PATERNITY AND PATERNAL CARE IN THE POLYGYNANDROUS SMITHS LONGSPUR

In species where females copulate with more than one male during a sin gle breeding attempt, males risk investing in offspring that are not t heir own. In the polygynandrous Smith's longspur (Calcarius pictus), f emales copulate sequentially with one to three males for each clutch o f eggs and most of these males later assist in feeding the young. Usin g multilocus DNA profiling, we determined that there was mixed paterni ty in >75% of broods (n=31) but that few offspring (<1% of 114 nestlin gs) were sired by males outside the polygynandrous group. Male feeding rate increased significantly with the number of young sired, with mal es siring four nestlings feeding the brood at double the frequency of males siring only a single nestling. However, male Smith's longspurs a ppear to show a graded adjustment of paternal care in response to pate rnity only when other males are available to compensate for reduced ca re: feeding rate did not vary in relation to paternity when only one m ale provisioned young at the nest. There was no evidence that males co uld recognise their own offspring within a brood and feed them prefere ntially. The number of offspring sired by each male was significantly correlated with the number of days spent copulating with the attending female: on average, a male sired one offspring for every 2 days of co pulatory access. If males use their access to females to estimate pate rnity (and thereby decide on their subsequent level of parental invest ment), a positive relationship is expected between the amount of femal e access and the subsequent feeding rate to the nestlings. Nonetheless , male feeding effort was only weakly correlated with female access an d more study is needed to determine how males estimate their paternity in a brood.