Badge size, paternity assurance behaviours and paternity losses in male house sparrows

Male quality may influence both the outcome of sperm competition and female faithfulness. In male house sparrows Passer domesticus, the size of the black throat patch (badge) signals dominance and perhaps attractiveness. So far, however, no study has reported any significant relationships between badge size, paternity and paternity assurance behaviours in this species. We found that the time mates spent together at the nest was positively correlated with badge size. Furthermore, although paternity losses were influenced by both the time spent at the nest and within-pair copulation frequency, we found no relationship between copulation rate and badge size. It seems therefore that copulation frequency served as a paternity assurance behaviour, whereas the time mates stayed together at the nest may have reflected male attractiveness. Alternatively, females may have decided to stay with large-badged males because they were better able to protect them from harassment by strange males. We also found that paternity losses were related to male badge size; average-badged males were cuckolded more often than males with smaller or larger badges. We suggest that average-badged males suffered higher paternity losses because they had different time allocation strategies than other males.