The Elfin-woods warbler (Eng.) or Reinita de Bosque Enano (Sp.) (Dendroica angelae), is a species endemic to Puerto Rico. It was discovered in 1971 by Angela and Cameron Kepler from the elfin, or dwarf, forest in the Caribbean National Forest in the Luquillo Mountains. Kepler and Parkes (1972) described it as a valid taxon.
This bird is about 12.5 centimeters (4.9 inches) in length and entirely black and white. Adults have a thin, white eyebrow stripe, white patches on ear-covers and neck, incomplete eye ring, and a black crown. Immature birds are similar to the adults; however, black is replaced by grayish-green on the back, and yellowish-green on the head and underparts (Raffaele et al, 1998). Click here to hear the Elfin-woods warbler call, courtesy of USDA Forest Service.
The Elfin-woods warbler has been reported from humid montane forest habitats. The elfin forest is characterized by high rainfall, high humidity, low insolation, low temperatures, and constant winds. It is found on the summits of the mountains and is composed of dense stands of short, small diameter, twisted trees and shrubs. The Elfin-woods warbler builds a compact cup nest, usually close to the trunk and well hidden among the epiphytes of a small tree. The breeding season extends from March to June (Raffaele 1998). This species has been documented in the Toro Negro, Carite, and Maricao Commonwealth Forests, and the Caribbean National Forest. (Click on map for a larger image)
Although the Elfin-woods warbler has been documented in four locations, recent surveys in 2003 and 2004 detected its presence in only two locations, the Maricao Commonwealth Forest and the Caribbean National Forest (Anadón-Irizarry 2006). Areas adjacent to the Maricao Forest, described as suitable habitat for the species and previously planted in shade coffee, have now been converted to sun coffee, decreasing the available habitat for this species. Expansion of public facilities and the construction and maintenance of telecommunication towers also pose threats to the habitat of this species. Expansion of trail or road systems within the forests may increase pedestrian use of the area and further disturb this warbler.
The presence of recreational and communication facilities has led to an increase in feral animals, such as cats and dogs. These and other introduced species, such as rats, are potential nest predators of the Elfin-woods warbler. The Puerto Rican boa and green anole are also found within the same habitat. Although there are no records of predation by these species, that are known to prey on other birds and their nests.
Catastrophic events, such as hurricanes, may also affect the abundance and distribution of the Elfin-woods warbler. Following Hurricane Hugo in 1989, Arroyo-Vázquez (1991) did not find any individuals in the Toro Negro Commonwealth Forest. Human-induced and natural forest fires commonly occur in the Maricao Forest, particularly in the dry season. Although reported fires have mostly occurred on the lower slopes, if not contained, these fires could directly or indirectly affect populations of Elfin-woods warbler.
The Caribbean National Forest Act of 2005 designated 10,000 acres within the Caribbean National Forest as a Wilderness Area to protect the Elfin-woods warbler and the federally listed Puerto Rican parrot. The Caribbean Ecological Services Field Office has an active Partners for Fish and Wildlife program aimed at restoration of sun coffee to shade coffee plantations. Several landowners have entered the program, implementing reforestation practices at sun coffee plantations increasing the amount of suitable habitat for the Elfin-woods warbler.