If one were to walk through the Guánica Dry Forest of southwestern Puerto Rico at any time of the day, one almost certainly would hear the loud trilling outburst of an Adelaide’s Warbler (Dendroica adelaidae). The local name for this species, reinita mariposera, means “butterfly-eating warbler” or "butterfly-hunting warbler", presumably due to their appetite for caterpillars (reinita, or “little queen”, is the general term for warblers). At times, they appear to be perpetually in motion, actively searching twigs and leaves for arthropods, or squabbling with their neighbors. They are not shy of humans, and their striking colors and frequently repeated sweet song make them relatively easy to locate.
Adelaide’s Warblers are particularly common in the dry forests of southern Puerto Rico and Vieques, but are also found in wet limestone forests and secondary forests on the northern coast of Puerto Rico. However, they are absent from higher elevations and the eastern end of the island. Otherwise, they seem to be generalists both in terms of habitats used, and in the types of vegetation used within a habitat type. Their populations appear to be stable over the long term, although strong fluctuations can be seen over shorter periods of time. Although some aspects of their biology (e.g. vocalizations) have been well studied, many aspects of their behavior and ecology are not yet well known.