[order] ACCIPITRIFORMES | [family] Accipitridae | [latin] Circus ranivorus | [authority] Daudin, 1800 | [UK] African Marsh Harrier | [FR] Busard grenouillard | [DE] Froschweihe | [ES] Aguilucho Lagunero Etiopico | [NL] Afrikaanse Bruine Kiekendief
The genus Circus is a cosmopolitan genus of about ten species. They are medium-sized, slender hawks, the female being considerably larger than the male. They are characterised by long, narrow, rounded tails, small beaks and long, slender legs. The most notable characteristic is the owl-like ruff of facial feathers that cover unusually large ear openings – an adaptation not for low-light hunting, but to locate prey by their rustling and squeaking in tall grasses.
The adult is 44 to 49 cm long and is mostly brown with pale streaking on the head, breast and forewing and rufous on the thighs and belly. Males and females are similar, unlike most harriers. The juvenile is dark brown with a pale breastband and pale markings on the head. The tail and flight feathers have dark barring at all ages. It is usually silent but has a high-pitched, two-note display call.
Africa : East, South
Confined mainly to wetlands, but also forages in adjacent open grasslands, agricultural lands, and even open woodland. Almost entirely absent from areas with less than 300 mm of rainfall, reflecting its preference for wetland habitats. Small wet spots of 1-2 ha in extent may be used for foraging, but larger wetlands are required for breeding. Most often seen coursing low over the ground like other harriers. Seen mostly in pairs or singly, but may roost in flocks of 10 or more.
Breeding may occur any time of year, but is mostly from June-December in southern Africa, regardless of rainfall regime. The nest is a platform of vegetation, usually placed in a reedbed above water level in a marsh, but sometimes in short sedge areas and fynbos vegetation. Clutch size is 3-6 eggs (usually 3, but occasionally 4), which are white and usually unmarked. The incubation period is 31-34 days, and the nestling period is 38-41 days. Incubation begins with the first egg, leading to a size disparity among the nestlings that often results in the starvation of the youngest chick.
Feeds mainly on small rodents (70% of diet), but birds (mostly small species, but occasionally as large as ducks), frogs, and insects are also taken. Prey is captured after a sharp, twisting descent to the ground or after an aerial chase. May also take carrion, including dead fish, and is known to raid mixed heron and egret colonies and weaver nests to eat eggs and chicks
Video African Marsh Harrier
copyright: J. del Hoyo
This species has an extremely large range, and hence does not approach the thresholds for Vulnerable under the range size criterion (Extent of Occurrence <20,000 km2 combined with a declining or fluctuating range size, habitat extent/quality, or population size and a small number of locations or severe fragmentation). Despite the fact that the population trend appears to be decreasing, the decline is not believed to be sufficiently rapid to approach the thresholds for Vulnerable under the population trend criterion (>30% decline over ten years or three generations). The population size has not been quantified, but it is not believed to approach the thresholds for Vulnerable under the population size criterion (<10,000 mature individuals with a continuing decline estimated to be >10% in ten years or three generations, or with a specified population structure). For these reasons the species is evaluated as Least Concern.
Patchily distributed and declining in many portions of its range in West and southern Africa where wetlands are being destroyed. Categorized globally as a species of “Least Concern” by BirdLife International, but it may prove to be much rarer in most of its range.
Partial migrant, somewhat nomadic, as birds seek appropriate wet habitat. Individuals can forage up to 200 km/day during the breeding season. A ringed bird that had moved 1,000 km within its first year. Appears to be sedentary in the Kampala, Uganda area.