震旦鸦雀种群生态的研究

STUDIES ON THE POPULATION ECOLOGY OF THE CHINESE CROWTIT

震旦鸦雀是一种小型濒危鸟类,在IUCN和ICBP出版的红皮书中,共同认定为Ⅰ(Indeterminate)级。本文是作者于1985~1986年期间,对种群生态进行研究的首次报道。该鸟栖息于上海沿海芦苇滩中。种群密度1.21±0.57对/公顷。文中还论述数量变动和种群活动的变化规律。在奉贤沿海估计有290~387对。在越冬期中,剥取芦鞘内的寄生虫等为食。由于围垦不断发展,栖息地日益缩小,因此在生存上受到严重威胁。

The Chinese crowtit(Paradoxornis hcudei heudei David)is a small rare native bird residing in China with a patchy distribution.This species is listed as indeterminate in the IUCN Red Data Book and the ICBP Bird Red Data Book.A study(1985-1986)of its population ecology was carried out at Fengxian county coastal areas as the following.1.The population density were 1.21±0.57 pair/ha and it is greatly influenced by the growth,density of the reeds and also the reed type and environmental condition of the reeds.For example in irregated reed ponds the density were only 0.56±0.33 pair/ha.In short reed beds the density were 1.67±0.58 pair/ha.In coastal areas of Fengxian the population numbers was estimate to be 290-387 and it is known to be the largest population in the wild.2.During the breeding period the activity shows significant changes,its activity frequency was from 3.33±2.23 ind/km/hr in May to 14.00±7.29 ind/km/hr in September,being four times higher in early spring.3.Before reproduction period the crowtit often were in family groups or mixed family groups,grouping activities frequency were above 91%.During the reproduction period 41.86%were found to be in pairs in May;singles were highest in June with a percentage of 60.71.4.During wintering the crowtit mainly preys on scale insect(Aclerda sp.)that hide in the leaf sheath of the reeds.Through observation,one is able to see or hear them rip open leaf sheath.The cutting down of the reeds in the winter,undoubted is the most important factor responsible for the decline of its habitat and lost of food resources.Only tiny remnants of the reeds are left for the crowtit to inhabit and proy-ided feeding grounds.Through the large scale rceds destruction for paper pulp and rapid expansion in reclaiming tideland for cultivation.Rapid and effective action is required to secure this habitat for saving this species from extinction.The author suggests establishing a nature preserve for this small endangered bird.