Age-Specific Reproductive Strategies and Delayed Embryonic Development in an Old World Fruit Bat, Ptenochirus jagori

Ptenochirus jagori (Megachiroptera, Pteropodidae) is a tropical cynopterine fruit bat restricted to the Philippine islands. Samples of bats were obtained over 4 years, and reproductive tracts were preserved and examined using standard histological techniques. Reproductive status also was recorded for bats captured, marked, and released. A facultative post-implantational delay in embryonic development was detected in young P. jagori females reproducing for the first time. The delay occurred at the stage of gastrulation and could last up to 5 months. Adult females showed little evidence of a delay in development. With this delay, young females gave birth only once in their first year and synchronized parturitions with those of adults. Adult females had a gestation period of 4 months and gave birth twice a year, once in late March and early April and once in August. Morphology of early development was similar to that of other cynopterine fruit bats. The evolution and significance of a post-implantational delay in development are discussed.