The rufous-thighed kite (''Harpagus diodon'') is a species of

bird of prey Birds of prey or predatory birds, also known as raptors, are hypercarnivorous bird species that actively hunt and feed on other vertebrates (mainly mammals, reptiles and other smaller birds). In addition to speed and strength, these predators h ...

subfamily In biological classification, a subfamily (Latin: ', plural ') is an auxiliary (intermediate) taxonomic rank, next below family but more inclusive than genus. Standard nomenclature rules end subfamily botanical names with "-oideae", and zoologi ...

Accipitrinae The Accipitrinae are the subfamily of the Accipitridae often known as the "true" hawks, including all members of ''Accipiter'' and the closely related genera ''Microspizias'', ''Erythrotriorchis'', and '' Megatriorchis''. The large and widespre ...

, the "true" hawks, of family

Accipitridae The Accipitridae is one of the three families within the order Accipitriformes, and is a family of small to large birds with strongly hooked bills and variable morphology based on diet. They feed on a range of prey items from insects to medium-s ...

.Remsen, J. V., Jr., J. I. Areta, E. Bonaccorso, S. Claramunt, A. Jaramillo, D. F. Lane, J. F. Pacheco, M. B. Robbins, F. G. Stiles, and K. J. Zimmer. Version 24 July 2022. A classification of the bird species of South America. American Ornithological Society. https://www.museum.lsu.edu/~Remsen/SACCBaseline.htm retrieved July 24, 2022 It is found regularly in

Argentina Argentina (), officially the Argentine Republic ( es, link=no, República Argentina), is a country in the southern half of South America. Argentina covers an area of , making it the second-largest country in South America after Brazil, th ...

Bolivia , image_flag = Bandera de Bolivia (Estado).svg , flag_alt = Horizontal tricolor (red, yellow, and green from top to bottom) with the coat of arms of Bolivia in the center , flag_alt2 = 7 × 7 square p ...

Brazil Brazil ( pt, Brasil; ), officially the Federative Republic of Brazil (Portuguese: ), is the largest country in both South America and Latin America. At and with over 217 million people, Brazil is the world's fifth-largest country by area ...

Guyana Guyana ( or ), officially the Cooperative Republic of Guyana, is a country on the northern mainland of South America. Guyana is an indigenous word which means "Land of Many Waters". The capital city is Georgetown. Guyana is bordered by the ...

Paraguay Paraguay (; ), officially the Republic of Paraguay ( es, República del Paraguay, links=no; gn, Tavakuairetã Paraguái, links=si), is a landlocked country in South America. It is bordered by Argentina to the south and southwest, Brazil to th ...

, and

Suriname Suriname (; srn, Sranankondre or ), officially the Republic of Suriname ( nl, Republiek Suriname , srn, Ripolik fu Sranan), is a country on the northeastern Atlantic coast of South America. It is bordered by the Atlantic Ocean to the north ...

and as a

vagrant Vagrancy is the condition of homelessness without regular employment or income. Vagrants (also known as bums, vagabonds, rogues, tramps or drifters) usually live in poverty and support themselves by begging, scavenging, petty theft, temporar ...

Colombia Colombia (, ; ), officially the Republic of Colombia, is a country in South America with insular regions in North America—near Nicaragua's Caribbean coast—as well as in the Pacific Ocean. The Colombian mainland is bordered by the Car ...

French Guiana French Guiana ( or ; french: link=no, Guyane ; gcr, label=French Guianese Creole, Lagwiyann ) is an overseas departments and regions of France, overseas department/region and single territorial collectivity of France on the northern Atlantic ...

, and

Venezuela Venezuela (; ), officially the Bolivarian Republic of Venezuela ( es, link=no, República Bolivariana de Venezuela), is a country on the northern coast of South America, consisting of a continental landmass and many islands and islets in th ...

.Remsen, J. V., Jr., J. I. Areta, E. Bonaccorso, S. Claramunt, A. Jaramillo, D. F. Lane, J. F. Pacheco, M. B. Robbins, F. G. Stiles, and K. J. Zimmer. Version 24 July 2022. Species Lists of Birds for South American Countries and Territories. https://www.museum.lsu.edu/~Remsen/SACCCountryLists.htm retrieved July 24, 2022

Taxonomy and systematics

Despite its English name, the rufous-thighed kite is not closely related to most other kites but to the "true" hawks. It shares its genus with the

double-toothed kite The double-toothed kite (''Harpagus bidentatus'') is a species of bird of prey in subfamily Accipitrinae, the "true" hawks, of family Accipitridae. It is found from central Mexico through Central America into much of northern and eastern South ...

(''H. bidentatus'') and is

monotypic In biology, a monotypic taxon is a taxonomic group (taxon) that contains only one immediately subordinate taxon. A monotypic species is one that does not include subspecies or smaller, infraspecific taxa. In the case of genera, the term "unispec ...

Description

The rufous-thighed kite is long with a wingspan of . The sexes are almost alike though the female is slightly larger than the male. Chestnut thighs give the species its English name. Adults have a slate gray head and upperparts. Their tail is slate gray with three paler gray bars and white tips to the feathers. Their throat is whitish with a dark streak down its center. Their breast is gray that becomes white at the undertail

coverts A covert feather or tectrix on a bird is one of a set of feathers, called coverts (or ''tectrices''), which, as the name implies, cover other feathers. The coverts help to smooth airflow over the wings and tail. Ear coverts The ear coverts are sm ...

. Their eye is red or orange, their

cere The beak, bill, or rostrum is an external anatomical structure found mostly in birds, but also in turtles, non-avian dinosaurs and a few mammals. A beak is used for eating, preening, manipulating objects, killing prey, fighting, probing for food, ...

lemon yellow, and their legs yellow to orange. Immature birds have dark brown upperparts with streaks on the side of the head; they are whitish below with some darker streaking on the breast and belly and barring on the flanks.Bierregaard, R. O., A. Bonan, J. S. Marks, and C. J. Sharpe (2020). Rufous-thighed Kite (''Harpagus diodon''), version 1.0. In Birds of the World (J. del Hoyo, A. Elliott, J. Sargatal, D. A. Christie, and E. de Juana, Editors). Cornell Lab of Ornithology, Ithaca, NY, USA. https://doi.org/10.2173/bow.rutkit1.01 retrieved December 8, 2022

Distribution and habitat

The rufous-thighed kite breeds in southern Brazil, northern Argentina, and Paraguay. In the non-breeding season it is regularly found further north in Amazonian Brazil, Bolivia, Guyana, and Suriname. The South American Classification Committee of the

American Ornithological Society The American Ornithological Society (AOS) is an ornithological organization based in the United States. The society was formed in October 2016 by the merger of the American Ornithologists' Union (AOU) and the Cooper Ornithological Society. Its m ...

(SACC) has documented records of vagrancy to French Guiana and Venezuela but has not evaluated a report from Colombia. The SACC also classes the species as hypothetical in Ecuador on the basis of an undocumented sight record. The rufous-thighed kite primarily inhabits lowland rainforest. It favors

primary forest An old-growth forestalso termed primary forest, virgin forest, late seral forest, primeval forest, or first-growth forestis a forest that has attained great age without significant disturbance, and thereby exhibits unique ecological featur ...

but can be found in

secondary forest A secondary forest (or second-growth forest) is a forest or woodland area which has re-grown after a timber harvest or clearing for agriculture, until a long enough period has passed so that the effects of the disturbance are no longer evident. ...

that has aged enough to have a closed canopy. It has been found in both dense and more open forests and even once in a forest patch within the city of

São Paulo São Paulo (, ; Portuguese for 'Saint Paul') is the most populous city in Brazil, and is the capital of the state of São Paulo, the most populous and wealthiest Brazilian state, located in the country's Southeast Region. Listed by the GaWC a ...

, Brazil.

Behavior

Migration

The rufous-thighed kite is an austral migrant, moving north from its southerly breeding areas into Amazonia. It has been observed migrating in loose flocks of up to 30 individuals. The knowledge of its migration continues to expand.

Feeding

The rufous-thighed kite hunts within the forest, usually in the middle to upper layers of the canopy. It hunts from a perch and usually seizes its prey from branches rather than in mid-air. Its diet appears to be mostly insects such as cicadas and

orthoptera Orthoptera () is an order of insects that comprises the grasshoppers, locusts, and crickets, including closely related insects, such as the bush crickets or katydids and wētā. The order is subdivided into two suborders: Caelifera – grassho ...

with lesser numbers of small lizards, birds, amphibians, and mammals. It has been observed following

army ant The name army ant (or legionary ant or ''marabunta'') is applied to over 200 ant species in different lineages. Because of their aggressive predatory foraging groups, known as "raids", a huge number of ants forage simultaneously over a limit ...

swarms and at least once a troop of monkeys to capture prey flushed by them.

Breeding

The rufous-thighed kite's breeding season is October to February, the austral late spring and summer. Its nest is a platform of small sticks placed in a tree fork or on a horizontal branch. The clutch size is one or two eggs. The incubation period is not known; fledging occurs about four weeks after hatch.

Vocalization

A fledgling and a parent on the nest gave "high-pitched 'chee' and disyllabic 'chee-weet' begging calls" when the other parent approached with prey. "Adults also give a three-note vocalization."

Status

The

IUCN The International Union for Conservation of Nature (IUCN; officially International Union for Conservation of Nature and Natural Resources) is an international organization working in the field of nature conservation and sustainable use of natu ...

has assessed the rufous-thighed kite as being of Least Concern. It has a very large range, but its population size is not known and believed to be decreasing. No immediate threats have been identified. It is a breeding

endemic Endemism is the state of a species being found in a single defined geographic location, such as an island, state, nation, country or other defined zone; organisms that are indigenous to a place are not endemic to it if they are also found elsew ...

in the

Atlantic Forest The Atlantic Forest ( pt, Mata Atlântica) is a South American forest that extends along the Atlantic coast of Brazil from Rio Grande do Norte state in the northeast to Rio Grande do Sul state in the south and inland as far as Paraguay and th ...

, a biome that has been almost completed destroyed. "Improved knowledge of its breeding range and biology suggests that this species may now be of conservation concern."

References

{{Taxonbar, from=Q787907 rufous-thighed kite Birds of Brazil rufous-thighed kite Taxonomy articles created by Polbot