Age and Sex Differences in Stopover Behaviours and Flight Performance in Black-throated Blue Warblers
Abstract
Differential migration by sex and age is commonly observed in passerines. Previous studies have found differences in wing morphology between sex and age classes which could affect their movement ecology. In this thesis, I examine whether migratory stopover duration and nocturnal flight speeds differed between age and sex classes in 89 Black-throated Blue Warblers (Setophaga caerulescens) using movement data obtained by Motus Wildlife Tracking System and meteorological data from the NCEP/NCAR Reanalysis II project. Second year birds (hatched during the previous breeding season) had longer stopovers but similar post-departure movements to after second year birds (hatched before the last breeding season). There were some differences in morphological characteristics between age and sex classes. Second year birds had more wing wear than ASY birds, and females had smaller wings than males. Overall, there was no evidence that morphological differences influenced flight characteristics, but flight performance was dependent on wind conditions.