Inconsistent reproductive cycles and postnatal growth between captive and wild Chinese pangolins and its conservation implications

Captive breeding and reintroduction are crucial to the conservation of endangered species and restoring their populations in the wild. Previous research has primarily focused on behavioral changes and adaptations in captive-bred animals prior to release; few studies have examined changes in reproductive traits and postnatal development in captivity. The Chinese pangolin, Manis pentadactyla, is Critically Endangered because its population has substantially declined in the wild due to poaching for sale in the traditional medicine and luxury food markets. Nevertheless, success in captive breeding in Taiwan may provide a pathway to the recovery of wild populations. This study combined records on captive individuals and field observations on wild Chinese pangolins over a period from 1997 to 2023 to determine (i) mating season, (ii) birth timing, (iii) body mass and total length of newborns, and (iv) postnatal growth patterns prior to weaning. The present study suggests that mating and birth timings for captive Chinese pangolins are not seasonal, as they are in the wild. Captive-born infants are significantly longer and heavier at birth than wild-born infants. Remarkably, captive-born pangolins also experience more rapid weight gain, nearly doubling in size compared with their wild counterparts by 25 weeks of age, even before they are weaned. This rapid growth is likely attributable to the high nutritional content of captive diets. This study suggests artificial feed formulas should be aligned more closely with wild pangolins' diets to reduce the risk of obesity. Additionally, reproductive parameters and postnatal growth rates in Chinese pangolins cannot be based on observations of captive individuals alone; wild populations must also be considered. We conclude that Chinese pangolins exhibit physiological flexibility in reproduction and growth in response to environmental changes, providing insights for captive pangolin management and reintroduction programs.