Effect Of Ecological Factors On Reproductive Success Of Magpie(Pica Pica)

The reproductive success and effect of ecological factors on breeding of Magpie(Pica pica)in Xianghai National Nature Reserve,Jilin,China,were surveyed during the breeding seasons(March to August)in 2014-2016.We surveyed 97 nest sites which include 77 nests' breeding success of Magpie.The The study mainly included breeding density,characteristics of nest-site selection,the influence of magpie nest on other breeding birds and experimental parasitism study.Our results showed that the breeding time of Magpie was mainly from March to June;the clutch size was 6-8 eggs,up to 9-11 eggs;incubation period was 17-18 days while brood period was 21-25 days.The laying date was significantly related to the clutch size.Earlier breeding Magpies had larger clutch sizes.This may be explained by parents' quality and nest predation rate.The main nesting trees of Magpies were elm(Ulmus pumila)and polar(Populus alba).Nest site selection was influenced by tree height,tree diameter at breast height and distance to forest edge.The influencing factors of reproductive success were nest predation and nest usurpation,which resulted in low success to 29%.However,the predation rate was 35% which was high enough to be treated as the primary factor of breeding failure and the significantly difference of distance to the forest edge may express the nest predation tendency.A total of 46 cases of 6 species breeding birds used Magpie nests were found in study area which included 17 cases of nest usurpation.The usurped nests had higher nesting trees,larger tree height and larger tree diameter compared with non-usurped nests.Compared with previous work,the lower tree height of Magpie nest in our study may be confined to tree species composition in habitat and nest usurpation.The trade-off between food and predation may decide the distance to forest edge of Magpie nest site choice.Although cuckoos existed in the study area,no eggs or young of cuckoos were found in any Magpie nest.We experimentally studied the egg recognition of Magpies through vision and olfaction by using model eggs and the chick recognition of Magpies by feeding Daurian Jackdaw(Corvus dauuricus).The result seems to be that Magpies had no egg recognition or chick recognition.The experiments of nest guarding behaviors showed that Magpie recognize Eurasian sparrowhawk(Accipiter nisus)and Spotted-necked dove(Streptopelia chinensis),while it may recognize common cuckoo(cuculus canorus).The non-synchronization of breeding may be the main reason for no cuckoo parasitism on Magpies.