surface of the water to form a monolayer. Forced amplexus is rare. Occasionally, another male will attack an amplexed pair to separate them, and the attacking male occasionally then mates with the female. In general, mating success in this species is highly skewed, as a minority of calling males are able to mate successfully with a female. The best predictor of male mating success is chorus tenure, or the number of nights that a male has participated in the calling chorus. Parental care Parental care in this species takes the form of clutch guarding and nest building for oviposition. These nests are water-filled depressions in the ground, and their structure varies based on the environment in which they are built. In Panama’s canal zone, where the species breeds along a river, all males build their own nests. However, in the Costa Rican population in a small swamp of cattle pasture, only a fraction of males built nests, as males would occupy small puddles or cattle footprints as nests. They would only build nests by pushing vegetation down and away when the other depressions were not available. Thus, this species displays facultative nest construction, as nest construction is a very time and energy consuming activity (it takes males one night to build a nest, during which the male cannot call for mating), so individuals of this species would take advantage of local conditions that decrease nest construction time and sometimes will reuse existing nests. Males of this species do not generally share nests, but abandoned nests will be reused. For clutch guarding, males will sit on a perch near or immediately above a freshly laid egg monolayer, remaining silent except for infrequent territorial calls. The males likely guard clutches against intruding males who could disrupt the surface tension of the egg monolayers, causing the clutches to sink and the eggs to die. Males clutch guard for one or two nights, but never longer, which is reasonable given the cost of not advertising. In addition, males will leave their clutch but return to guarding position when territorial or advertisement signals are broadcast near the clutch, indicating the presence of rival males. Interestingly, clutch guarding behavior is solely observed in the Panamanian population of H. rosenbergi, not the Costa Rican population. Social behavior Males of this species are split into intruder and resident categories, depending on if the male occupied a nest from