A small, lively wood-warbler (Parulidae), the American Redstart is unforgettable for its conspicuous pirouettes, acrobatic fly-catching sorties, and conspicuous orange-on-black plumage in adult males—yellow-on-gray in females and first-year males. The brightly colored “flash patterns,” which the redstart displays while fanning its tail and drooping its wings, appear to flush prey from vegetation but also serve in communication among individuals of various ages and sexes. The flattened bill with well-developed rictal bristles and proportionately large wing and tail area facilitate in-flight pursuit of insect prey, a behavior used more often than phylogenetically related parulids. This warbler is also vocally conspicuous, especially during the breeding season, with its series of high-pitched phrases sung in a variety of song types and patterns. The fact that the plumage of first-year males resembles that of the female has elicited considerable interest among behavioral and evolutionary biologists.
Corresponding with its broad geographic range (Figure 1), this species occupies a wide variety of open wooded habitats in summer, including secondary forests, fencerows, and deciduous woodlands. Within its overwintering range it is found in virtually any low- to mid-elevation tropical or subtropical habitat with woods or trees, including mangroves (especially black mangroves, Avicennia), primary forest, secondary forest, coffee and citrus plantations, and even isolated trees in residential urban areas.
American Redstarts are locally abundant in much of their breeding range, particularly where appropriate habitat remains. Based on Breeding Bird Survey data (1966–2013), populations have declined in particular habitats (especially in some fragmented and urbanized landscapes) and regions while increasing in others, with only a slight decline in survey-wide abundance ( Sauer et al. 2014b ).
Its broad geographic range and abundance, conspicuous foraging and communication behaviors, and accessibly low nests, coupled with concern about declining populations of migratory birds (e.g., Sherry and Holmes 1995 , Sherry and Holmes 1996a , Faaborg et al. 2010b ), have all contributed to making the American Redstart a model species for understanding the ecology and evolution of long-distance migration ( Boulet and Norris 2006 ), including habitat quality, seasonal interactions and mechanisms, carry-over effects, migratory connectivity, sexual selection, and year-round demography. These conceptual advances in redstarts have benefited from novel application of technologies like stable-isotope analysis, satellite imagery, and 3D territory overlap, as well as renewed emphasis on full annual cycle ecology and experimental hypothesis testing ( Sherry and Holmes 1995 , Marra et al. 1998 , Faaborg et al. 2010b , Wilson et al. 2011b , Tonra et al. 2013 , Cooper et al. 2014 ).