Dispersal patterns of Purple Martins at the north-western edge of their range

Dispersal patterns of Purple Martins at the north-western edge of their range
Dr. Glen Hvenegaard, University of Alberta
With Purple Martin populations in decline, particularly in eastern North America, it is helpful to know more about their breeding dispersal patterns. This study examined the effects of age and sex on the dispersal frequencies, distances, and directions of martins at the north-western limit of their breeding range. We used two datasets: 1) adult martins that were originally banded in central Alberta as nestlings and recaptured during the summers of 2017 and 2018, and 2) historical band encounter records of the eastern population of martins in Canada. In Alberta, 36% of birds dispersed from natal sites, with an average distance of 24 km, most commonly to the northeast. Across Canada, 29% of birds dispersed, with an average distance of 183 km, most commonly to the east and northeast. In both datasets, juvenile and male birds were more likely to disperse than adult and female birds. The northeastern dispersal of martins could be in response to habitat or climate changes, and has important implications for landlords providing nest boxes.