and instead are evenly spaced. Anuran species tend to have specialized morphology and biochemical functions that allow them to control the acoustic frequency and oscillations of their calls. Common morphological features of calling anuran species are highly developed trunk muscles, vocal sacs, and tympanic membranes. Calling is a very energetically expensive behavior and as such may explain why choruses and songs are relatively short in duration. Acoustic crypsis Environment The most common form of communication among anuran species is acoustic communication. This means that the main way for S. sila males to attract and communicate with females is through advertisement calling. However, predators of the species such as the frog-eating bat (Trachops cirrhosus) and frog-biting midges (Corethrella spp.) also utilize male S. sila advertisement calls to locate individuals to hunt or parasitize. This creates a trade-off between mating success and a greater rate of predation for an individual. This trade-off has influenced when and how males choose to call. Male S. sila tend to call more frequently, utilize more complex calls, and have a longer total calling period on moonlit nights compared to moonless nights as they are better able to visually detect predators when the night is relatively bright. On dark, moonless nights males tend to hide within overhanging vegetation and perform shorter, simple calls at a lower frequency. Synchronous chorus Males also exhibit a rare almost-perfect synchronicity in their calling; most anuran species use alternating signals to advertise themselves to potential mates. These synchronous choruses create an auditory illusion where potential predators are biased towards the first call of the chorus and perceive all following calls as from the same location as the leading call. This allows for acoustic crypsis by all following males, hiding their location from predators. All of this seems to also lower the ability of males to attract a female to their location, but female S. sila show no preference for the first caller and may also utilize this illusion to choose hidden males and lower their own likelihood of being caught by a predator. In fact, relaxed sexual selection by females is what allowed for the evolution of this strategy. Females also show no preference between synchronous or non-synchronous calls of S. sila males. Amplexus and egg laying S. sila females create singular basins on gravel islands within streams or alongside the riverbanks. These basins are formed during amplexus; as the male holds