Abstract

Animal personalities are individual behavioural tendencies that are consistent across time and context. The presence of personality has yet to be assessed in reindeer (Rangifer tarandus), a species where subdominant males may attempt to gain access to females within a harem while risking physical confrontation with a dominant male. I investigated bold-shy personality in subdominant male reindeer based on individual subdominant male propensity to penetrate into a mating group and flight initiation distance. I also investigated how boldness related to somatic cost and reproductive success, respectively. Data was collected at the Kutuharju Reindeer Research Station in Kaamanen, Finland, where measures of personality were generated using field observation data based on the relative frequency of dominant male-subdominant male agonistic interactions over four years and subdominant male flight initiation distance measured over one year. Individual propensity to penetrate a mating group was not significantly repeatable and therefore not a personality trait, but instead decreased with subdominant male weight and group sex ratio, and was best described by a quadratic relationship with day of the mating season. There was no relationship between propensity and relative weight loss or reproductive success. Subject to no discernable fitness consequences related to propensity to penetrate a mating group, individuals do not adopt personalities and may instead base decisions on proximate factors. Flight initiation distance increased with starting distance and was negatively related to trial number. Individual flight initiation distance was significantly repeatable and therefore indicated personality differences along the bold-shy axis.