Justification of Red List Category
This species is listed as Endangered because it has a very small range within which the species is thought to be declining as a result of habitat loss and degradation.
The population has been estimated to number at least 1,800 mature individuals, based on censuses conducted using playback methods. This is roughly equivalent to at least 2,700 individuals in total. Surveys by Arendt et al. (2013) in the El Yunque National Forest found a population density of 0.02 individuals/ha in elfin woodland and 0.2 individuals/ha in palo colarado forest in 2006. This protected area is estimated to contain 368 ha of elfin woodland and 3,441 ha of palo colorado forest (USFWS 2016). Using the above population densities and habitat areas, the population in the El Yunque National Forest is estimated to number c.700 individuals. Based on habitat-specific population densities found by Gonzales (2008) and the estimated areas of each habitat within the Maricao forest (USFWS 2016), the population in the Maricao forest is estimated at c.2,000 individuals. The population is estimated as 2,700 individuals, which equates to 1,800 mature individuals.
The species is may have declined in recent years owing to habitat degradation. A study by Arendt et al. (2013) at El Yunque National Forest found a decline from 0.2 to 0.02 individuals/ha in elfin woodland and a decline from 1 to 0.2 individuals/ha in palo colarado forest between 1989 and 2006 which may equate to a decline of 10-25% over 3 generations or 10 years. There is no indication that the population in Maricao Forest and adjacent land has declined, although habitat loss in the adjacent land is ongoing. An overall, ongoing population decline is therefore assumed.
Setophaga angelae was only discovered in 1968 and is endemic to Puerto Rico (to USA) (Raffaele 1983). It was formerly considered to occur at four disjunct localities: in the east, the Sierra de Luquillo (El Yunque National Forest/Bosque Nacional del Caribe) and the Sierra de Cayey (Carite State Forest) and, in the west, the Cordillera Central (Maricao and Toro Negro Commonwealth Forests), but its existence at some of these sites has been questioned and it is now thought to be restricted to two widely separated locations: the Sierra de Luquillo and the Maricao State Forest and adjacent private lands (Anadón-Irizarry 2006, Delannoy 2006, V. Amadon in litt. 2016, USFWS 2016, Anadón-Irizarry et al. 2017). Extensive surveys between 2012-2016 were unable to detect the species's presence in the Carite Commonwealth Forest and it is considered extirpated in this region (Anadón-Irizarry et al. 2017). In optimal habitat it can be locally common, and although the population was previously thought to be no more than c.300 pairs (Curson et al. 1994), more accurate counts put the population at c.2,700 individuals.
Although it inhabits elfin or montane dwarf forest on ridges and summits, montane wet forest, and sometimes ranges to lower-elevation wet forest, it reaches its highest densities in Podocarpus dominated forest (Cruz and Delannoy 1984, Raffaele et al. 1998, Delannoy 2006). The species is considered most common between 600-900 m within the Palo Colorado forest (Anadón-Irizarry et al. 2017, Campos‐Cerqueira et al. 2017). Preferred areas have a dense canopy with vines, high subcanopy and sparse understorey (Curson et al. 1994, Raffaele et al. 1998). It shows a string preference for undisturbed forest, but has been recorded in secondary habitats and plantations (Cruz and Delannoy 1984). Breeding takes place in March-August, and the nest is built in aerial leaf-litter trapped in vegetation or vines, usually close to the trunk, or in a tree cavity (Curson et al. 1994, Raffaele et al. 1998, Rodriguez-Mojica 2004, V. Anadón-Irizarry in litt. 2016).
By the late 1940s, the natural vegetation of Puerto Rico had been reduced to c.6% of the island's land surface, but rapid regeneration of forest increased this figure to 31% in the early 1980s, a change which will probably benefit this species (Cruz and Delannoy 1984). However, Podocarpus dominated forest, which may be crucial to this species survival, makes up a tiny percentage of the total remaining forest. In the two protected forests where the majority of the population is found, habitat modification pressures from agriculture practices and the development of new infrastructure are currently very low. However, the species is still threatened with habitat destruction, fragmentation, and degradation in suitable occupied habitat within private lands adjacent to the Maricao Commonwealth Forest (MCF) (USFWS 2015) as a result of unsustainable agricultural practices including conversion of forest to sun-grown coffee plantations, vegetation clearance and infrastructure developments (R. Rodriguez in litt. 2007, USFWS 2016). Natural disasters will continue to be a threat while the species's population and range remain so small.
Conservation Actions Underway
Both known areas are protected and the species is probably secure as long as suitable habitat is maintained in these reserves (Cruz and Delannoy 1984). Surveys were undertaken from 2011-2016 to determine the presence of a potential third population in the Carite Commonwealth Forest and surrounding potential habitat, but no individuals were recorded in this region, suggesting that the species has been extirpated from the area (V. Anadón-Irizarry in litt. 2016, USFWS 2016, Anadón-Irizarry et al. 2017). In 2011, Colón-Merced (2013) developed a habitat predictability model to map the distribution of potential habitat for the species. In 2014, the USFWS, the U.S. Forest Service (USFS) and Puerto Rico Department of Natural and Environmental Resources agreed to coordinate management actions for the species (USFWS et.al 2014). Since then, the species has been listed under the Endangered Species Act, the critical habitat is soon to be designated and it is expected that a recovery team will be assembled (V. Anadón-Irizarry in litt. 2016).
Conservation Actions ProposedDesignate critical habitat and ensure the complete protection of the two sites where it persists. Protect private land where the species occurs through cooperative agreements with landowners (USFWS). Study and report on patches of occupied habitat to identify factors limiting range and population, guide land management and aid the identification of areas of degraded habitat suitable for restoration and areas of unoccupied habitat suitable for reintroduction. Research the reasons why it disappeared from parts of its former range (Anadón-Irizarry et al. 2017). Refine the island-wide habitat predictability model and establish an island-wide long-term standardised population estimate and habitat evaluation monitoring program to allow evaluation of the effects of management actions and climate change (Anadón-Irizarry et al. 2017). Research life cycle, foraging behavior and population dynamics (Anadón-Irizarry et al. 2017).
12.5 cm. A black-and-white warbler. Similar spp. Wintering Black-and-white Warbler Mniotilta varia, but distinguished by lack of broad white crown-stripe, and behaviour: D. angelae gleans from leaves and twigs whereas M. varia creeps along trunks and limbs of trees. Voice Song is a series of short, rapid notes ending with slightly lower series of double notes. Contact call similar to first part of song. Seldom gives short, metallic chip. Hints Hyperactive, accompanies mixed flocks.
Text account compilers
Wheatley, H., Everest, J.
Anadón-Irizarry, V., Colón-Merced, R., Delannoy, C., Isherwood, I., Mahood, S., Pople, R., Rodriguez, R., Sharpe, C.J. & Wege, D.
BirdLife International (2023) Species factsheet: Setophaga angelae. Downloaded from http://datazone.birdlife.org/species/factsheet/elfin-woods-warbler-setophaga-angelae on 28/05/2023. Recommended citation for factsheets for more than one species: BirdLife International (2023) IUCN Red List for birds. Downloaded from http://datazone.birdlife.org on 28/05/2023.