The elfin-woods warbler (Dendroica angelae), or reinita de bosque enano (Spanish name), is a bird endemic to the Caribbean island of Puerto Rico where it is a local and uncommon species. Discovered in 1968 and described in 1972, it is the most recently described species of New World warbler (family Parulidae). The species name, angelae, is a tribute to Angela Kepler, one of its discoverers. An insectivore, it feeds by gleaning small insects off leaves.
Due to its small populations and restricted habitats, conservation efforts were begun in 1982 to protect this species but, as of 2005, the warbler was still in need of protection. The species is not in immediate danger as the majority of its habitat is protected forest, but introduced species, such as rats and mongooses, habitat reduction, and natural disasters represent potential threats to the population.
The elfin-woods warbler is one of 29 species in the genus Dendroica of the family Parulidae, the New World warblers. It was first observed in 1968 by Cameron and Angela Kepler while conducting observations on two Puerto Rican endemic birds, the Puerto Rican parrot and the Puerto Rican tody. On May 18, 1971, a specimen was captured in the Caribbean National Forest, which at the time was believed to be its only habitat. A year later Kepler and Parkes described and named the species making it the most recent warbler (Dendroica spp.) discovered in the New World. Also, it is the first species described in the West Indies since 1927 and the first Puerto Rican species described in the 20th century.