Abstract:[Objectives] Since 2007, five released populations of Crested Ibis (Nipponia nippon) have been established in Ningshan, Tongchuan and Qianyang in Shaanxi Province, as well as Dongzhai in Henan Province and Deqing in Zhejiang Province. The reproductive behavior is important to the life history strategies, and the study on the reproductive ecology of the reintroduced Crested Ibis in Deqing can also reflect the nutritional status and local habitat quality of Crested Ibis as well as their adaptation to southern China. This paper can provide scientific support for the establishment of Crested Ibis population in southern China. [Methods] The reproductive behavior of released Crested Ibis in Deqing, Zhejiang Province, was recorded by video cameras for a total of 134 d and valid data for 2 958 h during the incubation and brooding stages in April-May 2018 and March-May 2020 in Deqing Xiazhu Lake National Wetland Park.The linear mixed models were used to explore the influence factors of the frequency of supplying nest-material and the reproductive behavior of Crested Ibis. We used Spearman correlation analysis to examine the relationship between the egg-turning frequency and the incubation process. The logistic regression model was used to explore the change of fledgling-warming duration of parent birds with the day age of fledglings. The one-way ANOVA was used to analyze the differences about nest-changing frequency between Deqing population and wild population as well as the other reintroduced populations. [Results] The results showed that the mean clutch size of the reintroduced Crested Ibis in Deqing was 3.7 ± 0.3. The hatching success rate was 90.9% and the fledgling success rate was 100.0% (Table 1). Different breeding periods, nesting conditions and the gender of parent birds significantly affected the frequency of supplying nest-material of Crested Ibis (Table 2, 3). The egg-turning frequency decreased significantly with the incubation process (Table 4, 5). The largest decline of the duration of chick-warming was at 11 days of age (Fig.1). Different brooding periods had a significant impact on the duration of fledgling-warming and the frequency of feeding and nest-changing in the Crested Ibis (Table 6, 7). [Conclusion] The higher environment temperature may be one of the reasons why the population of Deqing Crested Ibis lied eggs earlier than wild population in Yangxian County. The higher average clutch size and fledgling success rate may indicate that the Crested Ibis was adapted to the habitat of southern China. The Crested Ibis which used artificial nest-baskets spent more time supplying nest-material, indicating the necessity to improve the artificial nest-basket design in the future. We suggest to increase the open angle and reduce the depth of the nest-basket, and expand the outer diameter that close to the natural nests. At the same time, the bottom of the nest-basket should be designed as a porous and breathable structure that is conducive to drainage, in order to adapt to the humid and rainy climate in the middle and lower reaches of the Yangtze River in China.