Body Morphometrics and Molt of Bonaparte's Gulls in the Quoddy Region, New Brunswick, Canada

Abstract

In the Quoddy region of New Brunswick, Canada, the postnuptial molt and feather renewal of Bonaparte's Gulls lasted about 14 weeks with the primary feather molt of the second-year birds being more advanced than that of the adults by 20 to 30 days or 2 to 3 primary feathers. Males were larger than females by body weight, and body, culmen, and tarsal lengths. There was a general trend for migrants passing through the Quoddy region during July and August to be larger in size than during October and November. Based on culmen and tarsal lengths measured on museum specimens collected from different geographical regions of the breeding range, there was a general trend for decrease in body size from east to west, which suggests that the first migrants through the Quoddy region represented populations from the east followed later by western populations.