三种鹭异步孵化与雏鸟生长的比较研究

根据1996～1999年的野外工作和实验饲养,研究了池鹭、白鹭、夜鹭3种鹭的繁殖、雏鸟生长和异步孵化对雏鸟生长的影响.3种鹭于4月上、中旬迁到常山、余杭鹭保护区,9月下旬陆续迁离.孵卵期池鹭为23.0 d(n=26),白鹭23.9 d(n=32),夜鹭25.3 d(n=34);孵化率池鹭为76.32%,自鹭86.96%,夜鹭95.45%,池鹭繁殖力为3.21只,白鹭3.38只,夜鹭3.50只.雏鸟体重增长与成体体形大小呈负相关.幼雏体重增长与孵化顺序相关.在生长早期(≤8 d)全部雏鸟正常发育,之后差异显著.第1和第2孵化雏鸟生长曲线相似,但明显高于第4雏鸟,表明较早孵化者获得食物能力较强,而迟孵出雏鸟有食物不足现象.该3种鹭孵育幼雏能力的最适度估计为3只左右.

A comparative study on asynchronous hatching and nestling growth of three heron species

The study on the asynchronous hatching and nestling growth of three heron species (Ardeola bacchus, Egretta garzetta, Nycticorax nycticorax) in laboratory and field at the Changshan and Yuhang heron reserve in Zhejiang Province in 1996-1999 showed that the herons migrated to the reserve in the first and second ten days of April, and left in late September. The average hatching period was 23.0 days for Ardeola bacchus, 23.9 days for Egretta garzetta, and 25.3 days for Nycticorax nycticorax. Nycticorax nycticorax had the highest hatching rate (95.45%), followed by Egretta garzetta (86.98%) and Ardeola bacchus (76.23%). The hatch ability of Nycticorax nycticorax (3.50) was higher than those of Egretta garzetta (3.38) and Ardeola bacchus (3.21). The increase of nestling weight was negatively related to the adult body size, but positively related to the hatching order. All nestlings developed well at their early growth stage, and then, there existed a significant difference among the nestlings based on the hatching order. The growth curves of the first three nestlings were similar and obviously better than that of the fourth, which indicated that early-hatched nestlings could obtain enough food, while the last one might be short of food. The optimal hatching quantity of the three heron species was assumed to be three offsprings.