Heterophil/lymphocyte ratios predict the magnitude of humoral immune response to a novel antigen in great tits (Parus major)
Animals display remarkable individual variation in their capacity to mount immune responses against novel antigens. According to the life-history theory, this variation is caused by the costs of immune responses to the hosts. We studied one of such potential costs, depletion of somatic resources in wintering wild-caught captive passerines, the great tits (Parus major) by immune challenging the bir