Study On Breeding And Reproductive Hormone Levels Of The Crested Ibis In Sichuan

As a national protected wild animal,the Crested Ibis was once considered to have been extinct in the wild.Since the discovery of 7 wild the Crested Ibises in Yangxian country,Shaanxi Province in 1981,the Crested Ibis population has further recovered and expanded.So far,the artificial and reintroduced populations of the Crested Ibis have been established in Yangxian,Tongchuan,Zhouzhi Louguantai,Ningshan County,Henan Dongzhai National Nature Reserve and Zhejiang Deqing County.Sichuan was once the only historical distribution area of the Crested Ibis in the southwestern region and extinct due to habitat destruction.At the end of 2016,under the coordination of the State Forestry Administration and other units,50 Crested Ibises from Shaanxi,Henan and Zhejiang were reintroduced to the Leshan breeding base in Sichuan.Studies have shown that reintroduction has an impact on the reproductive ecology of the Crested Ibis.It is unclear whether the reproductive ecology and reproductive hormone levels of the Crested Ibis population in Sichuan are affected.Therefore,this study intends to evaluate the reproductive status and reproductive hormones of the reintroduction of the Crested Ibis population in Sichuan.Our results will provide scientific fundament for the sustainable and healthy development of the Sichuan Crested Ibis population.In this study,the reproduction status and reproductive hormone levels(testosterone,estradiol,progesterone,follicle stimulating hormone,and luteinizing hormone metabolites)of the Sichuan Crested Ibis population were evaluated by counting the spawning and hatching rate during the breeding period in 2017-2018,and by enzyme-linked immunosorbent assay(ELISA)from the feces during the breeding period in 2018-2019.The results are as followed:(1)The number of eggs laid was 140,and the fertilization rate was 61.4%(86/140)and the brooding success rate is 90% in 2017.In 2018,the number of eggs laid was 141,the fertilization rate was 55.3%(78/144),and the success rate of brooding was 81%.The fertilization rate and the success rate of brooding in 2018 were lower than those in 2017.Comparison with the long diameter,short diameter and quality of the eggs,the egg quality in 2017 was higher than that in 2018.(2)The reproductive hormone levels in the feces were determined by ELISA.The results showed that testosterone,estradiol,progesterone,follicle stimulating hormone and luteinizing hormone in the feces were obviously changed during reproductive period.The concentration of testosterone and estradiol in female is lower during courtship period,and testosterone peaks during brooding period;estradiol is peak during mating period;progesterone concentration is lower during the courtship period,and reaches the maximum during the shelling period;FSH is low during courtship period,and the spawning period showed an upward trend;The change of LH was similar to that of FSH.Male's testosterone showed a lower pre-and post-study period and a shorter courtship period,followed by a rise and a peak change during brooding period.The change trend of estradiol showed a lower during courtship period and a rising during mating period.The change of progesterone was similar to that of testosterone,and the concentration was the highest during brooding period;FSH also peaked during brooding period;and the LH concentration showed an upward trend during spawning period.There is no significant difference in the annual variation of reproductive hormone.Our results showed that different habitat environments have impacts on reproductive physiology of the re-introduced Sichuan Crested Ibis.(3)According to the reduced fertilization,hatching and brooding success rate,and the changes of reproductive hormone during breeding period of the Crested Ibis population in Sichuan,the following measures need to be taken.(1)Expand or find suitable breeding bases or wild habitats and more attention should be paid to the quality of habitat environment;(2)I Strengthen the observation and study on the hatching and brooding behavior of the Crested Ibis,and improve the hatching and brooding success rate of the parental birds,and rationally matched through genetic lineage management;(3)Carrying out artificial insemination of the Crested Ibis to maintain the healthy and sustainable development of reintroduced population.In conclusion,ex-situ conservation has an impact on the reproductive physiology and ecology of the Sichuan Crested ibis.Our result will benefit to further reproductive studies on later ex-situ conservation of the Crested Ibis.