A Preliminary Study On The Individual Fitness Of Re-introduced Populations In Nipponia Nippon, Shaanxi Province

A series of great protection efforts for nearly four decades had brought the number of Crested Ibis population back to a sustainable level.The protective goals we have achieved are summarized as follows.First,the number of wild population increased from 7 to approximately 1,100 individuals where their range gradually expand to Daba Mountains,the east part and even the north slope of the Qinling Moutains.Second,the number of captive population increased continuously,there were more than 1,000 captive-bred individuals raised in 16 breeding centres and zoos of China,Japan and Korea.Enough captive-bred individuals make it possible to reintroduce the species to the wild.By 2014,six reintroduction programs including Ningshan(2007-05-31),Tongchuan(2013-07-04),Qianyang(2014-09-17)in Shaanxi Province,Dabie Moun tains,Henan Province(2013-04-17),Deqing County,Zhejiang Province(2014-11-12),and Sado Island,Japan(2008-09-25),were successively conducted.Particularly,the first successful reintroduction of captive-reared Crested Ibis presents a meaningful model for reintroduction programs of other endangered species.In the present study,individual fitness parameters(reproductive rates and survival rates)of the focused population were estimated.The proportion of breeding adult females,female productivity(the number of young fledged)were recorded through observing marked birds during a 9-year period.The following fate of juveniles produced last year were also investigated.The main conclusions of the present study are listed as follows.(i)A total of 30 nests were recorded from 2008 to 2016.The average nesting success rate was 70.5%±0.370(n=30).Of 214 eggs produced from 30 clutches,154 nestlings were hatched successfully in 9 breeding seasons.The average hatching rate was 71.9%± 0.883(n=30).In total,112 nestlings successfully fledged and fledging success rate was72.7%±0.465(n=30).Moreover,we calculated per female breeding probability which was to 58.6%±0.762(n=30),and there was no significant difference in female reproduction rate among 9 years(Fisher's exact test,P=0.95).(ii)Per female productivity of the reintroduced Crested Ibis was 1.88±1.30(n=30)where there were no significant differences among years(Fisher's exact test,P=0.35).However,it increased with clutch size,indicating a significant relationship between the two parameters(Pearson,r= 0.881,P=0.02).Besides,number of breeding pairs was also extremely significant correlation with female productivity(Pearson,r=0.812,P=0.008).Hence we conclude that female productivity,clutch size and number of breeding pairs are closely related.(?)The annual survival rate for adults with best model ?(t)p(.)averaged at 0.805(with 95%CI:0.556-0.837,n=51)which was similar to that of the wild population.The estimated survival(0.478,95%CI:0.548-0.771,n=22)for yearlings was relatively low.(?)While estimated survival rate,we estimated the observed population size for reintroduced crested ibis between 2008 and 2016 in the software Program MARK of 7.1.There was a significant difference in the theoretical observations of population size among 9 years(Fisher's exact test,P = 0.02).(?)Comparing with other three reintroduced population(Tongchuan,Qianyang and Henan population),the average clutch size(3.24±0.84,=66)was the highest in our focused population.The average hatching rate(71.9%),fledging rate(72.7%)and breeding success(52.8%)of the Ningshan population were higher than that of Qianyang population(55.6%,40.0%and 22.2%),but lower than that of Tongchuan population(80.0%,100%and 80.0%)and Henan population(97.8%,88.2%and 87.5%).(?)There was a significant linear correlation between female breeding probability and population size(Pearson,r=0.319,P=0.03).The number of fledglings per adult female was significantly correlated with the population size(Pearson,r=0.814,P=0.008),as well as the adult and yearling survival rate(Pearson,r=0.905,P=0.001;Pearson,r=0.695,P=0.038).As a result,with the increase of female breeding probability,female productivity,and survival rates of adults and yearlings,the population size increased accordingly.(?)The significant relationships between individual fitness(female breeding probability,female productivity,survival rates)and population size concluded that Allee effects there may be occur in Ningshan reintroduced population.