Masked Yellowthroat
Encyclopedia
The Masked Yellowthroat, Geothlypis aequinoctialis, is a New World warbler
. It has a number of separate resident breeding populations in Central
and South America
, some of which may be considered to form separate species.
The breeding habitat is marsh
es and other wet areas with dense low vegetation. The Masked Yellowthroat may also be found in other areas with dense shrub, but is less common in drier habitats. Two white eggs with reddish-brown markings are laid in a lined cup nest low in grass or rank vegetation.
The Masked Yellowthroat is 13.2 cm long and weighs 13 g. It has yellow-green upperparts, bright yellow underparts, and a mainly black bill. The adult male has a black facemask, bordered above with a grey band. The female is similar, but lacks the black mask. She is slightly duller, has variable amounts of grey to the head (often virtually none), a yellowish eyering and a yellowish stripe from the bill to the eye. There are significant racial variations in the male plumage
(see Taxonomy).
This species is easily distinguished from wintering
Common Yellowthroat
by its uniform yellow underparts, whereas the North America
n bird has a white belly.
The Masked Yellowthroat is usually seen in pairs, and does not associate with other species. It is often skulking, but may pop up occasionally, especially to sing. It feeds on insect
s, including caterpillars, which are usually captured in dense vegetation. The call is a fast chattering, quite unlike that of other yellowthroat species, and a more typical sharp chip.
This species may be spreading in Central America due to deforestation
.
of the Masked Yellowthroat, differing in size, male head pattern and song. The Central American subspecies is sometimes considered a separate species, and the two Pacific subspecies together are also often treated as a species. Recent genetic
evidence suggests that the southern South American subspecies may also merit specific status. The populations are as follows:
It is likely that the range of this species was once continuous, perhaps in the cooler conditions of the last ice age, but the populations are now separated by the dense sections of wet lowland forests of the Amazon
and Chocó. The auriculata and chiriquensis groups are further separated from the nominate and velata groups by the Andes Mountains.
New World warbler
The New World warblers or wood-warblers are a group of small, often colorful, passerine birds restricted to the New World. They are not related to the Old World warblers or the Australian warblers....
. It has a number of separate resident breeding populations in Central
Central America
Central America is the central geographic region of the Americas. It is the southernmost, isthmian portion of the North American continent, which connects with South America on the southeast. When considered part of the unified continental model, it is considered a subcontinent...
and 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...
, some of which may be considered to form separate species.
The breeding habitat is marsh
Marsh
In geography, a marsh, or morass, is a type of wetland that is subject to frequent or continuous flood. Typically the water is shallow and features grasses, rushes, reeds, typhas, sedges, other herbaceous plants, and moss....
es and other wet areas with dense low vegetation. The Masked Yellowthroat may also be found in other areas with dense shrub, but is less common in drier habitats. Two white eggs with reddish-brown markings are laid in a lined cup nest low in grass or rank vegetation.
The Masked Yellowthroat is 13.2 cm long and weighs 13 g. It has yellow-green upperparts, bright yellow underparts, and a mainly black bill. The adult male has a black facemask, bordered above with a grey band. The female is similar, but lacks the black mask. She is slightly duller, has variable amounts of grey to the head (often virtually none), a yellowish eyering and a yellowish stripe from the bill to the eye. There are significant racial variations in the male 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...
(see Taxonomy).
This species is easily distinguished from wintering
Bird migration
Bird migration is the regular seasonal journey undertaken by many species of birds. Bird movements include those made in response to changes in food availability, habitat or weather. Sometimes, journeys are not termed "true migration" because they are irregular or in only one direction...
Common Yellowthroat
Common Yellowthroat
The Common Yellowthroat is a New World warbler. They are abundant breeders in North America, ranging from southern Canada to central Mexico....
by its uniform yellow underparts, whereas the North America
North America
North America is a continent wholly within the Northern Hemisphere and almost wholly within the Western Hemisphere. It is also considered a northern subcontinent of the Americas...
n bird has a white belly.
The Masked Yellowthroat is usually seen in pairs, and does not associate with other species. It is often skulking, but may pop up occasionally, especially to sing. It feeds on insect
Insect
Insects are a class of living creatures within the arthropods that have a chitinous exoskeleton, a three-part body , three pairs of jointed legs, compound eyes, and two antennae...
s, including caterpillars, which are usually captured in dense vegetation. The call is a fast chattering, quite unlike that of other yellowthroat species, and a more typical sharp chip.
This species may be spreading in Central America due to deforestation
Deforestation
Deforestation is the removal of a forest or stand of trees where the land is thereafter converted to a nonforest use. Examples of deforestation include conversion of forestland to farms, ranches, or urban use....
.
Taxonomy
There are five 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...
of the Masked Yellowthroat, differing in size, male head pattern and song. The Central American subspecies is sometimes considered a separate species, and the two Pacific subspecies together are also often treated as a species. Recent genetic
Genetics
Genetics , a discipline of biology, is the science of genes, heredity, and variation in living organisms....
evidence suggests that the southern South American subspecies may also merit specific status. The populations are as follows:
- The nominate race, G. a. aequinoctialis, described above, breeds from central ColombiaColombiaColombia, officially the Republic of Colombia , is a unitary constitutional republic comprising thirty-two departments. The country is located in northwestern South America, bordered to the east by Venezuela and Brazil; to the south by Ecuador and Peru; to the north by the Caribbean Sea; to the...
, through northern VenezuelaVenezuelaVenezuela , officially called the Bolivarian Republic of Venezuela , is a tropical country on the northern coast of South America. It borders Colombia to the west, Guyana to the east, and Brazil to the south...
, TrinidadTrinidadTrinidad is the larger and more populous of the two major islands and numerous landforms which make up the island nation of Trinidad and Tobago. It is the southernmost island in the Caribbean and lies just off the northeastern coast of Venezuela. With an area of it is also the fifth largest in...
, the Guianas, to the regions near the Amazon RiverAmazon RiverThe Amazon of South America is the second longest river in the world and by far the largest by waterflow with an average discharge greater than the next seven largest rivers combined...
in BrazilBrazilBrazil , officially the Federative Republic of Brazil , is the largest country in South America. It is the world's fifth largest country, both by geographical area and by population with over 192 million people...
. The song is a warbled tee-chee-chee teecheweet teecheweet. - G. (a). velata, the “Southern Yellowthroat”, breeds in central South America from south-eastern PeruPeruPeru , 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....
and adjacent parts of Brazil, through BoliviaBoliviaBolivia officially known as Plurinational State of Bolivia , is a landlocked country in central South America. It is the poorest country in South America...
, ParaguayParaguayParaguay , 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...
, UruguayUruguayUruguay ,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...
and southern Brazil, to central ArgentinaArgentinaArgentina , 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...
. It is slightly smaller than aequinoctialis, and the male has a narrower black mask, with a broader grey band which extends onto the nape and neck sides. The song is longer, faster and more warbled than that of the northern race. - G. (a). auriculata and G. a. peruviana, the “Black-lored Yellowthroat”, breeds in western EcuadorEcuadorEcuador , officially the Republic of Ecuador is a representative democratic republic in South America, bordered by Colombia on the north, Peru on the east and south, and by the Pacific Ocean to the west. It is one of only two countries in South America, along with Chile, that do not have a border...
and western Peru. The male has the black mask restricted to the area from the bill back to the eye and a narrow band on the forehead. The subspecies peruviana, which is found in the MarañónMarañón RiverThe Marañón River rises about 160 km to the northeast of Lima, Peru, flows through a deeply-eroded Andean valley in a northwesterly direction, along the eastern base of the Cordillera of the Andes, as far as 5 degrees 36' southern latitude; then it makes a great bend to the northeast, and...
valley, is similar in size to aequinoctialis, but auriculata is noticeably smaller. The song of is a cheerful wee wee wee weeyou weeyou. - G. (a). chiriquensis, the “Chiriqui Yellowthroat”, occurs in western PanamaPanamaPanama , officially the Republic of Panama , is the southernmost country of Central America. Situated on the isthmus connecting North and South America, it is bordered by Costa Rica to the northwest, Colombia to the southeast, the Caribbean Sea to the north and the Pacific Ocean to the south. The...
and Costa RicaCosta RicaCosta Rica , officially the Republic of Costa Rica is a multilingual, multiethnic and multicultural country in Central America, bordered by Nicaragua to the north, Panama to the southeast, the Pacific Ocean to the west and the Caribbean Sea to the east....
. It is another small form, but the male has the broadest black mask of all the races, extending on to the forecrown. The song is similar to auriculata, but repeated many times, becoming faster, higher and weaker before a final flourish, and it may be given in flight.
It is likely that the range of this species was once continuous, perhaps in the cooler conditions of the last ice age, but the populations are now separated by the dense sections of wet lowland forests of the Amazon
Amazon Rainforest
The Amazon Rainforest , also known in English as Amazonia or the Amazon Jungle, is a moist broadleaf forest that covers most of the Amazon Basin of South America...
and Chocó. The auriculata and chiriquensis groups are further separated from the nominate and velata groups by the Andes Mountains.