An Isotopic Exploration of the Potential of Avian Tissues to Track Changes in Terrestrial and Marine Ecosystems

Abstract

Birds are among the most successful of all vertebrates and currently occupy all of the earth's major ecosystems. Birds have evolved to exploit an impressive array of niches within habitats of both terrestrial and marine biomes where they range from extreme dietary specialists to generalists. This broad trophic diversity includes frugivory and nectarivory to piscivory and carnivory. Birds are also among the most volant of all life forms and several species migrate annually between breeding and wintering sites that may be many thousands of kilometers apart. Birds are also conspicuous, accessible, and amenable to scientific investigation, and there is a good deal of interest in using birds as indicators of ecological change at various spatial and temporal scales. They also produce a range of tissues that are amenable to dietary reconstruction using stable isotopes and so there is a growing interest in using isotopic measurements of birds to monitor larger-scale ecological processes that are associated with characteristic isotopic abundance. This chapter reviews how the isotopic measurement of avian tissues can be used to monitor ecological change. Here, ecological change is considered to be both changes in baseline food web isotopic composition and ecological changes involving the birds themselves (i.e., using stable isotopes to investigate how birds respond to environmental change).