Tawny-throated Leaftosser
Encyclopedia
The Tawny-throated Leaftosser (Sclerurus mexicanus) is a tropical American
Americas
The Americas, or America , are lands in the Western hemisphere, also known as the New World. In English, the plural form the Americas is often used to refer to the landmasses of North America and South America with their associated islands and regions, while the singular form America is primarily...

 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...

 species
Species
In biology, a species is one of the basic units of biological classification and a taxonomic rank. A species is often defined as a group of organisms capable of interbreeding and producing fertile offspring. While in many cases this definition is adequate, more precise or differing measures are...

 in the ovenbird 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...

 Furnariidae. It is also known as the Tawny-throated Leafscraper, Mexican Leaftosser or Mexican Leafscraper. This bird might be a cryptic species complex
Cryptic species complex
In biology, a cryptic species complex is a group of species which satisfy the biological definition of species—that is, they are reproductively isolated from each other—but whose morphology is very similar ....

.

Description

This roughly thrush
Thrush (bird)
The thrushes, family Turdidae, are a group of passerine birds that occur worldwide.-Characteristics:Thrushes are plump, soft-plumaged, small to medium-sized birds, inhabiting wooded areas, and often feed on the ground or eat small fruit. The smallest thrush may be the Forest Rock-thrush, at and...

-sized bird measures 15–17 cm in length and weighs 24–30 g. Its coloration is quite uniformly a rich chestnut brown. The tail is darker, the breast, rump and head are lighter and tinged rufous, though the crown and cheek region are as dark as the body, with some greyish hue to the cheeks. Its iris
Iris (anatomy)
The iris is a thin, circular structure in the eye, responsible for controlling the diameter and size of the pupils and thus the amount of light reaching the retina. "Eye color" is the color of the iris, which can be green, blue, or brown. In some cases it can be hazel , grey, violet, or even pink...

 is dusky brown, the feet are blackish brown. The bill is very long and thin, perhaps by proportion the longest and thinnest of all Furnariidae. It is blackish brown above, and whitish, horn-colored or dark grey below; the tip is black.

Males and females look alike. Young birds are duller, with light streaks and dusky scaling on throat and breast.

The song of the Tawny-throated Leaftosser is a series of 4–9 wheezy notes which descend, accelerate and fade out as they are given: peeeeee-peeeee-peeee-chrrrr. For some populations, slightly different songs have been described; subspecies pullus produces a series of sharp squee calls or a whistling pseeer-pseer-pseer-psee-pse, while subspecies peruvianus has a series of clear suweet whistles and its song often ends in a trill. It is not clear whether these vocalizations indicate specific distinctiveness, but it is notable that at least in peruvianus the song often ends with a "flourish" and does not quietly fade out as it does in the northern populations.

The alarm call is a sharp chick, squee, tseeéét or zick.

The Short-billed Leaftosser
Short-billed Leaftosser
The Short-billed Leaftosser is a species of bird in the Furnariidae family.It is found in Bolivia, Brazil, Colombia, Ecuador, French Guiana, Guyana, Peru, Suriname, and Venezuela....

 (S. rufigularis) is widely sympatric in the Amazonas
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...

 basin. It looks almost alike but it has a shorter bill and its song, while structured similarly, changes in pitch several times through its course rather than simply descending. It is also an inhabitant of terra firme forest near rivers, whereas the Tawny-throated Leaftosser prefers hilly terrain.

Systematics

The Tawny-throated Leaftosser is considered to be the sister species of the Short-billed Leaftosser
Short-billed Leaftosser
The Short-billed Leaftosser is a species of bird in the Furnariidae family.It is found in Bolivia, Brazil, Colombia, Ecuador, French Guiana, Guyana, Peru, Suriname, and Venezuela....

 (S. rufigularis). It might actually contain two species which are sympatric by range (though not by altitude) between eastern Panama
Panama
Panama , 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 northern Colombia
Colombia
Colombia, 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...

; the birds between Meta
Meta Department
Meta is a department of Colombia. It is close to the geographic center of the country, to the east of the Andean mountains. A large portion of the department, which is also crossed by the Meta River, is covered by a grassland plain known as the Llanos. Its capital is Villavicencio...

 and Santander Department
Santander Department
Santander is a department of Colombia. Santander inherited the name of one of the nine original states of the United States of Colombia. It is located in the central northern part of the country, east of the Magdalena River, bordered to the south and southeast by Boyacá, to the northeast by Norte...

s (Colombia), including a population in the Serranía de las Quinchas
Serranía de las Quinchas
The Serranía de las Quinchas is an 860 km2 area of tropical rainforest and cloud forest in Colombia. It lies in the mid Magdalena River Valley in the foothills of the Cordillera Oriental of the Colombian Andes. It ranges in altitude from 200 m to 1700 m asl...

 discovered only on January 20, 2006, have not been identified as to subspecies yet. As regards scientific names, S. mexicanus would refer to the lowland birds, while the name of the Andean
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...

 ones (which ironically would not include the 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...

 andinus, essentially a lowland bird despite its name) would be S. obscurior. The status of the isolated Mata Atlântica
Mata Atlântica
The Atlantic Forest is a region of tropical and subtropical moist forest, tropical dry forest, tropical savanna, semi deciduous forest and mangrove forests which extends along the Atlantic coast of Brazil from Rio Grande do Norte state in the north to Rio Grande do Sul state in the south, and...

 population is also unclear; it might represent yet another species, which would be named S. bahiae, but it has been very little studied.

Subspecies

As long as the species is not split up, seven 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...

, differing in appearance quite markedly for such a plain bird, are recognized.

mexicanus group:
  • Sclerurus mexicanus mexicanus P.L.Sclater, 1857Veracruz
    Veracruz
    Veracruz, formally Veracruz de Ignacio de la Llave officially Estado Libre y Soberano de Veracruz de Ignacio de la Llave , is one of the 31 states that, along with the Federal District, comprise the 32 federative entities of Mexico. It is divided in 212 municipalities and its capital city is...

     (SE Mexico
    Mexico
    The United Mexican States , commonly known as Mexico , is a federal constitutional republic in North America. It is bordered on the north by the United States; on the south and west by the Pacific Ocean; on the southeast by Guatemala, Belize, and the Caribbean Sea; and on the east by the Gulf of...

    ) to N Nicaragua
    Nicaragua
    Nicaragua is the largest country in the Central American American isthmus, bordered by Honduras to the north and Costa Rica to the south. The country is situated between 11 and 14 degrees north of the Equator in the Northern Hemisphere, which places it entirely within the tropics. The Pacific Ocean...

    . First recorded in El Salvador
    El Salvador
    El Salvador or simply Salvador is the smallest and the most densely populated country in Central America. The country's capital city and largest city is San Salvador; Santa Ana and San Miguel are also important cultural and commercial centers in the country and in all of Central America...

     on June 12, 1998, but nesting not confirmed. Includes
    S. m. certus.
Neither dark nor rufous hues very pronounced, but dark and rufous areas clearly contrasting.
  • Sclerurus mexicanus pullus Bangs, 1902 – Highlands 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....

     to Coclé and Veraguas (W Panama
    Panama
    Panama , 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...

    ).
Generally darker and less rufous than mexicanus, but throat lighter and rump with pronounced rufous hue.
  • Sclerurus mexicanus andinus Chapman, 1914 – Lowlands of Panamá Province
    Panamá Province
    Panamá is a major province of the country of Panama, containing the capital city, Panama City. The governor of the province is Mayin Correa, a former mayor of Panama City and elected by President Martinelli after being sworn in on July 1, 2009.-Districts:...

     (E Panama) to N Colombia, perhaps including Santander Department; from there northeast to the Serranía del Perijá
    Serrania del Perija
    The Serranía del Perijá, Cordillera de Perijá or Sierra de Perijá is a mountain range, an extension of the eastern Andean branch , in northern South America, between Colombia and Venezuela, ending further north in the Guajira Desert, a total distance of about 310 km...

     of 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 southeast through S Venezuela to the Gran Sabana and W Guyana
    Guyana
    Guyana , officially the Co-operative Republic of Guyana, previously the colony of British Guiana, is a sovereign state on the northern coast of South America that is culturally part of the Anglophone Caribbean. Guyana was a former colony of the Dutch and of the British...

    .
Lighter than mexicanus, rump and uppertail coverts very rufous.
  • Sclerurus mexicanus macconnelli Chubb, 1919 – Guianas, Rio Negro and Tapajós
    Tapajós
    The Tapajós, a Brazilian river running through a humid and hot valley, pours into the Amazon River 500 miles above Pará and is about 1200 miles long.It rises on the lofty Brazilian plateau near Diamantino in 14 degrees 25' south latitude...

     E to Maranhão
    Maranhão
    Maranhão is a northeastern state of Brazil. To the north lies the Atlantic Ocean. Maranhão is neighbored by the states of Piauí, Tocantins and Pará. The people of Maranhão have a distinctive accent...

    , S to N Mato Grosso
    Mato Grosso
    Mato Grosso is one of the states of Brazil, the third largest in area, located in the western part of the country.Neighboring states are Rondônia, Amazonas, Pará, Tocantins, Goiás and Mato Grosso do Sul. It also borders Bolivia to the southwest...

     states (Brazil).
Similar to mexicanus, but more olive-brown; rufous on throat and rump very pronounced, extending onto chest.

obscurior
group:
  • Sclerurus mexicanus obscurior (or S. obscurior obscurior) Hartert, 1901 – Highlands from Isthmus of Panama
    Isthmus of Panama
    The Isthmus of Panama, also historically known as the Isthmus of Darien, is the narrow strip of land that lies between the Caribbean Sea and the Pacific Ocean, linking North and South America. It contains the country of Panama and the Panama Canal...

     (Cerro Malí, Cerro Pirre, Cerro Tacarcuna) through Cordillera Occidental of Colombia to El Oro
    El Oro Province
    El Oro province is the southernmost of Ecuador's coastal provinces. It was named for its historically important gold production. Today it is one of the world's major exporters of bananas. The capital is Machala.-Geography:To the north and east the province has borders with the provinces Guayas,...

     and W Loja
    Loja Province
    Loja Province is one of 24 provinces in Ecuador and shares its southern border on the west by El Oro Province, on the north by El Azuay, and on the east by Zamora-Chinchipe. Founded on its present site in 1548 by Captain Alonso de Mercadillo the site had been previously moved and rebuilt from La...

     provinces in SW 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...

    . S. m. anomalus, described from Cerro Sapo (Panama), is not recognizably distinct; presumably it belongs to obscurior
Darker and less rufous than mexicanus.
  • Sclerurus mexicanus peruvianus (or Sclerurus obscurior peruvianus) Chubb, 1919 – Cordillera Oriental south from W Meta Department
    Meta Department
    Meta is a department of Colombia. It is close to the geographic center of the country, to the east of the Andean mountains. A large portion of the department, which is also crossed by the Meta River, is covered by a grassland plain known as the Llanos. Its capital is Villavicencio...

     – perhaps from as far north as Santander Department
    Santander Department
    Santander is a department of Colombia. Santander inherited the name of one of the nine original states of the United States of Colombia. It is located in the central northern part of the country, east of the Magdalena River, bordered to the south and southeast by Boyacá, to the northeast by Norte...

     – (Colombia), adjacent Amazonas basin (Amazonas, Acre
    Acre (state)
    Acre is one of the 27 states of Brazil. It is situated in the southwest of the Northern Region, bordering Amazonas to the north, Rondônia to the east, Bolivia to the southeast and the Ucayali Region of Peru to the south and west. It occupies an area of 152,581.4 km2, being slightly smaller...

     N Rondônia
    Rondônia
    Rondônia is a state in Brazil, located in the north-western part of the country. To the west is a short border with the state of Acre, to the north is the state of Amazonas, in the east is Mato Grosso, and in the south is Bolivia. Its capital is Porto Velho. The state was named after Candido Rondon...

     states in NW 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...

    ), to E 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....

     and NW Santa Cruz Department
    Santa Cruz Department
    Santa Cruz, with an area of 370,621 km², is the largest of the nine constituent departments of Bolivia. In the 2001 census, it reported a population of 2,029,471. The capital is the city of Santa Cruz de la Sierra. The state is one of the wealthiest states in Bolivia with huge reserves of...

     (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...

    ).
Generally like obscurior, but even less rufous.

Incertae sedis
Incertae sedis
, is a term used to define a taxonomic group where its broader relationships are unknown or undefined. Uncertainty at specific taxonomic levels is attributed by , , and similar terms.-Examples:*The fossil plant Paradinandra suecica could not be assigned to any...

:
  • Sclerurus mexicanus bahiae (or Sclerurus bahiae) Chubb, 1919 – Atlantic Forest of Brazil, from 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...

     to NE São Paulo
    São Paulo (state)
    São Paulo is a state in Brazil. It is the major industrial and economic powerhouse of the Brazilian economy. Named after Saint Paul, São Paulo has the largest population, industrial complex, and economic production in the country. It is the richest state in Brazil...

    .
Similar to pullus; rump rich rufous-brown, throat dark and contrasting little with breast.

Range and ecology

The Tawny-throated Leaftosser ranges from southern Mexico
Mexico
The United Mexican States , commonly known as Mexico , is a federal constitutional republic in North America. It is bordered on the north by the United States; on the south and west by the Pacific Ocean; on the southeast by Guatemala, Belize, and the Caribbean Sea; and on the east by the Gulf of...

 through Central America
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...

 into Colombia
Colombia
Colombia, 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...

, and from there south to the 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....

vian 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...

 as well as southeast to the Amazon Basin, with an isolated population in the Atlantic Forest of Brazil. The species is largely absent from 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 patchily distributed across most of its range, particularly Central America. Its natural habitat
Habitat
* Habitat , a place where a species lives and grows*Human habitat, a place where humans live, work or play** Space habitat, a space station intended as a permanent settlement...

s are tropical moist lowland forest
Forest
A forest, also referred to as a wood or the woods, is an area with a high density of trees. As with cities, depending where you are in the world, what is considered a forest may vary significantly in size and have various classification according to how and what of the forest is composed...

s and tropical moist montane evergreen forests. It prefers hill
Hill
A hill is a landform that extends above the surrounding terrain. Hills often have a distinct summit, although in areas with scarp/dip topography a hill may refer to a particular section of flat terrain without a massive summit A hill is a landform that extends above the surrounding terrain. Hills...

y terrain, occurring mainly between 700 and 2,200 m ASL
Above mean sea level
The term above mean sea level refers to the elevation or altitude of any object, relative to the average sea level datum. AMSL is used extensively in radio by engineers to determine the coverage area a station will be able to reach...

 in Central America, and from near sea level to 1,500 m and locally to 2,000 m ASL in South America.

The species lives on the ground, where it feeds on invertebrate
Invertebrate
An invertebrate is an animal without a backbone. The group includes 97% of all animal species – all animals except those in the chordate subphylum Vertebrata .Invertebrates form a paraphyletic group...

s found by flicking through leaf litter, digging in moist soil or in rotting wood, often using the tail to anchor itself; the tips of the rectrices become abraded by this behavior and before moult
Moult
In biology, moulting or molting , also known as sloughing, shedding, or for some species, ecdysis, is the manner in which an animal routinely casts off a part of its body , either at specific times of year, or at specific points in its life cycle.Moulting can involve the epidermis , pelage...

 often just the resilient feather shafts remain. Tawny-throated Leaftossers are encountered singly or in pairs; they may be attracted by recordings of their alarm calls. These birds typically move by hopping about and are reluctant to fly if they do not have to. They are not migratory
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...

.

Tawny-throated Leaftossers are assumed to be monogamous and are territorial, with their territories
Territory (animal)
In ethology the term territory refers to any sociographical area that an animal of a particular species consistently defends against conspecifics...

 that are around 25 ha in size. The breeding season – if this species actually has a well-marked breeding season – is prolonged, running at least from December to April in 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....

; breeding activity was recorded in April/May for Colombia and in August for 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...

. The nest is a small cup, loosely woven from dry twigs and leaf remains, in a cavity up to 20 cm in diameter at the end of a tunnel – up to 50 cm long but often much shorter – dug into an earth bank or similar spot. Little is known about their breeding biology, but they presumably lay two eggs per clutch
Clutch (eggs)
A clutch of eggs refers to all the eggs produced by birds or reptiles, often at a single time, particularly those laid in a nest.In birds, destruction of a clutch by predators, , results in double-clutching...

.

It is generally an uncommon bird, with a population density
Population density
Population density is a measurement of population per unit area or unit volume. It is frequently applied to living organisms, and particularly to humans...

 usually less than (and often far less than) 5 individuals per square kilometer. It quickly disappears from forests that have been fragmented due to logging, and will not even tolerate selective logging well. Due to its large overall range, it is classified as 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; if it is split up into two or three species
Species
In biology, a species is one of the basic units of biological classification and a taxonomic rank. A species is often defined as a group of organisms capable of interbreeding and producing fertile offspring. While in many cases this definition is adequate, more precise or differing measures are...

 however, the Andean
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...

 and Atlantic Forest populations are likely to qualify as threatened species
Threatened species
Threatened species are any speciesg animals, plants, fungi, etc.) which are vulnerable to endangerment in the near future.The World Conservation Union is the foremost authority on threatened species, and treats threatened species not as a single category, but as a group of three categories,...

.
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