Predation risk and breeding site value determine male behavior and indirectly affect survivorship of their offspring

Abstract

Predation is one of the main drivers of behavioral adaptation in prey. In species with parental care, predation can affect survival of both adults and the offspring under their care. This effect can be further modulated by or combined with other factors that contribute to mating and reproductive success of adults, such as the quality of their breeding site. Using the nest guarding behavior of a treefrog with paternal egg attendance, Kurixalus eiffingeri, we quantify the effects of predation on the behavior of adult frogs and the survival of their offspring. We observed predator avoidance behavior of male frogs guarding empty breeding sites or breeding sites with eggs in response to the introduction of a predatory snake, Dinodon rufozonatum. We hypothesized that male nest guarding behavior would be negatively correlated with predation risk and positively correlated with their clutch sizes. Furthermore, we predicted that predator avoidance in male frog would negatively impact the survivorship of their offspring. We found that breeding site fidelity in male frogs was determined by perceived predation risk and breeding site value, with more males abandoning sites when exposed to high mortality risks (presence of a snake) and when the reproductive benefits (number of offspring) were low. In addition, we found that the willingness of males to return to their breeding sites was positively correlated with their clutch sizes. Abandoning breeding sites, however, can be costly to males, because abandoned eggs had a lower hatching rate. Our findings provide empirical evidence of how the costs and benefits of predation risk and breeding site value can determine the behavior of an amphibian with parental care. When faced with predation risks, the willingness of individuals to maintain their ownership over nest sites can have significant effects on their reproductive success. For species with parental care, nest defense can also be critical for offspring survival. Using an East Asian treefrog with male egg attendance, we hypothesized that males would maximize their reproductive output by increasing investment for nest sites with low predation risks and with more offspring. We found that males are more likely to invest in nest attendance when risks are low and benefits of offspring survival are high. Moreover, we found that the willingness of males to continue parental investment resulted in an increase in survivorship of their offspring. Our results show that perceived risks and benefits to the adults are important factors in determining offspring survival in an amphibian species with parental care.