Data from: Study "Rhinoceros Auklet North American Pacific Coast (GLS)"

Models of migratory behavior predict trade-offs between fitness costs and benefits with respect to migration distance. Shorter migration distances may confer a fitness benefit by facilitating earlier breeding, however this is rarely investigated. We tested this hypothesis using a large-scale geolocation (GLS) dataset from 109 rhinoceros auklets (Cerorhinca monocerata), a differentially migrating seabird, that was tagged at 12 breeding colonies along the Pacific Coast of North America, spanning southern California to the eastern Aleutian Islands, Alaska. Using GLS-based position estimates, we determined the geographic centroid of the pelagic areas occupied by birds in winter (1 January–28 February) and then calculated the distance between their wintering centroids and colony of origin. We then used GLS light-intensity and salt-water immersion (wet/dry) data to determine each individual's date of egg-laying the following spring. Rhinoceros auklets were very widely distributed across the northeastern Pacific Ocean in winter. Among all individuals, the distance between winter centroids and breeding colonies ranged from < 100 to >2500km, being greater among individuals originating from colonies at higher latitudes. As predicted, migration distance and colony latitude were positively related to lay date: after accounting for colony-level differences in phenology, individuals that migrated shorter distances tended to lay their eggs earlier, a pattern that emerged across all populations. Our study links the migration distance of rhinoceros auklets to a fitness-related outcome, underscoring the selective pressure that migration exerts on subsequent breeding activity.