Variable Antshrike
Encyclopedia
The Variable Antshrike (Thamnophilus caerulescens) is a species of bird
in the Thamnophilidae family found widely in South America
. It is, as its common name
suggests, arguably the species of antbird
with the most variable plumage
, leading to speculations that it comprises more than one species, but presently available evidence suggests this assumption is incorrect.
where the males are primarily black), and white wing-bars that may appear spotty, especially on the lesser wing coverts. The tail is black with white tips (best visible from below). In the eastern, central and southern subspecies, the chest and most of the head are grey, the back is grey with variable amounts of black (may be almost entirely black), a semi-concealed white interscapular patch, and the crown is black (black crown reduced in far north-eastern Brazil). The variation in the colour of the belly and crissum is highly complex, ranging from white in some subspecies, over grey in others, to deep cinnamon. The male of the western subspecies melanochrous from the Andes
of Peru
is strikingly different, being overall black except for the white in its wings and tail. The male of the subspecies aspersiventer of the Andes in north-western Bolivia
and adjacent Peru approaches melanochrous in colour, but has dense white barring to the belly.
Females are equally variable. In most of this species range, their wings are blackish-brown with rufescent edging to the remiges, and white or buff wing-bars (often appears rather spotty). In north-eastern Brazil, however, the wing-bars are greatly reduced, and, in the population in Ceará
, to the extend where it essentially is lacking. The tail resembles that of the males, but is often more brownish. The underparts are rich orange-cinnamon, in a few subspecies extending as far up as the chest, but in most the chest is pale brownish or grey. The back is brown and the head is pure grey or pale grey tinged brown, while most subspecies have a brown crown, which, however, is black in parts of central Brazil and in the Andean subspecies melanochrous and aspersiventer. Both sexes of all subspecies have grey legs and a stubby bill that is grey below, blackish above. Some subspecies are easily confused with the slaty antshrikes, but these differ consistently in their broad white edging to the tertials.
The Variable Antshrike is found widely in eastern and southern Brazil, with disjunct
populations in Ceará, Pernambuco
and Alagoas
. From southern Brazil, its range extends through Uruguay
, Paraguay
, northern Argentina
, Bolivia, and along the eastern slope of the Andes in Peru, as far north as the Amazonas Region
.
It occurs in a wide range of densely to lightly wooded habitats, ranging from the edge of humid forest to arid woodland. In large parts of its range it can be found in lowlands, but it is primarily found in foothills in north-eastern Brazil, and is restricted to highlands up to 2600 meters (8500 ft), locally to 3000 m (9800 ft), throughout a large part of its Andean range.
It is generally common and consequently considered to be of least concern
by BirdLife International
and IUCN. The subspecies cearensis in far north-eastern Brazil is limited to a region with extensive habitat destruction
, and its status may give cause for concern.
antshrike. It is generally found singly or in pairs at low levels, often within dense undergrowth. Consequently, it can often be difficult to see it well. It feeds primarily on insects and other arthropod
s. Seeds and fruits have also been reported. While foraging, it is regularly seen "dipping" its tail and flicking its wings. Breeding is seasonal, but exact timing depends on the region. The nest is a woven cup, generally placed rather low. Both sexes incubate the 2-3 eggs.
and geneflow between various populations remains uninterrupted. The taxa in north-eastern Brazil, which also are relatively distinctive, were not included in these studies, and it therefore remains unclear if they are worthy of species recognition. Another problem relates to the variations within subspecies. The subspecies dinellii and cearensis, for example, are both variable, resulting in the description of additional subspecies for some sub-populations. If some of these are valid remains to be seen.
Bird
Birds are feathered, winged, bipedal, endothermic , egg-laying, vertebrate animals. Around 10,000 living species and 188 families makes them the most speciose class of tetrapod vertebrates. They inhabit ecosystems across the globe, from the Arctic to the Antarctic. Extant birds range in size from...
in the Thamnophilidae family found widely in South America
South America
South America is a continent situated in the Western Hemisphere, mostly in the Southern Hemisphere, with a relatively small portion in the Northern Hemisphere. The continent is also considered a subcontinent of the Americas. It is bordered on the west by the Pacific Ocean and on the north and east...
. It is, as its common name
Common name
A common name of a taxon or organism is a name in general use within a community; it is often contrasted with the scientific name for the same organism...
suggests, arguably the species of antbird
Antbird
The antbirds are a large family, Thamnophilidae, of passerine birds found across subtropical and tropical Central and South America, from Mexico to Argentina. There are more than 200 species, known variously as antshrikes, antwrens, antvireos, fire-eyes, bare-eyes and bushbirds...
with the most variable plumage
Plumage
Plumage refers both to the layer of feathers that cover a bird and the pattern, colour, and arrangement of those feathers. The pattern and colours of plumage vary between species and subspecies and can also vary between different age classes, sexes, and season. Within species there can also be a...
, leading to speculations that it comprises more than one species, but presently available evidence suggests this assumption is incorrect.
Description
The Variable Antshrike is a thickset bird with a total length of approximately 14 centimetre. The male has black wings with grey edging to the remiges (sometimes very narrow, and barely visible in the subspeciesSubspecies
Subspecies in biological classification, is either a taxonomic rank subordinate to species, ora taxonomic unit in that rank . A subspecies cannot be recognized in isolation: a species will either be recognized as having no subspecies at all or two or more, never just one...
where the males are primarily black), and white wing-bars that may appear spotty, especially on the lesser wing coverts. The tail is black with white tips (best visible from below). In the eastern, central and southern subspecies, the chest and most of the head are grey, the back is grey with variable amounts of black (may be almost entirely black), a semi-concealed white interscapular patch, and the crown is black (black crown reduced in far north-eastern Brazil). The variation in the colour of the belly and crissum is highly complex, ranging from white in some subspecies, over grey in others, to deep cinnamon. The male of the western subspecies melanochrous from the Andes
Andes
The Andes is the world's longest continental mountain range. It is a continual range of highlands along the western coast of South America. This range is about long, about to wide , and of an average height of about .Along its length, the Andes is split into several ranges, which are separated...
of Peru
Peru
Peru , officially the Republic of Peru , is a country in western South America. It is bordered on the north by Ecuador and Colombia, on the east by Brazil, on the southeast by Bolivia, on the south by Chile, and on the west by the Pacific Ocean....
is strikingly different, being overall black except for the white in its wings and tail. The male of the subspecies aspersiventer of the Andes in north-western Bolivia
Bolivia
Bolivia officially known as Plurinational State of Bolivia , is a landlocked country in central South America. It is the poorest country in South America...
and adjacent Peru approaches melanochrous in colour, but has dense white barring to the belly.
Ceará
Ceará is one of the 27 states of Brazil, located in the northeastern part of the country, on the Atlantic coast. It is currently the 8th largest Brazilian State by population and the 17th by area. It is also one of the main touristic destinations in Brazil. The state capital is the city of...
, to the extend where it essentially is lacking. The tail resembles that of the males, but is often more brownish. The underparts are rich orange-cinnamon, in a few subspecies extending as far up as the chest, but in most the chest is pale brownish or grey. The back is brown and the head is pure grey or pale grey tinged brown, while most subspecies have a brown crown, which, however, is black in parts of central Brazil and in the Andean subspecies melanochrous and aspersiventer. Both sexes of all subspecies have grey legs and a stubby bill that is grey below, blackish above. Some subspecies are easily confused with the slaty antshrikes, but these differ consistently in their broad white edging to the tertials.
Distribution, habitat and status
Disjunct distribution
In biology, a taxon with a disjunct distribution is one that has two or more groups that are related but widely separated from each other geographically...
populations in Ceará, Pernambuco
Pernambuco
Pernambuco is a state of Brazil, located in the Northeast region of the country. To the north are the states of Paraíba and Ceará, to the west is Piauí, to the south are Alagoas and Bahia, and to the east is the Atlantic Ocean. There are about of beaches, some of the most beautiful in the...
and Alagoas
Alagoas
Alagoas is one of the 27 federative units of Brazil and is situated in the eastern part of the Northeast Region. It borders: Pernambuco ; Sergipe ; Bahia ; and the Atlantic Ocean . It occupies an area of 27,767 km², being slightly larger than Haiti...
. From southern Brazil, its range extends through Uruguay
Uruguay
Uruguay ,officially the Oriental Republic of Uruguay,sometimes the Eastern Republic of Uruguay; ) is a country in the southeastern part of South America. It is home to some 3.5 million people, of whom 1.8 million live in the capital Montevideo and its metropolitan area...
, Paraguay
Paraguay
Paraguay , officially the Republic of Paraguay , is a landlocked country in South America. It is bordered by Argentina to the south and southwest, Brazil to the east and northeast, and Bolivia to the northwest. Paraguay lies on both banks of the Paraguay River, which runs through the center of the...
, northern Argentina
Argentina
Argentina , officially the Argentine Republic , is the second largest country in South America by land area, after Brazil. It is constituted as a federation of 23 provinces and an autonomous city, Buenos Aires...
, Bolivia, and along the eastern slope of the Andes in Peru, as far north as the Amazonas Region
Amazonas Region
Amazonas is a department of northern Peru bordered by Ecuador on the north and west, Cajamarca Department on the west, La Libertad Department on the south, and Loreto Department and San Martín Department on the east. Its capital is the city of Chachapoyas....
.
It occurs in a wide range of densely to lightly wooded habitats, ranging from the edge of humid forest to arid woodland. In large parts of its range it can be found in lowlands, but it is primarily found in foothills in north-eastern Brazil, and is restricted to highlands up to 2600 meters (8500 ft), locally to 3000 m (9800 ft), throughout a large part of its Andean range.
It is generally common and consequently considered to be of least concern
Least Concern
Least Concern is an IUCN category assigned to extant taxon or lower taxa which have been evaluated but do not qualify for any other category. As such they do not qualify as threatened, Near Threatened, or Conservation Dependent...
by BirdLife International
BirdLife International
BirdLife International is a global Partnership of conservation organisations that strives to conserve birds, their habitats and global biodiversity, working with people towards sustainability in the use of natural resources...
and IUCN. The subspecies cearensis in far north-eastern Brazil is limited to a region with extensive habitat destruction
Habitat destruction
Habitat destruction is the process in which natural habitat is rendered functionally unable to support the species present. In this process, the organisms that previously used the site are displaced or destroyed, reducing biodiversity. Habitat destruction by human activity mainly for the purpose of...
, and its status may give cause for concern.
Behavior
In terms of behavior, this is a typical ThamnophilusThamnophilus
Thamnophilus is a genus of antbird in the family Thamnophilidae. The species in this genus are commonly known as antshrikes. They are insectivores that feed by gleaning prey from foliage and are found in the Neotropics....
antshrike. It is generally found singly or in pairs at low levels, often within dense undergrowth. Consequently, it can often be difficult to see it well. It feeds primarily on insects and other arthropod
Arthropod
An arthropod is an invertebrate animal having an exoskeleton , a segmented body, and jointed appendages. Arthropods are members of the phylum Arthropoda , and include the insects, arachnids, crustaceans, and others...
s. Seeds and fruits have also been reported. While foraging, it is regularly seen "dipping" its tail and flicking its wings. Breeding is seasonal, but exact timing depends on the region. The nest is a woven cup, generally placed rather low. Both sexes incubate the 2-3 eggs.
Taxonomy
Its highly variable plumage, some variations in the voice, and its unusual distribution have resulted in widespread speculations that it involves more than one species. Studies involving mtDNA and voice of the Bolivian populations, which is a meeting point for several of the distinctly different subspecies, did not support the theory of several species, instead suggesting that much of the vocal variation is clinalCline (population genetics)
In biology, an ecocline or simply cline describes an ecotone in which a series of biocommunities display continuous gradient...
and geneflow between various populations remains uninterrupted. The taxa in north-eastern Brazil, which also are relatively distinctive, were not included in these studies, and it therefore remains unclear if they are worthy of species recognition. Another problem relates to the variations within subspecies. The subspecies dinellii and cearensis, for example, are both variable, resulting in the description of additional subspecies for some sub-populations. If some of these are valid remains to be seen.