Behavioral estimates of male mating success tested by DNA fingerprinting in a polygynous mammal

We used DNA fingerprinting to determine paternity of 80 calvesborn into the individually monitored population of red deer(Cervus elaphus) on the Isle of Rum, Scotland. Using the paternityinformation, we investigated the assumptions and predictionsof behavioral estimates of male mating success, on which previousstudies in this population have relied. Over an 11- day intervalin the rut centered on a female's estimated date of conception,the probability that a male fathers a calf is closely relatedto the number of days he holds the female in his harem, increasingfrom 0.12 for 1 day to 1.0 for 6 days or more. We compared threemethods for estimating the reproductive success of individualmales from field observations of harem membership with truesuccess revealed by DNA fingerprinting. All three methods accuratelyidentified the relative success of individual males but werepoor predictors of absolute success: the behavioral methodsunderestimate the true success of successful males and overestimatethe success of many males who, in fact, fail to father any calves.In consequence, variance in male mating success is greater thanprevious behavioral estimates for this population suggested.Both harem membership data and observations of mating and otherestrous behavior can be used to identify males most likely tofather a specific calf.