Order
Passeriformes
Family
Mimidae
Genus
Margarops
 
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Version 1.0

This is a historic version of this account.  Current version

SPECIES

Pearly-eyed Thrasher Margarops fuscatus

Wayne J. Arendt
Version: 1.0 — Published November 17, 2017

Distribution

Distribution in the Americas

Pearly-eyed Thrasher has been recorded on some 100 islands in the Greater Caribbean Basin over a north-south geographical range of almost 3,000 km. Contemporary breeding has been documented on at least 81 islands and cays, with historical breeding records from several others, from: the southern Bahamas (Acklins, Crooked, Great and Little Inagua, Mayagüana, Rum Cay and San Salvador, with at least dispersal to Great Abaco, Harbour Island, Eleuthera, Cat Island, Great and Exuma, and Long Island); the Turks and Caicos Islands; Puerto Rico and small islets and cays in the Greater Antilles (but absent from Cuba, extirpated from Jamaica, and resident only on Beata Island [allied to the Dominican Republic—Hispaniola]); Antigua and Barbuda in the northern Lesser Antilles, Montserrat and Guadeloupe south to Martinique (formerly St. Vincent and Barbados), south to St. Lucia, Bonaire, and formerly La Horquilla, Los Hermanos Islands allied with Venezuela (Arendt 2006a: Chapter 4, pages 63–105; and Arendt 2006b: Appendix 1, pages 358–378; Appendix 2, Table 1, pages 379–382; and Appendix 3, Table 1, pages 385–395).

Pearly-eyes generally do not colonize islands less than about 1 km2 or islands with three or fewer resident landbird species. Nor does it inhabit large islands greater than 1,000 km2 unless they are species-poor and contain extensive, disturbed habitats. Although Pearly-eyed Thrasher is resident on small islands with as few as four landbird species, it is found most often on islands and within habitats with about 16 resident species (Arendt 2006a: Chapter 4, page 95).

Migration and Movements — Migration has not been reported in this species but several types of movements, including reproductive dispersal, extensive intra- and inter-island natal dispersal (see “Fledgling stage” under Breeding), homing in breeding males, and seasonal movements by males (see Territoriality) have been documented.

In brief, breeding adults, especially females, undergo short-distance movements to secure new nest sites after suffering reproductive loss; and fledglings disperse over distances ranging from a few hundred meters to at least 150 km from their hatch sites, even undergoing pelagic natal dispersal (Barbuda to Guadeloupe).

Homing Experiments -- Male nesters banded using unique color-codes plastic bands and US Fish and Wildlife Service numbered, alloy bands returned to their breeding territories from distances ranging from: (a) 3–9 km within the Luquillo Experimental Forest, Puerto Rico; (b) 12 km (released on Luquillo Beach, PR), all within about 10 h; and (c) 30 km after being released by Oscar Díaz on the satellite island of Viequez (<9 d) (Arendt 2006b: Chapter 6, pages 145–175).

Distribution outside the Americas

Pearly-eyed Thrasher is endemic to the Greater Caribbean Basin.

Habitat

Although sometimes considered an invasive species, Pearly-eyed Thrasher currently is thought to be native throughout its range, having arrived on islands through natural dispersal mechanisms, e.g., flight. However, dispersal via marine vessels cannot be ruled out.

The pearly-eye is a food, foraging and habitat generalist found in diverse habitats from seashore to mountain pinnacle, and has radiated naturally throughout the Greater Caribbean Basin. It is at 'home' in natural habitats and the full gamut of anthropogenic environments, including farms, resorts, and city centers where it takes advantage of crops, fruit trees, and the animals associated with them. Thrashers also take advantage of man-made structures for nesting and shelter (Arendt 2006b: Appendix 1, page 372, species 154, Vázquez 2008, Suarez-Rubio and Thomlinson 2009).

Because the pearly-eye is a prime example of an avian supertramp, excluding density-compensation islands, e.g., Mona (allied with Puerto Rico) (see Terborgh and Faaborg 1973, Faaborg 1980, Hernández-Prieto 1993) and thrasher populations sampled during periods of ecological stress (e.g., droughts and hurricanes), the pearly-eye reaches its highest numbers in wet-forest habitats because wet forests are generally more depauperate in bird species than dry forests of the West Indian islands (Kepler and Kepler 1970, Arendt 2006a: Chapter 4, pages 73–91).

Historical changes

Written accounts document that Pearly-eyed Thrasher has experienced severe population fluctuations over time, resulting in a southern range contraction (it no longer occurs on St. Vincent, Barbados, or La Horquilla in the Los Hermanos Islands group allied with Venezuela; Arendt 2006a: Chapter 4, pages 66–67), and a northern range expansion among the larger Bahaman islands at higher latitudes (Arendt 2006a: Chapter 4, pages 67–73, Arendt 2006b; Appendix 3, Table 1, pages 385–395).

The species has undergone significant intra-island population increases within the past 30 to 60 years in Puerto Rico, Montserrat, and Bonaire. Conversely, over a 15-yr period (1989–2004) a population reduction was documented within two forest types (palo colorado and tabonuco) within the Luquillo Experimental Forest, Puerto Rico (Arendt 2006a: Chapter 1, Figure 1.18, page 19).

Fossil history

As a result of mitochondrial DNA analyses, the pearly-eye is thought to have originated 4 to 5 million years ago, i.e., as early as the beginning of the Pliocene (Ricklefs and Bermingham 1997), and may be the best plausible example of an autochthonous (indigenous) radiation in the Lesser Antilles (Hunt et al. 2001). However, the first evidence of the prehistoric occurrence of the pearly-eye anywhere in the Caribbean dates back only to about 2,000 years ago, and comes from bone fragments at an archaeological site located near Trant’s Bay, Montserrat, in the Lesser Antilles (Steadman et al. 1984b). Fossilized bones of the pearly-eye have been found in late Holocene deposits from the Burma Quarry, Antigua, Lesser Antilles (Pregill et al. 1988, Steadman et al. 1984a).

Distribution of the Pearly-eyed Thrasher - Range Map
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  • Year-round
  • Migration
  • Breeding
  • Non-Breeding
Distribution of the Pearly-eyed Thrasher

Recommended Citation

Arendt, W. J. (2017). Pearly-eyed Thrasher (Margarops fuscatus), version 1.0. In Neotropical Birds Online (T. S. Schulenberg, Editor). Cornell Lab of Ornithology, Ithaca, NY, USA. https://doi.org/10.2173/nb.peethr1.01