Research On Protandry Of Four Passerine Birds In Spring At Maoer Mountain In Heilongjiang Province

Protandry refers to the phenomenon that males prepare or enter the reproductive state earlier than females in reproductive organisms.Protandry is a common phenomenon in bird migration.At present,there are seven hypotheses explaining the causes of male early emergence,which can be divided into two categories:indirect selection hypothesis and direct selection hypothesis.The indirect selection hypothesis is widely used to explain the early male appearance in migratory birds.In this paper,four species of birds were studied migrating in spring in Maoer mountain area,which in Shangzhi City,Heilongjiang Province.They were Red-flanked Bluetail(Tarsiger cyanurus),Yellow-throated Bunting(Emberiza elegans),Black-faced Bunting(Emberiza spodocephala)and Rustic Bunting(Emberiza rustica).Red-flanked Bluetail and Rustic Bunting were traveling birds,Yellow-throated Bunting and Black-faced Bunting were summer migratory birds.The data were derived from the ring data of Maoershan Bird Ring Station from 1997 to 2018,including number,date,sex,wing length and weight.The date of two sexes of different birds were analysed,and the differences of two genders migration feature dates of the same species of birds were compared;the ratio of the number of males and females was calculated and the change characteristics of the ratio with migration time were analyzed;the physical characteristics of male and female individuals,including body weight,wing length and energy state index,were calculated and compared;and the correlation between the two climatic factors of temperature and precipitation in migration period with bird migration feature time and migration time were analyzed and discussed.In the statistical comparison of spring migration feature time,the date of male was generally earlier than that of female(P=0.001).On the date of the early migration,the male is more volatile than the female.In the process of migration,a higher proportion of males was taken as the starting point,and the proportion of males gradually decreased as the main trend.In the later period of migration,a higher proportion of females was taken as the main feature.The indexes of body weight and wing length of males of the four bird species studied were generally larger than those of females of the same species(P<0.001).The average of individual physical fitness of the birds generally decrease with the advance of migration time.Temperature was negatively correlated with the date of bird migration,while precipitation is positively correlated with the date of bird migration.Meteorological factors have a greater influence on summer migratory birds than migratory birds.The results support the sensitivity difference hypothesis and constrain migration hypothesis in explaining protandry in birds.