Breeding consequences of flavivirus infection in the collared flycatcher

Abstract

Background: The breeding consequences of virus infections have rarely been studied in avian natural breeding populations. In this paper we investigated the links between humoral immunity following a natural flavivirus infection and reproduction in a wild bird population of collared flycatcher (Ficedula albicollis). We analyzed plasma from 744 birds for antibodies and correlated these results to a number of reproductive components.

Results: Nearly one third (27.8%) of the sampled collared flycatchers were found seropositive for flavivirus. Males had significantly more frequently flavivirus antibodies (32.3%) than females (25.1%). Seropositive females differed significantly from seronegative females in four traits: they had earlier lay date, higher body weight, higher survival rate and were older than seronegative females. The females did not differ in clutch size, number of fledged young or number of recruited young. Seropositive males had female partners with earlier lay date, i.e. the males bred earlier and they also produced more fledged young than seronegative males. In contrast, the males did not differ in clutch size, number of recruited young, male weight, age or survival. Interestingly, seropositive males had larger ornament, forehead badge size, than seronegative males.

Conclusions: Collared flycatchers with an antibody response against flavivirus were more successful than birds with no antibody response, for any of the measured life history traits. The positive link between flavivirus antibody presence and life-history trait levels suggest that it is condition dependent in the collared flycatcher.

Keywords: Flavivirus; Host ornament; Host reproduction; Humoral immune response; Trade-off; West Nile virus.

Fig. 1

Life history traits against flavivirus specific antibody measures in the collared flycatcher. Females a) and males b) divided into two flavivirus-specific antibody levels (“Seronegative” (< 30% inhibition) and “Seropositive” (≥30% inhibition) and visualized in histograms against (mean) lay date. Females were also plotted for adult weight, adult survival (proportion annual survival) and age (in years). Males were in addition plotted for number of fledged young, number of recruited young and mean forehead patch area (ornament).