary notes (Ibanez 1991). Males also produce aggressive calls (Ibanez 1991).

Smilisca sila Call 1

Behavior and communication

Smilisca sila change calling behavior in response to availability of light in the environment (Tuttle and Ryan 1982, Nunes 1988). Frogs call more and produce more complex calls on moonlit nights, and are also less likely to call from concealed sites, such as under leaves (Nunes 1988). Tuttle and Ryan (1982) suggested than moonlight allows the frogs to detect and avoid bat predation. Males also prefer to call near waterfalls (Tuttle and Ryan 1982). The frequency of waterfall noise completely overlaps with that of the calls of S. sila, thus potentially further hindering detection by bats (Tuttle and Ryan 1982). Finally, frogs synchronize calling (Tuttle and Ryan 1982, Ibanez 1991), which lessens chances of bat predation because bats are less likely to respond to synchronized calls (Tuttle and Ryan 1982).


Smilisca sila has a much shorter latency to response to calls of other males than many of species of frogs thus studied (Ryan 1986). Ryan (1986) suggested that use of a different neural pathway decoupling call detection and call recognition may contribute to call overlap in this species.

Taxonomy and systematics


  • Kingdom:Animalia
    • Phylum:Chordata


Duellman and Trueb 1966


Hyla sila

Type locality

a small stream at north edge of the village of El Volcán, Chiriquí, elevation 1280 meters (Panama)

Habitat and distribution


Lowland rainforest to 970 m.


Colombia, Costa Rica, Panama


Smilisca sila distribution
Distrubution map (IUCN)


Duellman, WE and L Trueb. 1966. Neotropical frogs, Genus Smilisca. University of Kansas Publications of the Museum of Natural History 17: 281-375.

Duellman, WE. 1968. Smilisca sila. Catalogue of American Amphibians and Reptiles 63: 1-2.

Duellman, WE. 1968. Smilisca. Catalogue of American Amphibians and Reptiles 58: 1-2.

Duellman, WE. 1970. The Hylid Frogs of Middle America. Monographs of the Museum of Natural History University of Kansas.

Duellman, WE. 2001. The Hylid Frogs of Middle America. 2nd ed. Society for the Study of Amphibians and Reptiles, Ithaca, New York.

Dunn, ER. 1931. New frogs from Panama and Costa Rica. Occasional Papers of the Boston Society of Natural History 5: 385–401.

Heyer, WR. 1976. Studies in larval amphibian habitat partitioning. Smithsonian Contributions to Zoology 242: 1-27.

Ibanez, DR. 1991. Synchronized calling in Centrolenella granulosa and Smilisca sila (Amphibia: Anura). Unpubl. PhD dissertation. University of Connecticut, Storrs.

Ibáñez, R, F Solís, C Jaramillo, and S Rand. 2000. An overwiew of the herpetology of Panama. In: Johnson, J.D., Webb, R.G. and Flores-Villela, O.A. (eds), Mesoamerican Herpetology: Systematics, Zoogeography and Conservation, pp. 159-170. The University of Texas at El Paso, El Paso, Texas.

Jaslow, AP. 1982. Factors affecting the distribution and abundance of tadpoles in a lowland tropical stream. Unpubl. PhD dissertation, University of Michigan, Ann Arbor.

Jungfer, K-H. 1988. Froschlurche von Fortuna, Panama II. Hylidae (2), Centrolenidae, Dendrobatidae. Herpetofauna 10: 6-12.

Malone, JH. 2004. Reproduction in Three Species of Smilisca from Costa Rica. Journal of Herpetology 38(1): 27-35.

Martin, AA and GF Watson. 1971. Life history as an aid to generic delimitation in the family Hylidae. Copeia 1971(1): 78-89

Nunes, VS. 1988. Vocalizations of treefrogs (Smilisca sila) in response to bat predation. Herpetologica 44: 8-10.

Rand, AS and CW Meyers. 1990. The herpetofauna of Barro Colorado Island, Panama: an ecological summary. In: Gentry, AH. Ed. Four Neotropical Rainforests. Yale University Press, New Haven, Connecticut.

Ruiz-Carranza, PM, MC Ardila-Robayo, and JD Lynch. 1996. Lista actualizada de la fauna de Amphibia de Colombia. Revista de la Academia Colombiana de Ciencias Exactas, Físicas y Naturales: 365-415.

Ryan, MJ. 1986. Sychnronized calling in a treefrog (Smilisca sila): short behavioral latencies and implications for the neural pathways involved in call perception and production. Brain, Behavior and Evolution 29: 196-206.

Savage, JM. 2002. The Amphibians and Reptiles of Costa Rica: A Herpetofauna between two Continents, between two Seas. University of Chicago Press, Chicago.

Tuttle, MD and MJ Ryan. 1982. The role of sychronized calling, ambient light, and ambient noise, in anti-bat-predator behavior of a treefrog. Behavioral Ecology and Sociobiology 11: 125-131.

Additional resources

Audio Files

Vocalization of Smilisca sila