About the African Harrier-Hawk | Cape Urban African Harrier-Hawk Project

Meet Polyboroides typus typus

The African Harrier-Hawk is a medium-large grey raptor with broad wings, a long tail carrying one white band, and a small head on a long neck.

Adults and young look quite different! Adults are pale ash-grey above with a finely barred black-and-white belly, yellow legs, and a patch of bare skin on the face. That bare patch gives the bird its other name. Gymnogene means something close to "naked cheek".

In the air they look loose and unhurried, drifting low along tree lines rather than circling high like a buzzard. They occur across most of sub-Saharan Africa in woodland and forest edge, and in Cape Town they are resident year-round and often spotted on buildings and in gardens.

Adult African Harrier-Hawk perched and calling, showing grey plumage, barred belly and white tail band, Bellville

Telling the ages apart

An African Harrier-Hawk takes about three years to reach full adult plumage, and the stages look different enough that they are often reported as separate species. Immatures are the more tricky ones to identify!

Adult

Around three years and older

Ash-grey head, back and wings
Belly and thighs finely barred black and white
Black tail with one broad white band
Bare yellow face that flushes pink or red on occasion
Bright yellow legs

Adult African Harrier-Hawk perched, side view, Marina da Gama

Adult African Harrier-Hawk perched, side view, Cape Town

Adult African Harrier-Hawk perched, front view, Bellville

Adult African Harrier-Hawk in flight, Plumstead

Adult African Harrier-Hawk in flight seen from above, Plumstead

Immature

Roughly one to three years

Grey coming through the brown, usually in patches
Barring on the belly started but incomplete
Tail band there but duller, sometimes extra bars
Face dull yellow, rarely flushing
Called an adult at distance, a juvenile up close

Immature African Harrier-Hawk, front view, Cape Town

Immature African Harrier-Hawk in flight, Marina da Gama

Immature African Harrier-Hawk, side view, Marina da Gama

Juvenile

First year

Variably coloured, from light buff to rufous/dark brown
Underparts streaked and untidy looking
Face dull greenish-yellow
Same small head, long neck, broad wings and loose flight
Sometimes confused as an eagle or a buzzard

Juvenile African Harrier-Hawk, pale form, perched front view

Juvenile African Harrier-Hawk, pale form, in flight

Juvenile African Harrier-Hawk perched, Marina da Gama

Juvenile African Harrier-Hawk in flight, Cape Town

Juvenile African Harrier-Hawk perched, side view

Juvenile African Harrier-Hawk, dark form, perched, Kirstenhof

Juvenile and adult African Harrier-Hawk duelling in flight

Juvenile and adult African Harrier-Hawk flying together

Contrasting the plumage of the adult and juvenile African Harrier-Hawk.

Juveniles are important to report. A young bird hanging about one area through the year usually means a pair bred somewhere close by.

What makes it unusual

Anatomy

Its legs bend both ways

The African Harrier-Hawk has one of the rarest anatomical adaptations in the raptor world! The joint that works as the bird's ankle flexes backwards as well as forwards, through about 190 to 205 degrees. Almost no other bird can do this. It exists so the bird can push a long leg into a tree hollow or a weaver nest, bend it round a corner, and hook out whatever is inside.

African Harrier-Hawk reaching a double-jointed leg into a cavity, Clovelly

Juvenile African Harrier-Hawk clambering on a palm trunk, Plumstead

Evolution

Just one other bird has arrived at the same solution

The Crane Hawk of Central and South America has an almost identical joint and the same cavity-raiding habit. The two are not closely related and are not on the same continents. Yet same answer to same problem.

Behaviour

It climbs

African Harrier-Hawks work their way along trunks, cliffs and walls using their wings for balance, hanging sideways and upside down while they feel about for prey. In the suburbs that means palm crowns, roof spaces, eaves and garden walls as much as trees.

African Harrier-Hawk clambering on a tree trunk, Kommetjie

African Harrier-Hawk clambering through a canopy, Newlands

Hunting

Its adaptable hunting techniques makes it unique using four ways of going about it

Low soaring just above the canopy is the usual method, and the one that gets it mobbed. The others are high soaring, hunting from a perch, and working through the canopy or along the ground. The Harrier-Hawk is a clever bird - it appears to read the intensity of mobbing to locate active nests, turning back when the small birds lose interest.

Face

The face changes colour

The bare skin is normally soft yellow and flushes through orange to pink or red when the bird is excited, displaying or aggravated. It is a useful cue in the field. A flushed face often means something is up.

Adult African Harrier-Hawk with the bare facial skin unflushed and yellow, Marina da Gama

Adult African Harrier-Hawk with the bare facial skin flushed orange-red

Breeding

Usually one chick survives

The female lays one to three eggs and sits for about 35 days while the male hunts. Where two hatch, the older often kills the younger. Whether the food supply in a city changes that outcome is a question we hope this study can settle.

Reputation

Every small bird in the area hates it

Because it specialises in robbing nests, it gets mobbed by weavers, bulbuls, starlings, crows and drongos. A sudden racket of alarm calls is often the first sign one is about. If you hear a racket, look up.

African Harrier-Hawk mobbed by a crow, Cape Town

African Harrier-Hawk mobbed by a gull, Plumstead

Giveaway behaviours

Plumage is not the only means to identify the African Harrier-Hawk, especially with the variability of the juvenile plumage! Habits that help identify the bird include:

In the air

Drifting slowly and low along a tree line
Long legs left dangling
Extended wings with loose, floppy wingbeats
A mixed flock of small birds going up around it

In a tree

Clambering about a trunk or through a canopy
Hanging upside down at a nest or hole
Working a palm crown or a weaver colony
Sitting quietly in the same tree

Juveniles often confused with

Black Sparrowhawk: darker, faster, direct flight
Jackal Buzzard: rufous chest, no white tail band

Report a sighting

The wider picture

The species is listed as Least Concern, and on paper its population is stable. However recent work shows that the African Harrier-Hawk is showing sharp declines outside of protected areas. Habitat converted to farmland, poisoning and persecution are the main causes.

That is what makes Cape Town interesting. A bird under pressure across much of its range appears to be holding its own, or gaining, in a city as big as Cape Town. Working out what the city offers it and how it adapts is worth doing to understand long term survival of birds such as the African Harrier-Hawk.