threatened by common hazards to amphibian species such as habitat loss caused by agriculture, illegal crops, pollution, pesticides, logging, and human settlement. The species occurs in many protected areas, such as the Parque Nacional Carara in Costa Rica and Barro Colorado Island in Panama. Population structure, speciation, and phylogeny Close relatives and hybridization The closest relatives of S. sila are the other Smilisca species, S. baudinii, S. manisorum, S. phaeota, S. puma, and S. sordida. The Smilisca clade as a whole consists of the Anotheca, Diaglena, Smilisca, and Triprion genera, and is weakly related to the Hyla and Isthmohyla clades. The basin construction reproductive model of S. sila is shared with the closely related species Smilisca sordida and is a synapomorphy character for the two species. It is not found in the other Smilisca species. Interspecific amplexus has been observed between male S. sila and male Strabomantis bufoniformis on a female S. bufoniformis as well as between a male S. sila and Craugastor fitzingeri individual. These events may show a potential lack of selectivity by S. sila males. Behaviour Diet S. sila tadpoles possess scraping mouthparts and are substrate feeders of algae and plant matter within their ponds. Although S. sila breeds during the dry season, periods of rain may connect small ponds and allow the tadpoles to travel between them, expanding their access to food resources. Mate calling Panama cross-banded tree frogs are nocturnal. Breeding takes place during the dry season when males call from the edges of forest streams. S. sila males utilize variable complex calls to attract females influenced by factors such as predator presence, other males, ambient noise of surroundings, and relative darkness of the night. The advertisement calls of S. sila, calls produced during breeding season for the purpose of attracting mates, fall under Guild H of the proposed guild classification system for anuran calls. These calls are complex and modulated by frequency, composed of at least two structurally distinct notes and a significant change in dominant frequency throughout the call. Guild H represents only 2.3% of the 1,253 anuran species categorized, making it relatively rare. The dominant frequency of S. sila calls is 1915 Hz. Single notes of the male S. sila advertisement call last for approximately 0.16 seconds and calls may have as many as four notes. A male of the species averages 1.7 calls per minute. Males do not aggregate alongside streams,