Life History Survey On Horned Lark (Eremophila Alpestris) In Gannan Plateau

Belonging to genus Eremophila,family Alaudidae and order Passeriformes, Horned Lark(Eremophila alpestris)distrabutes broadly in the world and has been widely studied since late 19^thcentury.I studied the breeding ecology of the Horned Lark population living in Gahai,Gansu province,and primarily discussed the life history strategies of the populations living at high altitude.Gahai lies at about 3,500 m altitude on the easten edge of Tibetan Plateau. Horned Lark is one of resident bird species,as well as dominant species.The survey on breeding ecology of Horned Lark in Gahai was held from 21^thApril to 15^thAugust in 2006 and 11^thApril to 31^thJuly in 2007.All of 71 birds,44 males and 27 females,were caught by mist nest.The results showed that the dimorphism of adult Horned Lark is significant.There are significant difference between the male and female in the measurements of weight,bill length, wing length,total length,tail length and tarsometatarsus length.The average measurements of the diameter of nest cavity is 9.4(±1.1)×8.1(±0.8)(cm)(n=42),the inside diameter of nest is 7.3(±0.8)×6.5(±0.8)(cm) (n=41),the depth is 4.6(±0.8)cm(n=41)and the mass is 24.4(±11.2)g(n=33).Nest materials are common fibrous materials in surrounding environment.The mean clutch size of the population is 2.48(±0.50)(n=77).Mean dimension of the egg size is 23.06(±1.00)mm(n=156)at elongation and 16.35(±0.65)mm (n=156)at breadth.Fresh egg mass is 3.28(±0.28)g(n=156),about 10.35%of female mass.The incubation period is about 11 days to 12 days.Only female constructs the nest and incubates,while both parents feed the young. Young birds grow and develop fast in 9.26 days' nestling period.The measurement of tarsometatarsus length is near to that of the adult when young birds leave the nest. And body weight,bill length,wing length and tail length are shorter than those of the adult.Gahai population reproduct 2 to 3 clutches a year.Nest success rate of the total 107 nests in 2006 and 2007 is 22.43%;hatching rate is 45.85%;and reproductive success rate is 24.45%.The main cause of the failure is nest predation.Compared with other studies,the clutch size decreases with increasing altitude, while egg size increases.To adapt the hostile environment and keep from predation, the Horned Lark in Tibetan Plateau developed a breeding strategy of reproducing small clutch with large eggs.Low temperature and hypoxia made the nestling growth rate decreases with the increasing altitude.