The southern white-fringed antwren (Formicivora grisea) is an insectivorous bird in subfamily Thamnophilinae of family Thamnophilidae, the "typical antbirds". It is found in Brazil, Colombia, French Guiana, Guyana, Suriname, and Venezuela.
Taxonomy and systematics
The southern white-fringed antwren was described by the French polymath Georges-Louis Leclerc, Comte de Buffon in his Histoire Naturelle des Oiseaux in 1775 from a specimen collected in Cayenne, French Guiana. The bird was also illustrated in a hand-colored plate engraved by François-Nicolas Martinet in the Planches Enluminées D'Histoire Naturelle which was produced under the supervision of Edme-Louis Daubenton to accompany Buffon's text. Neither the plate caption nor Buffon's description included a scientific name but in 1783 the Dutch naturalist Pieter Boddaert coined the binomial name Turdus griseus in his catalogue of the Planches Enluminées. The southern white-fringed antwren is now placed in the genus Formicivora that was introduced by the English naturalist William Swainson in 1824.
What is now the northern white-fringed antwren (Formicivora intermedia) and the southern white-fringed antwren were previously considered conspecific as the white-fringed antwren Formicivora grisea. Worldwide taxonomic systems separated them based primarily on their very different vocalizations detailed in a 2016 publication, though the Clements taxonomy did not do so until 2023. The North and South American Classification Committees of the American Ornithological Society retain the single white-fringed antwren species, though the South American Committee is seeking a proposal to adopt the split.
The southern white-fringed antwren has two subspecies, the nominate F. g. grisea (Boddaert, 1783) and F. g. rufiventris (Carriker, 1936).
Distribution and habitat
The southern white-fringed antwren has a disjunct distribution. The nominate subspecies is found in northern Brazil and the Guianas and separately from there in much of Amazonian and eastern Brazil. Subspecies F. g. rufiventris is found from Meta and Caquetá departments in Colombia east into most of Venezuela's Amazonas state. The species inhabits a variety of wooded landscapes, where it favors the understorey to mid-storey at the forest's edges. Subspecies F. g. rufiventris mostly occurs in campina on white-sand soil or young secondary forest. The nominate subspecies occurs in mangroves in the Guianas, in second growth and riparian vegetation in Amazonian Brazil, in tropical deciduous forest in the interior of northeastern Brazil, and in restinga scrublands in coastal eastern Brazil. In elevation it mostly occurs below but reaches in Venezuela.
Breeding
The southern white-fringed antwren's breeding season varies greatly across its range, with differing periods between July and March. Its nest is a cup woven from grass stems and thin plant fibers suspended in a branch fork, typically above the ground; both sexes build it. The usual clutch size is two eggs, which are creamy or grayish white with variable markings of lilac to deep purple. The incubation period, time to fledging, and details of parental care are not known. -->
<!-- The Basto paper says their one specimen of this species was not infected. The Londono paper is a dead link
Of a total of 13 birds studied in Colombia—in the Parque Nacional de La Macarena and near Turbo—only one was infected with blood parasites (an undetermined Plasmodium species). -->