Parental Feeding Strategy Of Azure-winged Magpies Cyanopica Cyana On The Tibetan Plateau

Parental feeding strategy affects offspring survival and parents’breeding success in altricial birds. In this dissertation, we mainly focus on the Azure-winged magpies Cyanopica cyana on the Tibetan Plateau. After collecting reproductive biology data and behavioral ecology data in the field, we investigated the feeding strategy of Azure-winged magpies.Based on the field research about azure-winged magpies of the Tibetan Plateau in2011-2013the results showed that:1) Azure-winged magpies on the Tibetan Plateau have a mean clutch size of5.43(±1.08, n=229). The weight and volume of newly-laid eggs was6.23g (±0.58, n=1239) and5.90cm3(±0.57, n=1227).2) For those successfully hatched eggs, their weight at the first day of incubation increased significantly with the laying sequence, weight of female and linear structure of male.3) The body weight of nestlings at fledging and the fledgling number in cooperative groups was obviously higher than that in solitary pairs.4) The feeding efficiency (the ratio of fed nestling to the brood size) decreased not only with nestling age but also with brood size. At the same time, single nestling in one brood feeding efficiency also decreased with the nestling age.5) Though in all nests parental feeding rate increased with the nestling age, its increasing range was obviously larger in larger broods than that in smaller ones.6) Parents provide male offspring with more food.7) By comparing the core offspring in different modes of reproduction, we found that in cooperative groups there are more male nestlings, but more female nestlings in solitary pairs.Both sexes of azure-winged magpies contributed in provisioning the brood, but warming the nestlings was carried out by the female alone. The task of protecting nest is mainly carried by males. The main composition of helpers is male. The main contribution of helpers in cooperative groups is to defend territories and helpers don’t directly provide food for nestlings. The azure-winged magpies tend to having more daughters but feeding more food to son, which to make sure that son will have a stronger body and then to be a good helper. In this way they can carry their point that to acquire more daughters and stronger sons.