大山雀雏鸟的生长、食量及对马尾松毛虫种群密度的功能反应和数量反应

GROWTH AND FEEDING AMOUNTS IN THE NESTLING PERIOD, FUNCTIONAL AND NUMERICAL RESPONSE OF GREAT TIT TO CHANGES IN MASSON PINE MOTH DENSITIES

连续四年调查了浙北龙山林场大山雀的生育力及第一批雏鸟阶段食物中松毛虫食块的比率。根据雏鸟形态发育并结合外侧尾羽量度,利用关系式Y=2.42X-14(X≥6日龄,r=0.99)准确判断雏鸟日龄。对10窝424只次雏鸟连续30d扎颈取食分析,估计每只雏鸟日平均消费13.8个食块,重量为209mg(X_D=65.7),且从2—3日龄至离巢前,食物中都有松毛虫,平均为食块总数的24.9％(X_D=14.8)。随着龙山林场松毛虫种群密度的周期变化,大山雀的窝卵数、窝雏数、生殖季节开始时间及雏鸟食物中松毛虫的此率也发生变化。初步分析表明大山雀对松毛虫种群密度变化有明显的功能反应,但由繁殖而引起的数量反应不明显。

Nestling growth, feeding amounts and percent occurrence of masson pine moth (Dendrolimus punctatus) in the nestling diet of great tit (Pa-rus major) during the first nestling periods for 4 years were investigated at Long Shan Farm, northern part of Zhejiang province where the densities of masson pine moth changed regularly from 1967-1988.Growth characteristics considered mainly were body weight, standard wing length and the length of outermost tail feathers. The best correlation between the length of outermost tail feathers and the age of days from hatching (7 = 2.42 X- 14 ,X≥6 days, r=0.99) was used to determined the average age of a brood accurately. On that basis, the average fresh weight of nestling diet in different age of days were estimated (X=209mg XD = 65.7) by the crop content analysis for 30 days. Masson pine moth can be found in the nestling diet from 2-3 days to the day before fledging.The changes of clutch size, brood size, laying start and the percent occurrence of masson pine moth in the nestling diet of great tits during the first nestling periods from 1985-1988 were compared. Our data suggested that there are observable functional response of great tits to changes in moth densities but the numerical response caused by breeding are not obvious.