Resource use and defence by ruby-throated hummingbirds during stopover

Abstract

Abstract Many migrants must forage en route when fuel reserves are depleted and access to resources can be influenced by a variety of factors, including the sex, age, and current fuel stores of individuals, as well as resource availability. The objective of this study is to determine the factors that influence the use and defence of resources by migrating ruby-throated hummingbirds (Archilochus colubris). Our results illustrate that resource use: (1) is dependent on sex and resource defence, (2) decreases with fuel load and (3) increases with stopover duration as well as the number of unique feeders visited. Resource defence is closely tied to (1) competition, with the greatest conspecific density resulting in focal individuals being chased from feeders and (2) the interplay between resource quality and fuel load. Our research enhances our understanding of strategies migratory birds use to acquire and defend resources during stopover.