African goshawk

The African goshawk (Aerospiza tachiro) is a medium-sized raptor endemic to sub-Saharan Africa, distinguished by its slate-grey upperparts, pale underparts with fine rufous barring, yellow eyes and cere, and long rounded tail, with adults typically measuring 35–42 cm in length, having a wingspan of about 60–70 cm, and weighing 230–510 g (females larger than males).^[1]^[2] This species, the most common and widespread accipiter on the continent, occupies a broad range across 19 countries from Senegal and Eritrea in the north to South Africa in the south, primarily in subtropical and tropical moist lowland and montane forests, but also in secondary woodlands, plantations, rural gardens, and riverine vegetation up to 3,000 m elevation.^[3]^[2] As a resident non-migratory bird, it maintains territories year-round and is often detected by its piercing calls and acrobatic display flights above the canopy.^[1]^[4] The African goshawk forages ambush-style in the forest understory or edges, capturing a diverse diet that includes small birds (such as hornbills and francolins), mammals (rodents, squirrels, bats), reptiles (lizards, snakes, chameleons), amphibians (frogs), insects, and notably freshwater crabs, with prey size varying by sex—males targeting smaller items and females larger ones.^[1]^[2] Breeding occurs in monogamous pairs that construct stick nests high in tree canopies, laying 2–3 eggs during variable seasons depending on region (e.g., September–December in southern Africa), with the female incubating while the male provides food; fledglings remain dependent for several weeks.^[2]^[1] Taxonomically placed in the family Accipitridae, the species comprises three subspecies across its range, with variations in size and plumage intensity (e.g., darker forms in humid forests); it was formerly lumped with the Red-chested Goshawk (Accipiter toussenelii) but is now recognized as distinct.^[3]^[4] Although classified as Least Concern globally due to its large extent of occurrence (over 8.9 million km²) and adaptability, populations are suspected to be declining at a rate of 1–19% over three generations owing to ongoing deforestation and habitat fragmentation.^[2]^[3]

Taxonomy and etymology

Classification

The African goshawk (Aerospiza tachiro) belongs to the kingdom Animalia, phylum Chordata, class Aves, order Accipitriformes, family Accipitridae, genus Aerospiza, and species A. tachiro.^[5] This placement reflects its position as a medium-sized bird of prey within the diverse Accipitridae family, which encompasses hawks, eagles, and Old World vultures.^[6] The species was first described in 1800 by French zoologist François Marie Daudin as Falco tachiro, based on a specimen from the collection of François Levaillant collected in Knysna, South Africa.^[5]^[7] It was subsequently classified within the genus Accipiter for over two centuries, a broad assemblage of true hawks and sparrowhawks.^[5] However, molecular phylogenetic analyses using ultraconserved elements revealed the non-monophyly of Accipiter, prompting its reclassification in 2024 to the resurrected genus Aerospiza.^[6]^[8] This change was driven by evidence of a well-supported clade comprising the African goshawk and the Chestnut-flanked sparrowhawk (Aerospiza castanotis), distinct from the core Accipiter lineage.^[5] Phylogenetically, Aerospiza tachiro forms a sister species to A. castanotis within the genus, and this pair constitutes a clade sister to Tachyspiza, a genus encompassing several other African and Asian sparrowhawks such as the Little sparrowhawk (Tachyspiza minullus).^[5] This arrangement highlights the evolutionary divergence of African-endemic sparrowhawk-like raptors, supported by genomic data that resolve relationships across the Accipitrinae subfamily. The genus name Aerospiza derives from the Greek aēr (air) and spiza (finch), evoking "air-finch" or sparrowhawk to denote its agile, finch-like aerial prowess in forested habitats; it was originally proposed by Austin Roberts in 1922 but resurrected in 2024.^[5]^[6] The specific epithet tachiro stems from Levaillant's French vernacular "Tachirond," combining tache (spot) and rond (round) to describe the bird's rounded spotting pattern.^[5]

Subspecies

The African goshawk (Aerospiza tachiro) comprises nine recognized subspecies, distinguished primarily by variations in size, plumage patterns, and coloration intensity that reflect regional adaptations across sub-Saharan Africa.^[5] These include the nominate A. t. tachiro (southern Africa, from south Angola to Mozambique and South Africa); A. t. sparsimfasciata (eastern Africa, from Somalia to Angola, Zambia, and Mozambique); A. t. unduliventer (highlands of Eritrea and Ethiopia); A. t. croizati (southwestern Ethiopia); A. t. pembaensis (Pemba Island off Tanzania); A. t. macroscelides (west Africa, from Senegal and Gambia to west Cameroon); A. t. lopezi (Bioko Island in the Gulf of Guinea); A. t. toussenelii (central Africa, from south Cameroon to north and west DR Congo); and A. t. canescens (east DR Congo to west Uganda).^[3] Morphological differences among these subspecies are subtle but notable, particularly in plumage barring and overall tone. For instance, A. t. sparsimfasciata exhibits sparser barring on the underparts compared to the denser patterns in A. t. tachiro, while west African forms like A. t. macroscelides show reduced coloration intensity and finer spotting on the throat and breast. Size variations also occur, with central and eastern subspecies tending to be slightly larger than western ones, though sexual dimorphism remains pronounced across all, with females averaging 15-20% larger than males in wing length and weight. These traits aid in camouflage within diverse forest and woodland habitats but do not warrant further taxonomic splits within the tachiro group. Taxonomic debates have centered on the relationship with the red-chested goshawk (A. toussenelii), formerly considered conspecific with A. tachiro due to overlapping ranges and superficial similarities in size and habitat use. However, vocal differences—such as distinct advertising calls—and genetic analyses indicating separate clades have led to their recognition as distinct species since the early 2000s, with A. toussenelii encompassing former subspecies like toussenelii and canescens. Ongoing proposals, as of 2024, include further splitting of subspecies such as unduliventer based on genetic divergence.^[9]^[5]

Physical description

Plumage and morphology

The African goshawk (Accipiter tachiro) is a medium-sized raptor characterized by broad wings, a long rounded tail, a short broad bill topped with a cere, and strong yellow legs equipped with long toes and sharp talons adapted for grasping prey.^[10] Its wingspan measures 55–80 cm, with overall body length ranging from 35–48 cm.^[10] Like other accipiters, it exhibits pronounced sexual size dimorphism, with females typically 20–30% larger than males; males measure 33–38 cm in length and weigh 145–248 g, while females reach 38–46 cm and 227–510 g.^[10]^[11] Adult plumage is sexually dimorphic in tone and pattern. Males display dark slate-gray upperparts, rufous underparts with fine gray barring, white undertail coverts, and prominent white tail patches; their eyes, cere, and legs are yellow.^[10] Females have lead-gray to brownish-gray upperparts, white underparts with brown barring and variable rufous tones on the breast and flanks, lacking the male's tail patches, and similarly yellow eyes, cere, and legs.^[10] Juveniles differ markedly from adults, featuring brown upperparts with white spotting and pale rufous edges to the feathers, streaked or spotted underparts in buffish white with dark brown markings, and a barred tail; this plumage transitions gradually to the adult form over 1–2 years through successive molts.^[10] Subspecies exhibit clinal variations in size, rufous intensity, and barring extent, such as deeper rufous underparts in A. t. lopezi of Bioko Island compared to the paler, more barred forms like A. t. sparsimfasciatus in East Africa.^[5]^[12]

Vocalizations

The African goshawk's primary vocalization is a short, sharp "kwit" or harsher "krit" call, delivered every 1.5–3 seconds and lasting approximately 0.05 seconds, with a pitch ranging from 1.5–2.5 kHz accompanied by harmonics; this sound is often described as a rapid clicking reminiscent of stones being struck together or a sharp "chwik."^[13]^[14]^[15] This call serves as the most common utterance, frequently used in alarm situations, pair contact, and territory advertisement.^[13] In courtship and territorial contexts, the "kwit" call is prominently featured during aerial displays, where the bird soars high while emitting the notes at dawn or in circling flights, sometimes with a second individual responding from a perch or in flight.^[13]^[15] Females produce distinct mewing notes, such as "keeeuuu," "wee wee," or "weeee-oh," which are higher-pitched and more musical than the male's calls, often heard near nests during breeding; these may accelerate in pace when the female is agitated.^[13] Softer "tchuck" or "krit" sounds can also occur from males delivering food to the nest.^[13] Juvenile African goshawks emit continuous mewing calls like "wee-eeeuw" prior to fledging, along with begging chirps and distress squeals that differ markedly from adult vocalizations in tone and persistence.^[13] Acoustic variations exist across the species' range, with minor differences in the tempo, pitch, or quality of the "kwit" note observed among subspecies or regions, such as in Congo, South Africa, and Ivory Coast populations, though the call remains generally consistent overall.^[13]

Distribution and habitat

Geographic range

The African goshawk (Accipiter tachiro) is widely distributed across sub-Saharan Africa, with its range extending from southern Senegal and Gambia in the west to Eritrea, Ethiopia and Somalia in the east, and southward to the Western Cape Province in South Africa. This distribution encompasses a broad swath of the continent, including lowlands in West and Central Africa as well as East and southern regions, and incorporates offshore islands such as Bioko in the Gulf of Guinea, and Mafia, Unguja, and Pemba off the coast of Tanzania.^[16]^[3]^[17] Several subspecies exhibit distinct geographic ranges within this overall distribution. For instance, A. t. macroscelides is found in West Africa, from Senegal and Gambia to western Cameroon, while A. t. tachiro occupies southern Africa, ranging from Angola through Zambia and Zimbabwe to South Africa. In eastern Africa, A. t. sparsimfasciatus occurs from Somalia and Kenya southward to Mozambique. Other subspecies, such as A. t. lopezi on Bioko and A. t. pembaensis on Pemba Island, are more localized to specific islands.^[17] The species occupies elevations from sea level up to 3,000 m, particularly in montane forests. No major range contractions have been documented historically, though local extirpations are likely in areas of heavy deforestation.^[3]^[18]

Habitat preferences

The African goshawk primarily inhabits dense forest environments across sub-Saharan Africa, including primary lowland tropical evergreen rainforests, secondary forests, and gallery forests along watercourses.^[19] It also occupies a variety of woodlands, such as deciduous and riverine types, as well as exotic plantations like eucalyptus stands and even wooded areas near human settlements, such as thickets adjacent to towns or rural gardens.^[19]^[3] This species demonstrates considerable adaptability to differing climatic conditions, thriving in both moist equatorial forests of West and Central Africa and drier miombo woodlands in eastern and southern regions, though it generally avoids open savannas and prefers areas with woodland edges or mangroves in coastal zones.^[19]^[1] Its presence extends from sea level to montane elevations, recorded up to 3,300 m in Ethiopia and commonly to 3,000 m in Kenya.^[19]^[3] Microhabitat requirements emphasize structural complexity for ambush predation and reproduction, with the bird favoring tall trees for perching and nesting in dense foliage or epiphytes, often in canopy cover that provides concealment; it is frequently observed or captured in low undergrowth below 3 m but relies on elevated perches in evergreen trees for roosting and hunting vantage points.^[19]^[1] Nests are typically constructed in such vegetated canopies, underscoring the need for mature forest elements even in modified landscapes like plantations.^[19]

Ecology and behavior

Diet and foraging

The African goshawk (Accipiter tachiro) is primarily an opportunistic predator with a diet dominated by birds, which constitute approximately 66% of prey items by number in East African populations, followed by small mammals at around 30%. Avian prey includes small passerines such as greenbuls and sunbirds, as well as larger species up to the size of hornbills, francolins, or green-pigeons, often targeting nestlings or individuals in mixed-species flocks. Mammals in the diet typically comprise rodents like rats and mole-rats, squirrels, and bats, while reptiles such as lizards and chameleons, amphibians including frogs and toads, insects like beetles and antlions, and even crabs supplement the intake.^[1] Regional variations occur; for instance, stomach content analyses from 43 individuals in the Democratic Republic of Congo show lizards as the predominant prey, whereas in Ivory Coast (n=10), frogs and lizards account for 50% of the diet. Prey size generally does not exceed 600 g, though larger items like Latham's francolin have been recorded. As an ambush hunter adapted to forested environments, the African goshawk employs still-hunting techniques, perching motionless in canopy cover or the forest understory to observe potential prey before launching short, explosive glides or low-level flights to surprise targets. It may also stoop from elevated positions during occasional soaring flights or engage in agile sub-canopy pursuits, using its strong talons to capture and subdue victims.^[1] This species is particularly attracted to mixed-species bird flocks, where it exploits the distraction of foraging groups to strike. Foraging occurs mainly solitarily or in loose pairs, with daily activity peaking during crepuscular periods at dawn and dusk under low light conditions, when prey is more active and visibility aids surprise attacks; the bird remains largely inactive during midday heat. Prey is typically swallowed whole if small or torn into pieces if larger, and foraging bouts often concentrate near water sources or woodland edges where prey density is higher.^[1] Territorial defense may occasionally interrupt foraging, with individuals vocalizing to ward off intruders in prime hunting areas.

Breeding and reproduction

The breeding season of the African goshawk (Accipiter tachiro) varies by region, occurring year-round in equatorial areas such as Kenya with peaks from March to July and October to February, while in southern Africa it typically spans September to February, mainly in October.^[20] Laying dates include August and October in Sierra Leone, June and July in The Gambia, October and November in Gabon, and January to February or September in Ghana.^[20] Pairs may produce a second brood within 2–3 months of fledging or following clutch failure.^[20] Nests are built by both sexes as platforms of dry sticks, measuring 40–70 cm in diameter and 8–30 cm deep with walls 20–45 cm thick, lined with green leaves and lichen for camouflage.^[1] They are typically placed 4–20 m high (often 8–10 m) in well-wooded areas or plantations, concealed in dense foliage, and pairs usually construct a new nest annually, sometimes 20–50 m from old ones or reusing prior structures.^[20] The clutch comprises 1–3 eggs (usually 2, with a mean of 2.4 in some populations), laid at 3-day intervals; eggs measure approximately 42–48 mm by 35–39 mm, weigh about 34 g, and are bluish or greenish white, occasionally marked with brown or lilac spots.^[20]^[21] Incubation begins with the first egg and lasts 28–37 days, performed solely by the female, who is provisioned with food by the male and leaves the nest only twice daily for short periods.^[20]^[21] Chicks hatch altricially at 2–4 day intervals, with initial feathers appearing by 14 days and becoming fully feathered by around 20 days (except the head); they begin self-feeding at about 28 days but rely on the female for brooding and prey delivery, with the male continuing to supply food.^[20] Fledging occurs at 32–42 days (typically 35 days), after which young remain near the nest for up to 2 months, dependent on parents for 60–70 days total and learning hunting skills during this period.^[1]^[21] Siblicide is rare, though one egg may fail to hatch due to infertility, and breeding attempts often result in 1–2 fledglings; nests face predation risks from larger raptors, including the black sparrowhawk (Accipiter melanoleucus).^[20]^[22] The African goshawk (Accipiter tachiro) exhibits a predominantly solitary lifestyle outside of the breeding season, with individuals or monogamous pairs occupying and defending exclusive territories year-round. Unlike some raptors that form communal roosts or flocks, this species does not aggregate in large groups, maintaining loose associations at most within family units shortly after fledging, though juveniles typically disperse soon thereafter. Territorial defense is a core aspect of its behavior, with pairs actively patrolling and protecting home ranges that vary in size depending on habitat density and prey availability; radio-tracking studies in southern African woodlands have documented individual winter home ranges of at least 28 hectares (0.28 km²), while pair territories in East African forests may extend to 1.5–2 square miles (approximately 3.9–5.2 km²). Defense intensifies during the breeding period but persists throughout the year, often involving vocalizations and aerial pursuits to repel intruders.^[23]^[1] Display behaviors play a key role in territorial maintenance and pair bonding, featuring high-altitude flights where pairs circle or soar above the forest canopy, particularly in the early morning or evening. These displays incorporate slow, exaggerated wing-beats interspersed with gliding descents and occasional steep dives toward the treetops, sometimes accompanied by fluffed undertail coverts for visual emphasis; such sky-dancing persists year-round, signaling occupancy to rivals. Interactions with conspecifics and other species are typically aggressive, with territorial pairs chasing away intruding raptors or potential threats such as monkeys through rapid aerial pursuits and vocal threats. While primarily solitary foragers, African goshawks occasionally engage in opportunistic kleptoparasitism, attempting to steal prey from smaller accipiters, though this is infrequent and context-dependent.^[1]

Conservation

Status and population

The African goshawk (Accipiter tachiro) is classified as Least Concern on the IUCN Red List, based on the 2024 assessment by BirdLife International.^[3] This status reflects its widespread distribution across sub-Saharan Africa and the absence of threats severe enough to qualify it for a higher risk category, though the overall population trend is decreasing at a rate not approaching the thresholds for Vulnerable.^[3] The global population size has not been quantified, but it exceeds 10,000 mature individuals and is considered the most common African Accipiter species.^[3] Local density estimates vary by habitat and region, ranging from approximately 0.3 pairs per km² (or 30 pairs per 100 km²) on the Nyika Plateau in Malawi to 1 pair per km² (or 100 pairs per 100 km²) in eastern Liberia's forests.^[18] These figures indicate relatively high densities in suitable forested areas, supporting the species' Least Concern designation despite no comprehensive total estimate. Population trends show no rapid global decline, but a 12.8% loss of tree cover within the species' range over the past three generations (from 2001–2023) suggests ongoing pressures, particularly in localized areas.^[3] Monitoring is limited, with no dedicated systematic programs; data derive primarily from ad hoc raptor surveys and forest inventories rather than long-term tracking.^[3]^[18] Research gaps persist, including insufficient data on subspecies populations—such as A. t. macroscelides and A. t. unduliventer—and a lack of robust global trend assessments. Recent systematic studies have clarified plumage variation and subspecies boundaries but have not directly addressed population stability through genetics.^[5]

Threats and conservation measures

The African goshawk faces several anthropogenic threats, primarily habitat loss due to deforestation and conversion of forests to agricultural land, which has led to a suspected population decline of 1-19% over three generations. Tree cover within its range has declined by 12.8% over the same period, with the species showing a medium dependency on forest habitats, particularly in regions like west and central Africa where logging and agricultural expansion are intense. Additionally, the bird is frequently shot by hunters and villagers in areas such as the Democratic Republic of Congo, where it is perceived as a threat to poultry. Poisoning poses another risk, with high levels of DDT detected in samples from the Zambezi Valley in Zambia, though its impact as a major threat remains unconfirmed; broader raptor poisoning from rodenticides and other pesticides affects African birds of prey indirectly. The species also appears in trade datasets with high prevalence in three of seven monitored sources, indicating potential illegal capture for falconry or other uses. Conservation measures for the African goshawk are not species-specific but benefit from broader forest protection efforts across its range. It is protected within numerous conservation sites, including national parks such as Kruger National Park in South Africa and Virunga National Park in the Democratic Republic of Congo, where large forest tracts provide suitable habitat. International trade is regulated under CITES Appendix II, subjecting it to export controls to prevent overexploitation. Organizations like the Peregrine Fund support raptor conservation in regions such as Kenya through habitat protection, anti-poaching initiatives, and efforts to curb poisoning practices, which indirectly aid the species via the Global Raptor Impact Network. Recommendations emphasize strengthening anti-poaching enforcement, establishing habitat corridors to mitigate fragmentation, and monitoring trade to address emerging pressures. Overall, while currently classified as Least Concern with a decreasing but stable population trend, accelerated deforestation could elevate the African goshawk to Vulnerable status, underscoring the need for sustained forest conservation to maintain its widespread but forest-dependent populations.