Two introduced crocodile species had changed reproductive characteristics in China

The purpose of this study was to study the reproductive characteristics of the Nile crocodile and Siamese crocodiles after introduction into China since the time this occurred near the end of the last century. The data for the eggs and young crocodiles (recently hatched crocodiles) of two introduced species were collected at a Sanya crocodile breeding farm in Hainan. The characteristic variables of crocodile eggs were statistically analyzed, and the results indicated that: egg mass of the Nile and Siamese crocodile was significantly correlated with the egg length and width. Regression analyses were used to develop the linear equation between the egg length, egg width and egg mass. There was a strong positive correlation between the egg mass and initial weight of young crocodiles. The linear equation for assessing egg mass and initial weight of young crocodile was developed for regression analyses. There was no significant linear relationship between clutch size and egg characteristics. Mating time of the Nile crocodile in Hainan (November-April) and the spawning season (March-May) are significantly earlier than in the Zimbabwe region of origin. The average of clutch size and the mean size of eggs for Nile crocodiles in their native habitat is greater than the introduced region as indicated by analyzing data using a two-sample t-test. The Siamese crocodile spawning time was similar in the Hainan and Zimbabwe regions, but the size of clutches and the mean size of eggs in the introduced region were greater than in their native region as indicated by results using a two-sample t-test.