Southern Beardless Tyrannulet
Encyclopedia
The Southern Beardless Tyrannulet, Camptostoma obsoletum, is a small passerine
bird
in the tyrant flycatcher
family
. It breeds from Costa Rica
through South America
south to Paraguay
, Bolivia
, and Argentina
.
. The head is dark brown or grey with an erectile crest and pale supercilium
. The upperparts are grey-green becoming paler on the rump. The wings are brown with yellow feather-edging and two whitish, yellowish or cinnamon wing bars. The tail, which regularly is held cocked, is brown, the throat grey, the breast yellowish, and the abdomen yellow. The bill is black, but at least the base of the lower mandible is pale.
Subspecies
from humid regions (e.g. the Amazon basin
) are generally greener with pure yellow bellies, while subspecies of drier regions (e.g. eastern Brazil
and western Ecuador
) generally are greyer with duller bellies. The subspecies C. o. venezuelae occurs only in Trinidad
and Venezuela
, and is well distinct in plumage tone.
The call is a loud whistled TLEEE-tee-tee-tee. In courtship, the crests are raised, the tail flicked, and an excited mixture of the TLEE call and a churring pee-chrrr-pee-chrrr is given.
Sexes are similar, and this species always appears brighter, especially with regard to the wing bars, than the closely related Northern Beardless Tyrannulet
(C. imberbe), with which it was once considered conspecific. However, the two forms overlap without interbreeding in central Costa Rica.
savanna
. Southern Beardless Tyrannulets are active birds, feeding in a vireo
- or warbler
-like fashion on insect
s, spider
s and berries
. Animal prey is either picked out of the air or off plants with a dedicated sally flight
, or gleaned
from vegetation. Fruit, e.g. from Alchornea glandulosa
, are typically picked off when perched or during hovering flight. This species will readily mob small predators like the Ferruginous Pygmy-owl (Glaucidium brasilianum). It tends to keep on its own except during the breeding season, and rarely joins mixed-species feeding flock
s.
The domed nest is made of plant fibre or leaves with a side entrance. The nest is placed by a tree fork, usually near a wasp
nest, which presumably provides some protection from predators. The typical clutch is two white eggs, which are marked with rufous and lilac mostly at the larger end. Incubation by the female is 14-15 days to hatching, with another 17 days to fledging.
As it ranges so widely, this bird is considered a Species of Least Concern
by the IUCN.
Passerine
A passerine is a bird of the order Passeriformes, which includes more than half of all bird species. Sometimes known as perching birds or, less accurately, as songbirds, the passerines form one of the most diverse terrestrial vertebrate orders: with over 5,000 identified species, it has roughly...
bird
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 tyrant flycatcher
Tyrant flycatcher
The tyrant flycatchers are a family of passerine birds which occur throughout North and South America. They are considered the largest family of birds on Earth, with more than 400 species. They are the most diverse avian family in every country in the Americas, except for the United States and...
family
Family (biology)
In biological classification, family is* a taxonomic rank. Other well-known ranks are life, domain, kingdom, phylum, class, order, genus, and species, with family fitting between order and genus. As for the other well-known ranks, there is the option of an immediately lower rank, indicated by the...
. It breeds from Costa Rica
Costa Rica
Costa 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....
through 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...
south to 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...
, 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 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...
.
Description
The Southern Beardless Tyrannulet is 10.2 cm long, weighs 7.5g and often resembles a tiny Yellow-bellied ElaeniaYellow-bellied Elaenia
The Yellow-bellied Elaenia, Elaenia flavogaster, is a small bird of the tyrant flycatcher family. It breeds from southern Mexico and the Yucatán Peninsula through Central and South America as far as northern Argentina, and on Trinidad and Tobago....
. The head is dark brown or grey with an erectile crest and pale supercilium
Supercilium
The supercilium is a plumage feature found on the heads of some bird species. It is a stripe which runs from the base of the bird's beak above its eye, finishing somewhere towards the rear of the bird's head. Also known as an "eyebrow", it is distinct from the eyestripe, which is a line which runs...
. The upperparts are grey-green becoming paler on the rump. The wings are brown with yellow feather-edging and two whitish, yellowish or cinnamon wing bars. The tail, which regularly is held cocked, is brown, the throat grey, the breast yellowish, and the abdomen yellow. The bill is black, but at least the base of the lower mandible is pale.
Subspecies
Subspecies
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...
from humid regions (e.g. the Amazon basin
Amazon Basin
The Amazon Basin is the part of South America drained by the Amazon River and its tributaries that drains an area of about , or roughly 40 percent of South America. The basin is located in the countries of Bolivia, Brazil, Colombia, Ecuador, Guyana, Peru, and Venezuela...
) are generally greener with pure yellow bellies, while subspecies of drier regions (e.g. eastern Brazil
Brazil
Brazil , 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...
and western Ecuador
Ecuador
Ecuador , 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...
) generally are greyer with duller bellies. The subspecies C. o. venezuelae occurs only in Trinidad
Trinidad
Trinidad 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...
and Venezuela
Venezuela
Venezuela , 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...
, and is well distinct in plumage tone.
The call is a loud whistled TLEEE-tee-tee-tee. In courtship, the crests are raised, the tail flicked, and an excited mixture of the TLEE call and a churring pee-chrrr-pee-chrrr is given.
Sexes are similar, and this species always appears brighter, especially with regard to the wing bars, than the closely related Northern Beardless Tyrannulet
Northern Beardless Tyrannulet
The Northern Beardless Tyrannulet, Camptostoma imberbe, is a small passerine bird in the tyrant flycatcher family. It breeds from southeasternmost Arizona and Texas of the United States through Mexico and Central America to northwestern Costa Rica....
(C. imberbe), with which it was once considered conspecific. However, the two forms overlap without interbreeding in central Costa Rica.
Ecology
This species is found in light forests, cultivation, gardens with trees and dry cerradoCerrado
The Cerrado, is a vast tropical savanna ecoregion of Brazil, particularly in the states of Gioas and Minas Gerais...
savanna
Savanna
A savanna, or savannah, is a grassland ecosystem characterized by the trees being sufficiently small or widely spaced so that the canopy does not close. The open canopy allows sufficient light to reach the ground to support an unbroken herbaceous layer consisting primarily of C4 grasses.Some...
. Southern Beardless Tyrannulets are active birds, feeding in a vireo
Vireo
The vireos are a group of small to medium-sized passerine birds restricted to the New World. They are typically dull-plumaged and greenish in color, the smaller species resembling wood warblers apart from their heavier bills...
- or warbler
Warbler
There are a number of Passeriformes called "warblers". They are not particularly closely related, but share some characteristics, such as being fairly small, vocal and insectivorous....
-like fashion 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, spider
Spider
Spiders are air-breathing arthropods that have eight legs, and chelicerae with fangs that inject venom. They are the largest order of arachnids and rank seventh in total species diversity among all other groups of organisms...
s and berries
Berry
The botanical definition of a berry is a fleshy fruit produced from a single ovary. Grapes are an example. The berry is the most common type of fleshy fruit in which the entire ovary wall ripens into an edible pericarp. They may have one or more carpels with a thin covering and fleshy interiors....
. Animal prey is either picked out of the air or off plants with a dedicated sally flight
Hawking (birds)
Hawking is a feeding strategy in birds involving catching flying insects in the air. The term usually refers to a technique of sallying out from a perch to snatch an insect and then returning to the same or a different perch...
, or gleaned
Gleaning (birds)
Gleaning is a term for a feeding strategy by birds in which they catch invertebrate prey, mainly arthropods, by plucking them from foliage or the ground, from crevices such as rock faces and under the eaves of houses, or even, as in the case of ticks and lice, from living animals. This behavior is...
from vegetation. Fruit, e.g. from Alchornea glandulosa
Alchornea glandulosa
Alchornea glandulosa is a tree species of the Acalyphoideae native to South America, growing for example in southern Brazil from Minas Gerais to Rio Grande do Sul. It is locally known as tamanqueiro, tapiá or amor seco. This gnarled tree grows preferentially in riparian forest, where it a common...
, are typically picked off when perched or during hovering flight. This species will readily mob small predators like the Ferruginous Pygmy-owl (Glaucidium brasilianum). It tends to keep on its own except during the breeding season, and rarely joins mixed-species feeding flock
Mixed-species feeding flock
A mixed-species feeding flock, also termed a mixed-species foraging flock, mixed hunting party or informally bird wave, is a flock of usually insectivorous birds of different species, that join each other and move together while foraging...
s.
The domed nest is made of plant fibre or leaves with a side entrance. The nest is placed by a tree fork, usually near a wasp
Wasp
The term wasp is typically defined as any insect of the order Hymenoptera and suborder Apocrita that is neither a bee nor an ant. Almost every pest insect species has at least one wasp species that preys upon it or parasitizes it, making wasps critically important in natural control of their...
nest, which presumably provides some protection from predators. The typical clutch is two white eggs, which are marked with rufous and lilac mostly at the larger end. Incubation by the female is 14-15 days to hatching, with another 17 days to fledging.
As it ranges so widely, this bird is considered a Species 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 the IUCN.
External links
- Southern Beardless-Tyrannulet photo gallery VIREO Photo-High Res
- Southern Beardless-Tyrannulet: photos, vocalizations The Avifauna of the Interior of Ceará, Brazil.