Simple SummaryIn this study, we attempted to identify the seasonal pattern of reproductive emergence in the Japanese tree frog (Dryophytes japonicus). Individuals that emerged early in the breeding season tended to have relatively high energy storage and conserved energy used for advertisement calling. In the middle of the breeding season, the chorus size of male frogs was the highest, indicating a breeding peak. Individuals that emerged at this time showed signs of energy depletion and low immunity. Towards the end of the breeding season, male frogs had high energy storage and immunity, likely due to the influx of new individuals at this time. During this period, individuals displayed rapid cries for breeding spurts. Our findings imply that prolonged breeder species may adjust their breeding participation in response to the risks and benefits of breeding timing.AbstractThe calling behavior of anurans should be studied in detail as it greatly influences their physiology and immunity, particularly in prolonged breeding species. The effect can be further complicated by the emergence timing in the breeding season. We conducted a study comparing the physiology and calling behavior of the Japanese tree frog (Dryophytes japonicus), a prolonged breeder species, according to the breeding timing. During the middle of the breeding season, a high chorus size appeared, indicating a breeding peak. However, chorus size did not dominate physiology and calling behavior. In the early breeding season, frogs had a high energy storage state and immunity. In the middle of the breeding season, individuals from the early breeding season were considered to have exhausted their energy stores and had low immunity. Towards the end of the breeding season, frogs appeared to have newly introduced, at which time energy stores and immunity were as high as in the beginning. However, unlike the physiology, the pattern of calling constantly varied as the breeding season progressed. Frogs from the early season conserved energy used for calling, and frogs from the late season showed a breeding spurt for mating. Our results can help in understanding the energy metabolism of calling behavior, physiology, and disease epidemiology in prolonged breeder species. They also suggest that individuals coordinate their participation in the breeding season and that the timing of their appearance at breeding sites may not be random.