Different reproductive tactics in male collared flycatchers signalled by size of secondary sexual character

Most studies of variation in male reproductive tactics have focused on cons picuous categorical differences in mating behaviour (i.e. variation in mati ng strategies). However, in the presence of trade-offs between investment i n competition over matings, parental care and survival, a. male's optimal a llocation rule might vary according to his physiological condition and soci al or ecological environment. Thus, there may also be more subtle variation in male reproductive tactics. Here, I show that the reproductive effort (e stimated as residual change in condition) of male collared flycatchers was affected by the size of their forehead patch (a secondary sexual character) , age and date of arrival at the breeding grounds. Among early males (i.e. males with a high likelihood of both attracting more than one female and ob taining extra-pair copulations), large-patched males made a relatively larg e reproductive effort and as a result were in worse condition at the time o f feeding offspring as compared to small-patched males. Furthermore, among early breeders, young males and males with experimentally increased forehea d patch size made a relatively high effort. By contrast, regardless of age and badge size, there were no such patterns observed among late breeders. T hese results suggest that collared flycatchers use different reproductive t actics depending on both internal and external factors, and that the size o f a secondary sexual trait may not only indicate variation in individual co ndition but also predict how resources will be allocated between pre- and p ost-mating reproductive activities.