| The Crested Ibis (Nipponia nippon) is one of the world’s endangered species, which has been shown a great concern for its conservation and research at home and abroad. Since the Crested Ibis was rediscovered in Yangxian County in1981, the wild population has increased from7individuals to more than1,000, with another approximately1,000captive-bred birds which resided in12conservation centers and zoos in China, Japan and Korea, respectively.Reintroduction refers to the attempt to reestablish self-sustaining populations of endangered species within their historical ranges usually through the release of captive-bred individuals into the wild. It’s a creative protective measure for wilding and expanding population ranges of endangered species. In May2007, a first reintroduction project of Crested Ibis in the world was conducted in Zhaigou Village (33°23’27" N,108°20’29" E, at an altitude of1,050m) in Ningshan County of Shaanxi Province. Fifty-six captive-bred individuals were successively released to wild from2007to2011. To date, most of the reintroduced individuals survived the period of large ranged dispersal, and the population is in a self-sustaining stage now.Up to the present study, the individuals we refered include56captive-reared ibises which were released from May2007to October2011,66nestlings born in the wild and47juveniles fledging successfully during6years from2008-2013. Capture-recapture data about each individual were obtained using methods of banding, radio-telemetry and field observations. In Windows7operating system, capture-recapture data were processed and analyzed by C-J-S model specified from software Program MARK7.1, respectively on annual survival of all individuals and the released individuals, seasonal survival and survival of different age groups for the reintroduced population.Our results indicated that,(1) the model of φ(t)p(.) was optimal to annual survival of all individuals at which the estimated suvival was0.462±0.098(2008, effective sample size, ESS=12),0.762±0.093(2009, ESS=16),0.500±0.081(2010, ESS=19),0.828±0.070(2011, ESS=24),0.739±0.065(2012, ESS=34), and0.813±0.056(2013, ESS=39), respectively;(2) the model of φ(t)p(.) was optimal to annual survival of the released individuals at which the estimated survival was0.462±0.098(2008, ESS=12),0.778±0.098(2009, ESS=14),0.571±0.094(2010, ESS=16),0.875±0.083(2011, ESS=14),0.750±0.088(2012, ESS=18), and1.000(2013, ESS=18), respectively;(3) the model of φ(season)p(.) was optimal to different seasonal survival. The estimated survival (0.805±0.025, ESS=40) in breeding season is lower than that of non-breeding season (0.903±0.021, ESS=45);(4) the model of φ(a3-J.)p(.) was optimal to survival of different age groups at which the estimated survival was0.363±0.145(ESS=4) for yearlings,0.727±0.095(ESS=16) for adults, and0.769±0.117(ESS=10) for juveniles, respectively.We concluded that the factors of demographic stochasticity are mainly the extensive dispersal of the released individuals in early stage and poor ability of flight for fledgings. The factors of environmental stochasticity such as food resource, predation, habitat, human disturbance, bad weather, flight strike and electrocution of power lines, are mainly contributed to the survival for the reintroduced population. Similar to the wild populations in Yangxian County, the predation of snakes and corvids disturbance have been found to be main causes of mortality for the reintroduced population in Ningshan County. Therefore, effective protection of yearlings is crucial to survival. The results of the reintroduction in Ningshan County in China was more promising compared with the similar release project which was believed to be partially successful in Sado Islands in Japan.As mentioned above, the recommendations we suggested are as follows:(1) A "dumbbell-shaped"nature reserve along Chang’ an River should be established in order to form links between nesting and foraging sites;(2) We must focus on the post-release monitoring especially in the brooding period;(3) The nest predation such as Elaphe carinata, Accipiter gentilis was reduced to a lowest possible level by careful field monitoring;(4) We should encourage the local people to exsert their enegies on the conservation of the Crested Ibis by carrying out a series of beneficial projects. |
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