Kite (bird)

In 1824, Vigors[5] proposed five divisions or stirpes of the family Falconidae: Aquilina (eagles), Accipitrina (hawks), Falconina (falcons), Buteonina (buzzards) and Milvina (kites, containing two genera Elanus and Milvus). He characterized the kites as having weaker bill and feebler talons than the buzzards, tail more or less forked, and wings longer than the tail.[5]^: 314

In Elanus, he grouped the black-winged kite (now several Elanus spp.), scissor-tailed kite (now Chelictinia), and swallow-tailed kite (now Elanoides). These species all have pointed wings with the second primary the longest. The pattern of scales on the legs (acrotarsi) is reticulated, and the toes are separated. But Vigors noted that only the black-winged kite had rounded undersides on the nails of its talons, a trait found in the osprey but not in any other raptors, and thus suggested a separation of Elanus into two sections.[5]^: 333 A year later, he established a separate genus Nauclerus for the scissor- and swallow-tailed kites.[6]

Milvus contained the familiar red and black kites. The fourth primary feather is the longest, leg scales are scutellated, and the exterior toe is united to the middle toe by a membrane.[5]^: 334

Vigors placed Ictinia – "the Milan Cresserelle of M. Vieillot" and "the Mississippi Kite of Mr. Wilson" – into Buteonina. Though noting that "the wings are of considerable length, extending far beyond the tail, a character which has induced M. Vieillot and others to place this bird near the Kites", he wrote that the strong affinity in characteristics and manners warranted it to be placed closer to the falcons.[5]^: 331

Swann's 1922 synopsis grouped all the kites together with the "cuckoo-falcons" and honey buzzards into a large Milvinæ subfamily.[7] His order was: Elanoides, Chelictinia, Milvus, Lophoictinia, Rostrhamus, Helicolestes, Chondrohierax, Odontriorchis, Gypoictinia (=Hamirostra), Elanus, Gampsonyx, Ictinia, Harpagus, Baza, Aviceda, Henicopernis, Machærhamphus, Pernis.

In contrast, Peters[8] grouped the large kites into subfamily Milvinae and most small kites into Elaninae, with a few small kites joining the honey-buzzards and bazas in Perninae. His arrangement of kite genera was as follows:

• Elaninae: Elanus, Chelictinia, Machaerhamphus.
• Perninae: Elanoïdes, (Aviceda, Henicopernis, Pernis, Odontotriorchis), Chondrohierax.
• Milvinae: Harpagus, Ictinia, Rostrhamus, Helicolestes, Milvus, Lophoictinia, Hamirostra, Haliastur.
• Polyhieracinae: Gampsonyx

The pearl kite Gampsonyx had variously been placed with the accipiters, forest-falcons, or elanine kites. It was not until the 1960s that a similar molt schedule established its affinity to Elanus.

By 2015, genetic research showed that many of the kite genera are related to honey-buzzards, and that the tiny bat hawk (Machaerhamphus or Macheirhamphus) is actually related to the huge harpy eagles. Several of the large kites are related more closely to the Buteo hawks (buzzards) than to the group of "true" kites and sea-eagles.

Boyd[9] places the "true" milvine kites (Milvus and Haliastur) with the sea-eagles in tribe Milvini within Buteoninae. This results in the following arrangement (genera in parentheses are not generally called kites):

• Elaninae: Gampsonyx, Chelictinia, Elanus.
• Perninae: Chondrohierax, Leptodon, Elanoides, (Pernis), Hamirostra, Lophoictinia, (Henicopernis).
• Buteoninae
  • Harpagini: Harpagus.
  • Milvini: Haliastur, Milvus, (Haliaeetus, Icthyophaga).
  • Buteonini: many genera, including the kites Ictinia, Rostrhamus, and Helicolestes.

    Ictinia is near-basal, after the Old-World genus Butastur. Rostrhamus and Helicolestes form a clade with the black-collared hawk (Busarellus) and the crane hawk (Geranospiza).

As early as 1882, Anton Reichenow had also placed Section Milvinæ alongside Section Buteoninæ in Subfamily Buteoninæ.[10]^: 18