Elaninae

Description

Elanus species are primarily rodent hunters, searching for prey from a perch or often hovering like kestrels. Their tail is unforked. Chelictinia feeds on the wing, taking insects from the air, or small reptiles and insects from tree branches. Its tail is very long and deeply forked, like Elanoides which has similar feeding habits but is larger.

Both Elanus and Chelictinia have similarities in markings, with red eyes, a black patch above the eye, yellow legs and cere, and black beak.

Gampsonyx is very small, also feeding on insects, with the size and coloration typical of the Asian falconets. It is black above and white below, often with a tinge of rufous around the legs.

Taxonomy and systematics

In 1851 British zoologist Edward Blyth described Elaninae, the "smooth clawed kites", as a formal subfamily of Accipitridae. However they are also grouped in Accipitrinae, the broader subfamily of hawks and eagles described by French ornithologist Louis Pierre Vieillot in 1816.

Nicholas Vigors in 1824 had grouped Elanus and "true Milvus" together into Stirps Milvina, the kites. Earlier, the terms "kite" in English or "iktinos" in Greek referred only to the red or black (milvine) kites. French ornithologists used the term "milan" for both the milvine and elanine kites.

Around the same time, in 1823, Louis-Pierre Vieillot had placed the group (in five species) together into his own genus Elanoïdes, rather than Savigny's Elanus. Vigors listed three known species: Elanus melanopterus, E. furcatus, and E. Riocourii. But he noted that the latter two had more forked tails and probably didn't have nails that were rounded underneath. The following year he gained access to specimens of the fork-tailed kites and split them from Elanus into a separate genus, Nauclerus.

In 1931, Peters used the subfamily Elaninae, listing its members as Elanus, Chelictinia, and Machaeramphus. He placed Elanoïdes in subfamily Perninae, and Gampsonyx with the forest falcons in Polyhieracinae. In the 1950s, several authors found Gampsonyx was related to Elanus rather than the falcons, based on morphological features and molt schedule.

Lerner and Mindell describe the Elaninae as: "Kites noted for having a bony shelf above the eye, Elanus is cosmopolitan, Gampsonyx is restricted to the New World and Chelictinia is found in Africa". This is in contrast to the Perninae, which are: "Kites mainly found in the tropics and specializing on insects and bee or wasp larvae, all lack the bony eye shield found in the Elaninae".

Comparisons of sequences for certain mitochondrial marker genes indicate that some elanine kites split early from the rest of the Accipitridae. Wink and Sauer-Gurth found that Elanus was less related than the osprey and secretary bird (which are often placed in a separate family), but noted that this was not strongly indicated. However, Lerner and Mindell found that the osprey was less related, but Elanus leucurus was basal to the other Accipitridae.

Negro and colleagues have discussed convergent traits between kites in the genus Elanus and owls, such as a lower acidity of the stomach and some specialized flight feathers otherwise not found in diurnal raptors.

Lerner and Mindell also found that Elanoides forficatus grouped with Perninae, such as the type species Pernis apivorus and the Australian endemics Lophoictinia and Hamirostra. Chelictinia, Machaerhamphus, and Gampsonyx were not included in these genetic sequencing studies.