Factors affecting post-release survival and dispersal of reintroduced Crested Ibis(Nipponia nippon)in Tongchuan City,China

摘要

Reintroduction has become a common conservation management tool to restore endangered species in their historical range.However,many attempts have failed to establish self-sustaining populations in the wild.The success of reintroductions could be improved by varying release strategies.Therefore,it is vital to determine the factors influencing reintroduction outcomes.To better understand the post-release settlement and to optimize the release strategy of the Crested Ibis(Nipponia nippon),we quantified the effects of age,sex,acclimation duration,and the timing of release events on post-release survival and dispersal distance for the released Crested Ibis in Tongchuan City,Shaanxi Province,using a generalized linear mixed effect modeling approach.Our results indicate that 40–56.3%of the released individuals survived the first year following release.Mortality was attributable to flight collisions,starvation,disease,and unknown reasons.The post-release survival probability of ibises showed a negative association with age(estimate=-0.186;95%CI:-0.350 to-0.022;P=0.026),and post-release dispersal distance was affected by the timing of release event(estimate=0.718;95%CI:0.025 to1.253;P=0.042).However,sex and acclimation period duration did not cause detectable differences in postrelease survival probability and dispersal distance.Based on our results,optimal release strategies for establishing a reintroduced population of the Crested Ibis include:(1)release of sub-adults biased and sex ratio balanced initial groups;(2)release during the non-breeding season;and(3)food supplementation immediately after release.