A total of 236 eggs were laid by the population of the wild crested ibis ( Nipponia nippon ) in 72 nests in Yang County,Shaanxi Province,China,from 1981 to 1997,with an average of 3 3 eggs per nest.Among the eggs,169 nestlings were hatched,accounting for 71 6% of the total;and 129 young birds grew up and flew from their nests,accounting for 76.3% of all the nestlings.Since 1981,133 birds have been brought up in the county.The birds have established 27 breeding sites in the county,with the number of breeding couples increasing from 2 pairs in 1981 to 10 pairs in 1997.The birds mature at 2 years old,either male or the famele is 2 years old,The maximum age difference between the 2 sides of a couple is 2 years.
