Elfin-woods Warbler (Setophaga angelae) is the latest bird to be protected under the Endangered Species Act. On June 22, 2016, the U.S. Fish and Wildlife Service finalized its listing as a “threatened” species, which means that certain federal protections now apply.
Endemic to Puerto Rico, Elfin-woods Warbler is a small black and white bird found in high-elevation dwarf forest and montane wet forest, where it gleans insects in dense midstory foliage. Similar to the Black-and-white Warbler, which winters in Puerto Rico, Elfin-woods Warbler is distinguished by its broken white eye ring and black crown.
Elfin-woods Warbler is an elusive bird. It somehow avoided discovery on a small, densely populated island until 1969 and was not described until 1973. Although its historic range is thought to be broader, it is now found in only two locations, El Yunque National Forest in the northeast and Maricao Commonwealth Forest in the southwest.
The primary threats to the warbler are the same as those facing many ESA-listed birds: habitat loss, degradation, and fragmentation due to development. In particular, its habitat has been lost to sun-grown coffee plantations, communications infrastructure, recreational facilities, and residential building.
Most of its current range is protected public land, but development has severely curtailed suitable habitat surrounding those lands. Because of the warbler’s limited distribution and small population, the species is also at risk from the hurricanes that regularly but infrequently hit Puerto Rico.
Elfin-woods Warbler had been on and off the ESA candidate-species list (meaning it was eligible for listing but precluded by higher-priority species) for almost 35 years, since 1982. Before listing, it languished on the candidate list continuously since 1999 without a final decision. FWS was obligated to make a decision on Elfin-woods Warbler in 2016 pursuant to a 2011 settlement that resolved a lawsuit involving delays in listings for candidate species.
FWS also finalized special regulations for Elfin-woods Warbler, including allowing conversion of some lands from sun-grown coffee (which does not support the warbler) to shade-grown coffee (which supports some but at reduced densities than its preferred habitat). Establishment of riparian buffer zones with native plants, which serve as “biological corridors” between suitable habitats, is also permitted.
Birdlife International estimates that the population of Elfin-woods Warblers is approximately 2,700 birds.
Other ESA-listed birds that occur primarily in Puerto Rico include the endemic Puerto Rican Parrot, Yellow-shouldered Blackbird, and Puerto Rican Nightjar, as well as the Puerto Rican subspecies of Sharp-shinned Hawk, Broad-winged Hawk, and Plain Pigeon. — Jason A. Crotty
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