Study On The Factors Of Reproductive Investment And Nest Defence Investment In The Varied Tit(Sittiparus Varius)

Sexual differences always occur in parental investment and behavior during the breeding season in socially monogamous birds.Here,I used real-time video monitoring to examine the characteristics of parental investments and strategies in varied tits Sittiparus varius.And I tested the nest defence of varied tits in the nesting,incubation and brooding period.The results showed that(1)there was no significant difference between the feeding rate of the male and female parent in the early period,while the feeding rate of the female was higher than that of the male in the late period;with increasing age of the nestlings,the female increased its feeding frequency,while the male did not;the total feeding rate of the female was higher than that of the male in the brooding period.(2)The feeding rate of the female parent was positively related with its beak size,while no correlation was found between feeding rate and the male's physical characteristics;the feeding rate of the both of parents was not correlated with extra-pair paternity.(3)There was no significant difference between the nest defence of the male and female parent in the brooding period,while the nest defence of the male was fiercer than that of the female in the nesting period;the nest defence of male in three periods showed no significant difference,and the nest defence of female in the nesting and brooding period also showed no significant difference.(4)The nest defence of the parents was not related with parent's physical characteristics and extra-pair paternity.(5)The nest defence of the male was positively related with the breeding success rate while the female's nest defence was not;the nest defence was not positively correlated with the feeding rate in varied tits.Overall,in varied tits,the feeding rate of the female is adjusted according to the demand of the nestlings and is related to individual characteristics.This may be associated with the hypothesis of good parents.The feeding rate of the male did not change during the breeding season.In terms of the nest defense,the nest defence of the male was fiercer than the female in the nesting period while was the same withthe female in the brooding period.The male's nest defence is important to the breeding success in varied tits.The nest defence of parents was not related to parental body condition and extra-pair paternity.