Puerto Rico's Elfin-Woods Warbler

Endemic to Puerto Rico, the Elfin-Woods Warbler (Setophaga angelae) is one of the most recently identified species of the Parulidae family, or New World warblers. The little black, grey and white bird was first discovered in 1968 and accepted as a species in 1972, with its name being a reference to New Zealand-born naturalist and Cornell University graduate, Angela Kay Kepler, credited with being one of the Elfin Woods Warbler's discoverers. The bird was first observed in 1968 in El Yunque forest, at the time thought to be its only habitat, when Cameron and Angela Kepler were conducting research on two of Puerto Rico's other endemic birds – the Puerto Rican Tody and the Puerto Rican Amazon. In May 1971 a bird was captured and the following year was described and named by Cameron Kepler and Kenneth Parkes.

The reason for the bird going unidentified as a separate species for so long is thought to be due to the fact that it is often mistaken for the Black-and-white Warbler (Mniotilta varia), a migratory species which visits Puerto Rico between September and early May. The most easily distinguished difference between the two species is the incomplete white eyering of the Elfin-woods Warbler as opposed to the white band across the eye, along with a white lower half of the eyering, of the Black-and-white warbler.

Initially it was thought that the Elfin-woods Warbler was restricted to the elfin forests of the El Yunque National Forest, but it was later discovered that the Carite State Forest, Maricao State Forest and Toro Negro State Forest were all favored by the little bird. However, Hurricane Hugo (September 1989) affected the populations in Toro Negro, El Yunque and Carite, and when a survey was conducted two years later it became apparent that the birds were no longer resident in Toro Negro and Carite.

Elfin-woods Warblers forage for insects in the forest canopy, and with its entire chosen habitat being protected forest it has some protection from the habitat destruction that is a problem for many bird species worldwide. Nevertheless, introduced species such as mongooses and rats, as well as predatory birds such as the Puerto Rican Sharp-shinned Hawk (Accipiter striatus venator) and Pearly-eyed Thrasher (Margarops fuscatus), pose a threat to the Elfin-woods Warbler population and it is still considered to be ‘vulnerable’ by the IUCN, with an additional reason for this status being that its very small range of habitat and low population may have significant implications for its long-term survival.

If you are birding in Puerto Rico, be sure to look out for the Elfin-Woods Warbler – one of the Enchanted Island's precious and vulnerable endemic bird species.