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Rufous-thighed Kite
Harpagus diodon

Status: Lower risk

Population Trend: Unknown.

Other Names: 

Harpagus diodon
click to enlarge
Distribution: Neotropical. Breeds from eastern BOLIVIA (Santa Cruz) through southern and eastern BRAZIL (Bahia to Rio Grande do Sul) to PARAGUAY, URUGUAY, and northern ARGENTINA (Jujuy, Salta, Misiones); non-breeding wanderers occur north to northeastern ECUADOR, the GUIANAS, and Amazonian BRAZIL. more....

Subspecies: Monotypic.

Taxonomy: This genus was originally placed in Falconidae because of the two "teeth" on the upper mandible (Sharpe 1874), but such features are not that unusual in kites and are not taxonomically significant (Miller 1937, Amadon 1961). Amadon (1961, 1964) argued that Harpagus a milvine kite, and Vesta and Stresemann (1960) found that the molt of the genus is typical of milvine kites. More recent researchers have placed the genus among the butenoines and close to Buteo, Accipiter, and Circus (Kemp and Crowe 1990, Griffiths 1994, Holdaway 1994, and Griffiths et al. 2007).

Movements: Irruptive or local migrant (Bildstein 2006). Formerly regarded as sedentary by some authorities (Bierregaard 1994, Ferguson-Lees and Christie 2001), but others (Haverschmidt 1968, Hayes et al. 1994, Olivo 2001, Bildstein 2004) suggested that it is an austral migrant in the non-breeding season in the southern portions of its range. Cabanne and Seipke (2005) reported observations of migrating groups and single Rufous-thighed Kites in Itatiaia National Park, Rio de Janeiro, Brazil (where the species is also resident). They suggested that the Serra de Mantiqueria is a topographic feature of major importance in the kite migration in southern Brazil, since it serves to funnel the birds northward through the Pararíaba do Sul River Valley to the northeast.

Habitat and Habits: Occurs in lowland forests, including fragmented and undisturbed areas, where it perches in in canopy. In French Guiana, it was found in several forest types, including coastal palm forests (Thiollay 2007), and Cabanne and Roesler (2007) recorded it in Brazil in agro-ecosystems associated with patches of native forest. Unlike the Double-toothed Kite, this species was not seen displaying over the forest or following monkey troops in French Guiana (Thiollay op cit.), although both behaviors have been reported from Brazil (Cabanne 2005, Willis and Oniki 1998). These kites are not particularly wary and were not aggressive toward humans at their nest (Cabanne and Roesler op cit.).

Food and Feeding Behavior: Feeds most on large insects, especially cicadas, but also takes a few small vertebrates, including lizards, frogs, and mice (Cabanne and Roesler 2007). The latter authors observed this species hunting from a perch, and all prey were taken from branches of the medium to high canopy, never on the ground or on the wing. They also observed one kite associated with a troop of capuchin monkeys, and Willis and Oniki (1998) reported the same behavior earlier. According to Sick (1990), it also attends cohorts of Eciton army ants. The close plumage resemblance of this species to Accipiter bicolor pileatus may be an example of protective mimicry, either by the kite or by the hawk (Alfred Russell Wallace fide Newton 1896, Amadon 1961). Willis (1976) and Seipke (2002) both concluded that this kite mimics the bird-eating Accipiter to avoid trophic competition by other insectivorous birds while following monkey troops, and it is often mobbed by small birds, even though it does not prey on them. The congeneric Double-toothed Kite (H. bidentatus) has a different plumage pattern and is seldom mobbed by small birds, although they scare them off (Willis op cit.). more....

Breeding: Cabanne and Roesler (2007) recently reported their observations on four nesting attempts of this species in as many localities in the Atlantic forest in the states of Bahia, São Paulo, and Rio de Janeiro, and all in undisturbed forests. One nest was examined, and it was a shallow cup made of dried sticks and located about 12 m high in a fork made by two branches in the upper third of a tree. It was not well hidden and was very visible to the observers. Three of the nests contained a single young, and the other held two eggs, both of which hatched. Only one adult (probably the female) attended the young, roosting or perching near it, and hunting near the nest site, coinciding with behavior reported by the congeneric Double-toothed Kite (Schulze et al. 2000). The other adult delivered food to the attending adult, and the latter fed it to the nestlings. Two other 2-egg clutches of this species were reported by von Ihering (1900) and Wolfe (1938), indicating that the clutch size of this species is 1 or 2 eggs. more....

Conservation: Poorly known, but apparently uncommon to fairly common or even abundant in different portions of its range. It is apparently rare in northern South America, and the individuals found there (e.g., Venezuela) may be migrants from farther south. Ridgely and Greenfield (2001) concluded that two separate individuals recorded from the Limoncocha area of eastern Ecuador were probable vagrants, rather than austral migrants, and it appears unlikely that the species occurs there regularly. Categorized as a species of Least Concern by BirdLife International (2007). more....

Important References: 
Amadon, D. 1961. Relationships of the falconiform genus Harpagus Condor
Amadon, D. 1964. Taxonomic notes on birds of prey. American Museum
  Novitates no. 2166.
Azevedo, M.A.G., V. d.W. Piacentini, I.R. Ghizoni, Jr., J.L.B.
  Albuquerque, E.S. Silva, C.M. Joenck, A. de Mendonça-Lima, and F. Zilio.

  2006. [Biology of the Rufous-thighed Kite, Harpagus diodon, in Santa
  Catarina State, southern Brazil]. Revista Brasileira de Ornitologia
  14:351-357. (In Portuguese with English summary)
Bierregaard, R.O. 1994. Rufous-thighed Kite. Pp. 117 in del Hoyo, J., A.
  Elliott, and J. Sargatal (eds). Handbook of birds of the world. Vol. 2. New
  World vultures to guineafowl. Lynx Edicions, Barcelona, Spain.
Cabanne, G.S., and I. Roesler. 2007. A description of a nest and nestlings
  of the Rufous-thighed Kite (Harpagus diodon), with additional comments on
  diet and behavior. Ornitologia Neotropical 18:469-476.
Cabanne, G.S., and S.H. Seipke. 2005. Migration of the Rufous-thighed Kite
  (Harpagus diodon) in southeastern Brazil. Ornitologia Neotropical
Ferguson-Lees, J., and D.A. Christie. 2001. Raptors of the world. Houghton
  Mifflin, Boston, MA.
Seipke, S.H. 2002. (Abstract) Harpagus, Accipiter, and platyrrhine
  monkeys: an ecological context that favored mimicry. Conferencia sobre Aves
  Rapaces Neotropicales y Simposio del Águila Arpia. Fondo Peregrino-Panama,
  Panama City.
Sick, H. 1993. Birds in Brazil: a natural history. Princeton University
  Press, Princeton, NJ.
von Ihering, H. 1900. Catalogo-critico-comparativo dos ninhos e ovos das
  aves do Brasil. Revista Museu Paulista 4:191-300.
Willis, E.O. 1976. A possible reason for mimicry of a bird-eating hawk by
  an insect-eating kite. Auk 93:841-842.
Willis, E., and Y. Oniki. 2002. Birds of Santa Teresa, Espiritu Santo,
  Brazil: do humans add or subtract species? Papeis Avulsos de Zoologia
Wolfe, L.R. 1938. Eggs of the Falconiformes. Oologists' Record 18:2-10.

Sites of Interest:
Rufous-thighed Kite photos.
Aves de Rapina do Brasil
Species account with emphasis on Brazil.

Azevedo, Marcos Antônio Guimarães
Cabanne, Gustavo Sebastian

Last modified: 12/8/2009

Recommended Citation: Global Raptor Information Network. 2022. Species account: Rufous-thighed Kite Harpagus diodon. Downloaded from http://www.globalraptors.org on 23 Jan. 2022

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