Smilisca sila Duellman & Trueb, 1966

Adult Size

Adult Smilisca sila have a maximum snout–vent length of 45 mm (1.8 in) for males and 62 mm (2.4 in) for females.

Dorsal Skin Characteristics

Their dorsal (upper) skin is tuberculate (bumpy) in texture, and has a gray, tan, or reddish-brown base color; individuals may also have white or green flecks, plus darker blotches and markings.

Ventral Surface Color

The ventral (belly) surface is creamy white.

Vocal Sac Differences

Males have a paired gray vocal sac, which they use to produce their characteristic choruses, while females have a single white vocal sac with brown flecks.

Limb Underside Markings

The underside of the thighs and groin is brown with blue spots, and the underside of the arm has yellow spots.

Iris Appearance

Their irises are brown with a black net-like pattern.

Toe Structure

Both front and back toes are webbed and end in large toe pads.

Sister Species Morphology Comparison

Adult Smilisca sila are very similar in morphology to its sister species, Smilisca sordida, but have a flatter snout and bumpier skin.

Tadpole Body Morphology

Tadpoles of this species have a relatively round body, weak muscles, and broad, short tails adapted for living in small ponds.

Tadpole Mouthparts

They have mouthparts specialized for scraping and chewing food.

Species Distribution

Smilisca sila occurs in the lowlands of southwestern Costa Rica, Panama, and northern Colombia.

Habitat Preferences

It prefers transitional zones between wet and dry lowland tropical forests near shallow rocky pools and stream banks, but can also be found in secondary forest, and sometimes in relatively open areas.

Elevation Range

This species is found at elevations ranging from 10 to 970 m.

Breeding Season Timing

Breeding happens during the dry season from January to April at low elevations; at high elevations, breeding may occur during the rainy season.

Female Egg Laying Sites

Females prefer to breed and lay eggs on gravel islands or banks alongside first-order streams.

Male Calling Positions

Males typically call from positions alongside streams that have ambient noise and overhanging vegetation, which can mask their calls from predators and provide hiding space if needed.

Tadpole Habitat

Tadpoles live in clear pools and slow-moving water, staying near the bottom.

Acoustic Communication Function

Acoustic communication is the most common form of communication among anurans, and for male Smilisca sila, it is the main way to attract and communicate with females through advertisement calls.

Call Exploitation By Predators

However, predators of this species – including the frog-eating bat Trachops cirrhosus and frog-biting midges of the genus Corethrella – also use these advertisement calls to locate Smilisca sila individuals to hunt or parasitize them.

Mating-Predation Trade-off

This creates a trade-off between individual mating success and higher predation risk, which has shaped how and when males choose to call.

Moonlit Night Calling Behavior

Males call more often, use more complex calls, and have a longer total calling period on moonlit nights than on moonless nights, because they can detect predators visually more easily when the night is bright.

Moonless Night Calling Behavior

On dark, moonless nights, males hide in overhanging vegetation and produce shorter, simpler calls at a lower frequency.