Priorities for Future Research

As we still lack data on the home ranges of American Goldfinches, priority should be placed on tracking birds (e.g. with telemetry or stable isotopes), particularly at central latitudes within their range, with the aim of understanding resident versus migratory habits of certain populations. Despite a long-standing interest in the late-summer-breeding phenology of this species, surprisingly few empirical (correlational or experimental) data have been collected on the control, function, and evolution of this behavior. An understanding of geographic and individual variation in diet (i.e. seed availability and choice) could enrich our understanding of breeding habits, seasonal movements, and of their well-studied elaborate coloration.  Limited, descriptive data on calls and song could be updated in a functional context. Revisiting their facultative sequential polyandrous breeding behavior, at different locales and using molecular-genetic tools for determining paternity, could shed further light on the plasticity of avian mating systems.