Time Budget of Polyandrous Pheasant-Tailed Jacana (Hydrophasianus chirurgus) during Breeding Seaon in Taiwan

Abstract

The mating system of the Pheasant-tailed Jacana (Hydrophasianus chirurgus) is classical polyandry. Many hypotheses have been proposed to explain the evolution of polyandry. The replacement clutches hypothesis indicates that it would benefit both sexes if females produce more clutches as replacement when clutch lost rate is high. Females should be freed from parental duty in order to accumulate more energy for producing more replacement clutches and males should carry all or most of parental responsibility. By observing daily time budget of both males and females, we tested whether the replacement clutches hypothesis applied to Pheasant-tail Jacanas in Taiwan. Our results indicated that foraging behavior was the major activity of females in breeding season. Females spent significantly more time on foraging behavior than males during both early and late breeding stages. In males, the breeding behaviors were the dominant activity. Females increased foraging time and reduced breeding time from early to late breeding stage. Males lowered their foraging time and spent more time on breeding behaviors at the late breeding stage. The results were consistent with the predictions of the replacement clutches hypothesis. The time spent on breeding behaviors (mostly incubating behavior) of male Pheasant-tailed Jacanas peaked around noon. We suggest this was due to the high air temperature of the study site during breeding season. Males had to stay in the nests to provide eggs and chicks protection from high temperature and ultraviolet ray.