# Harrier (bird)

A harrier is a member of the genus Circus in Accipitridae, a family of birds of prey. Harriers characteristically hunt by flying low over open ground, feeding on small mammals, reptiles, or birds. The young of the species are sometimes referred to as ring-tail harriers. They are distinctive with long wings, a long narrow tail, the slow and low flight over grasslands and skull peculiarities. The harriers are thought to have diversified with the expansion of grasslands and the emergence of C$_4$ grasses about 6 to 8 million years ago during the Late Miocene and Pliocene.

## Taxonomy

The genus Circus was introduced by the French naturalist Bernard Germain de Lacépède in 1799. The type species was subsequently designated as the western marsh harrier. Most harriers are placed in this genus. The word Circus comes from the Ancient Greek κρέξ (kréx) referring to a long legged bird, and is possibly ultimately derived from an onomatopoeia. The name harrier is thought to have been derived either from Harrier (dog), or by a corruption of harrower, or directly from harry.
The genera Circus has in the past been placed in the subfamily Circinae but molecular phylogenetic studies have shown that such a grouping is polyphyletic for Accipitrinae. The harrier-hawks in the genus Polyboroides are not closely related and are placed in their own subfamily Polyboroidinae

### Ring-tails

Ring-tail is an informal term used by birders for the juveniles and females of several harrier species when seen in the field and not identifiable to an exact species. Ring-tail harriers include the juveniles and females of Montagu's harrier (Circus pygargus), hen harrier (Circus cyaneus), and pallid harrier (Circus macrourus).

## Species

The genus contains 16 species:
Genus Circus – Lacépède, 1799 – sixteen species :
| Common name | Scientific name and subspecies | Range | Size and ecology | IUCN status and estimated population |
| Montagu's harrier | Circus pygargus (Linnaeus, 1758) | Eurasia, winters in Africa and India | Size: Habitat: Diet: | LC |
| Hen harrier | Circus cyaneus (Linnaeus, 1766) | Eurasia | Size: Habitat: Diet: | LC |
| Northern harrier | Circus hudsonius (Linnaeus, 1766) | North America | Size: Habitat: Diet: | LC |
| Western marsh harrier | Circus aeruginosus (Linnaeus, 1758) Two subspecies C. a. aeruginosus (Linnaeus, 1758) C. a. harterti Zedlitz, 1914 | Europe, western Asia; winter range includes Africa and India. | Size: Habitat: Diet: | LC |
| Eastern marsh harrier | Circus spilonotus Kaup, 1847 | Asia (migratory) | Size: Habitat: Diet: | LC |
| African marsh harrier | Circus ranivorus (Daudin, 1800) | southern and central Africa | Size: Habitat: Diet: | LC |
| Swamp harrier | Circus approximans (Peale, 1849) | New Zealand, Australia, Pacific islands | Size: Habitat: Diet: | LC |
| Papuan harrier | Circus spilothorax (Salvadori & D'Albertis, 1875) | New Guinea | Size: Habitat: Diet: | LC |
| Malagasy harrier | Circus macrosceles (Newton, 1863) | Indian Ocean (Madagascar and the Comoro Islands) | Size: Habitat: Diet: | EN |
| Réunion harrier | Circus maillardi J. Verreaux, 1862 | (Indian Ocean) Réunion Island | Size: Habitat: Diet: | EN |
| Long-winged harrier | Circus buffoni (Gmelin, JF, 1788) | South America | Size: Habitat: Diet: | LC |
| Spotted harrier | Circus assimilis (Jardine & Selby, 1828) | Australia, Indonesia | Size: Habitat: Diet: | LC |
| Black harrier | Circus maurus (Temminck, 1828) | southern Africa | Size: Habitat: Diet: | EN |
| Cinereous harrier | Circus cinereus Vieillot, 1816 | South America | Size: Habitat: Diet: | LC |
| Pallid harrier | Circus macrourus (S. G. Gmelin, 1770) | migratory: eastern Europe, Asia, Africa (winter) | Size: Habitat: Diet: | LC |
| Pied harrier | Circus melanoleucos (Pennant, 1769) | Asia | Size: Habitat: Diet: | LC |

### Fossils

* † Eyles's harrier, Circus eylesi (prehistoric)
* † Wood harrier, Circus dossenus (prehistoric)