Secretarybird Sagittarius serpentarius Scientific name definitions

The Secretarybird is an iconic member of sub-Saharan savanna habitats. Secretarybirds are unmistakable and elegant, with long legs, long central tail feathers, and mostly gray plumage accented with black wings and thighs. Named for their elongated head plumes, which resemble writing quills, Secretarybirds stride through the savanna, hunting for a wide variety of prey items, including insects, small vertebrates, and perhaps most famously, snakes. When prey is located, they subdue it with swift kicks from their feet, which have relatively short toes. They are a mostly solitary species, although sometimes pairs will forage close to each other. While Secretarybirds are mostly sedentary, they can be nomadic at times, following changes in rainfall, grazing conditions, and fires.

125–150 cm; c. 2300–4270 g; wingspan 191–215 cm (1 Ferguson-Lees, J., and D. A. Christie (2001). Raptors of the World. Christopher Helm, London, UK. Close ). Unmistakable , terrestrial raptor , with long pink legs, long black crest feathers, bare orange face , hooked aquiline bill and long central tail feathers . Grey above, white below with black flight feathers , abdomen and thighs. Female is probably slightly smaller and less bluish than male (1 Ferguson-Lees, J., and D. A. Christie (2001). Raptors of the World. Christopher Helm, London, UK. Close ). Juvenile is similar to adult, but has shorter tail and crest (1 Ferguson-Lees, J., and D. A. Christie (2001). Raptors of the World. Christopher Helm, London, UK. Close ), with grey barring on white underwing-coverts and undertail-coverts; also paler face; brown edges to grey dorsal feathers, especially in juvenile female. Eye changes from grey to brown and bill from black to blue-grey when adult. Confusion with other raptors impossible, but at long range or in brief view might be momentarily mistaken for a bustard or crane, especially Blue Crane (Anthropoides paradiseus) (1 Ferguson-Lees, J., and D. A. Christie (2001). Raptors of the World. Christopher Helm, London, UK. Close ).

Senegambia E to Eritrea and Somalia, and S to South Africa.

Steppe or tree and grass savanna, favouring short grass with scattered acacia (Acacia) thorn trees to provide sites for roosting and nesting, but found also in large-scale cereal farmland and subdesert areas (1 Ferguson-Lees, J., and D. A. Christie (2001). Raptors of the World. Christopher Helm, London, UK. Close ). Rarely, visits clearings in woodland or forest. Recorded from sea-level (1 Ferguson-Lees, J., and D. A. Christie (2001). Raptors of the World. Christopher Helm, London, UK. Close ) to 3150 m (2 Ash, J. S., and J. Atkins (2009). Birds of Ethiopia and Eritrea: An Atlas of Distribution. Christopher Helm, London, UK. Close ).

Sedentary (with regular seasonal breeding) in some areas, but nomadic in most areas in response to changes in rainfall, grazing and fires. Adult males usually last to forsake territories; juveniles wander widely in search of places unoccupied by mated pairs. May enter and breed regularly in an area for several years and then be absent, or present only in much-reduced numbers.

Mostly arthropods, especially grasshoppers (Orthoptera) and beetles (Coleoptera), but devours most small animals, including frogs, lizards, small tortoises, snakes  (including venomous species) (1 Ferguson-Lees, J., and D. A. Christie (2001). Raptors of the World. Christopher Helm, London, UK. Close ), domestic chickens and other birds (1 Ferguson-Lees, J., and D. A. Christie (2001). Raptors of the World. Christopher Helm, London, UK. Close ), including migrant Marsh Warblers (Acrocephalus palustris) (3 Åkesson, S. (1991). Secretary Bird Sagittarius serpentarius feeding on Marsh Warblers Acrocephalus palustris in Tsavo, Kenya. Scopus. 15: 46-47. Close ), as well as small rodents, hedgehogs, mongooses, squirrels, hares and even freshwater crabs (1 Ferguson-Lees, J., and D. A. Christie (2001). Raptors of the World. Christopher Helm, London, UK. Close ); eggs and young of birds also taken. Crop and stomach of a salvaged adult female contained 13 grasshoppers and eight snakes (4 Davies, G.P.D., Retief, E.F. and Smit-Robinson, H. (2014). Snakes in the diet of Secretarybirds Sagittarius serpentarius: an example from Balfour, Mpumalanga. Ornithological Observations. 5: 361-364. Close ). Usually kills prey by fast kicks with the long legs and stout toes ; swallows it whole (has wide gape), and tears only larger prey while holding it down with the inner toes. Seizes snakes with bill and drops them from high in the air; stamps on other mobile or dangerous prey by using stubby toes (1 Ferguson-Lees, J., and D. A. Christie (2001). Raptors of the World. Christopher Helm, London, UK. Close ). Sometimes caches prey under bush (1 Ferguson-Lees, J., and D. A. Christie (2001). Raptors of the World. Christopher Helm, London, UK. Close ). Usually hunts alone or with mate in close proximity. Regularly hunts around grass fires, taking dead prey, but shuns large carrion (1 Ferguson-Lees, J., and D. A. Christie (2001). Raptors of the World. Christopher Helm, London, UK. Close ).

Secretarybird is a silent bird, and one will rarely hear any vocalization when birds are seen feeding. In several situations of excitement however, it utters loud roaring calls which sound quite surprising.

Vocal Development

Small chicks beg with soft cheeping calls. As the birds become older, calls evolve into insisting clucking, mewing, squealing, and eventually braying notes (5 Kemp, A.C. (1994). Family Sigittariidae (Secretarybird). In: del Hoyo, J., Elliott , A., Sargatal, J. Eds. Handbook of the Birds of the World. Vol. 2 Lynx Edicions, Barcelona. Close ). Braying calls are similar to adult's Croak call, but more stuttering and slightly higher-pitched. They are also used by older chicks to threaten intruders. Young in the nest may also call at night.

Vocal Array

Croak. A very low-pitched guttural croak or roaring groan urrrrrrh repeated several times (reminiscent of a mammal or e.g. a cormorant). Duration of croak ⁓0.7-1.5s.

Kee-uk. A repeated kee-uk...kee-uk...kee-uk sounding like a gull-like nasal laughter (recording in 6 Newman, D. (2013). 500 Common Bird Calls in Southern Africa. Struik Nature, Cape Town, South Africa. Close ). Presumably the same vocalization is also described as a rapid ou-ook..ou-ook (7 van Someren, V. G. L. (1956). Days with birds: studies of habits of some East African species. Fieldiana Zoology 38:1–520. Close ) or fast, high-pitched ko-ko-ko-ko-ka or louder kowaaaaa (8 Ferguson-Lees, J., and D. A. Christie (2001). Raptors of the World. Princeton University Press, Princeton, NJ, USA. Close ).

Other. A full-throated oo-or-kok is said to be a usual call (7 van Someren, V. G. L. (1956). Days with birds: studies of habits of some East African species. Fieldiana Zoology 38:1–520. Close ). Softer clucking calls and low whistles are given by the mates on the nest (5 Kemp, A.C. (1994). Family Sigittariidae (Secretarybird). In: del Hoyo, J., Elliott , A., Sargatal, J. Eds. Handbook of the Birds of the World. Vol. 2 Lynx Edicions, Barcelona. Close ). Mewing cries are said to be given when roosting at night (9 Brown, L. H., E. K. Urban, and K. Newman (1982). The Birds of Africa. Volume 1. Academic Press, London, UK and New York, USA. Close ).

Geographic Variation

None documented.

Phenology

Croak calls may be uttered occasionally all year, but at the onset of the breeding period, an increase in calling while soaring high above the nest area can be noted (5 Kemp, A.C. (1994). Family Sigittariidae (Secretarybird). In: del Hoyo, J., Elliott , A., Sargatal, J. Eds. Handbook of the Birds of the World. Vol. 2 Lynx Edicions, Barcelona. Close ). Equally so, one or both members of a pair may perform pendulum display flights while calling.

Daily Pattern of Vocalizing

There is no clear daily pattern of vocalizing, and vocal activity is mainly determined by the events during the day, such as alarming for intruders or breeding activities.

Places of Vocalizing

Croak calls are uttered either on the ground, in flight, or on the nest in the canopy of a tree (very often a dense flat-topped acacia).

Sex Differences

No differences have been documented between males and females.

Social Content and Presumed Functions of Vocalizations

The Croak call is the main call, uttered in a variety of situations. It is uttered in flight during pendulum displays above its territory, at the nest by mates during a bowing greeting display, and on the ground during fights among rivaling birds or when signaling danger. A single croak indicts alarm, while deeper louder croaks are used in threat (5 Kemp, A.C. (1994). Family Sigittariidae (Secretarybird). In: del Hoyo, J., Elliott , A., Sargatal, J. Eds. Handbook of the Birds of the World. Vol. 2 Lynx Edicions, Barcelona. Close ). The kee-uk call has been noted on the nest (6 Newman, D. (2013). 500 Common Bird Calls in Southern Africa. Struik Nature, Cape Town, South Africa. Close ). It is not entirely clear if the kee-uk call is exclusively an adult vocalization used in alarm or contact (6 Newman, D. (2013). 500 Common Bird Calls in Southern Africa. Struik Nature, Cape Town, South Africa. Close ), a call uttered in surprise or fear (7 van Someren, V. G. L. (1956). Days with birds: studies of habits of some East African species. Fieldiana Zoology 38:1–520. Close ), or also uttered by chicks said to make 'a sharp sound heard as chee-uk-chee-uk-chee-uk for their first 30 days' (9 Brown, L. H., E. K. Urban, and K. Newman (1982). The Birds of Africa. Volume 1. Academic Press, London, UK and New York, USA. Close ).

During territorial disputes, encounters frequently involve, leaping and kicking with wings or legs, making clapping noises, but these obviously don't have a communicative function.

Nests at any time of year, whenever food abundant (nests recorded in virtually all months in Ethiopia (2 Ash, J. S., and J. Atkins (2009). Birds of Ethiopia and Eritrea: An Atlas of Distribution. Christopher Helm, London, UK. Close ) and S Africa) (10 Tarboton, W. (2001). A Guide to the Nests and Eggs of Southern African Birds. Struik Publishers, Cape Town, South Africa. Close ), usually to fledge chicks in period of food abundance in summer rainy season (e.g. in Aug–Mar S from Zambia) (1 Ferguson-Lees, J., and D. A. Christie (2001). Raptors of the World. Christopher Helm, London, UK. Close ). Territory of 25–45 km². Each pair places large, saucer-shaped (10 Tarboton, W. (2001). A Guide to the Nests and Eggs of Southern African Birds. Struik Publishers, Cape Town, South Africa. Close ) nest platform (1·5–2·5 m wide and 20–30 cm thick) (10 Tarboton, W. (2001). A Guide to the Nests and Eggs of Southern African Birds. Struik Publishers, Cape Town, South Africa. Close ) of sticks, densely lined with grass, wool and mammal dung (1 Ferguson-Lees, J., and D. A. Christie (2001). Raptors of the World. Christopher Helm, London, UK. Close ), usually 3·0–7·5 m above ground, sometimes up to 36 m up (1 Ferguson-Lees, J., and D. A. Christie (2001). Raptors of the World. Christopher Helm, London, UK. Close ), on top of low tree, often a flat-topped Acacia (2 Ash, J. S., and J. Atkins (2009). Birds of Ethiopia and Eritrea: An Atlas of Distribution. Christopher Helm, London, UK. Close ), but exotic trees (e.g., wattles, pines and pyracanthas) also used (10 Tarboton, W. (2001). A Guide to the Nests and Eggs of Southern African Birds. Struik Publishers, Cape Town, South Africa. Close ); nest may be reused, but usually a new one is constructed for separate breeding attempt; nest-building may sometimes continue indefinitely, without laying (10 Tarboton, W. (2001). A Guide to the Nests and Eggs of Southern African Birds. Struik Publishers, Cape Town, South Africa. Close ). Clutch 1–3 eggs (rarely four) (10 Tarboton, W. (2001). A Guide to the Nests and Eggs of Southern African Birds. Struik Publishers, Cape Town, South Africa. Close ), normally two, pale white with very sparse dark markings (10 Tarboton, W. (2001). A Guide to the Nests and Eggs of Southern African Birds. Struik Publishers, Cape Town, South Africa. Close ), mean size 78 mm × 56 mm (10 Tarboton, W. (2001). A Guide to the Nests and Eggs of Southern African Birds. Struik Publishers, Cape Town, South Africa. Close ), laid at intervals of 2–3 days (10 Tarboton, W. (2001). A Guide to the Nests and Eggs of Southern African Birds. Struik Publishers, Cape Town, South Africa. Close ); incubation by both sexes, period 42–46 days, change-over made up to six times per day (10 Tarboton, W. (2001). A Guide to the Nests and Eggs of Southern African Birds. Struik Publishers, Cape Town, South Africa. Close ); chicks hatch in pale grey down with short straight bill, second dark grey down by three weeks, well feathered by six weeks; nestling period variable, 64 (1 Ferguson-Lees, J., and D. A. Christie (2001). Raptors of the World. Christopher Helm, London, UK. Close )–106 days, usually 75–90 days (1 Ferguson-Lees, J., and D. A. Christie (2001). Raptors of the World. Christopher Helm, London, UK. Close ); young can remain dependent for 62–105 days (1 Ferguson-Lees, J., and D. A. Christie (2001). Raptors of the World. Christopher Helm, London, UK. Close ). Only rarely three chicks raised, but pair may have successive broods with intervals of less than a month between them. Infanticide recently documented in Tanzania, but reasons unknown (11 Morlan, J. and Scott, S. (2016). Photospot: Infanticide in the Secretary-bird Sagittarius serpentarius in Tanzania. Bull. Afr. Bird Club. 23(1): 99–103. Close ). In study in Kgalagadi Transfrontier Park, straddling NW South Africa and SW Botswana, in 1988–1990, total of 26 chicks hatched, of which almost all (23) fledged successfully, and productivity was 2·2 young fledged per breeding attempt per year (12 Herholdt, J. J. and Anderson, M. D. (2006). Observations on the population and breeding status of the African White-backed Vulture, the Black-chested Snake Eagle, and the Secretarybird in the Kgalagadi Transfrontier Park. Ostrich. 77(3&4): 127–135. Close ).

VULNERABLE. Recently uplisted (13 Demey, R., G. M. Kirwan, and P. Lack (2011). Africa Round-up. Category changes of threatened birds. Bulletin of the African Bird Club 18(2):138. Close ). CITES II. Variously common to rare and localized; recent evidence suggests rapid decline across its huge range. Often locally common, both in protected natural areas and in various forms of extensive agriculture; apparently always uncommon in Malawi (14 Dowsett-Lemaire, F. (2006). A Contribution to the Ornithology of Malawi. Tauraco Research Report 8. Tauraco Press, Liège, Belgium. Close ), and never common in Uganda, where now largely confined to national parks in N (15 Carswell, M., D. Pomeroy, J. Reynolds, and H. Tushabe (2005). The Bird Atlas of Uganda. British Ornithologists’ Club and British Ornithologists' Union, Oxford, UK. Close ). According to BirdLife, no reliable estimates of global population available, but surveys suggest that total does not exceed five figures. Has not been seen anywhere in West Africa in recent years and is now considered the most threatened raptor in that region (16 Thiollay, J.-M. (2006). The decline of raptors in West Africa: long-term assessment and the role of protected areas. Ibis. 148(2): 240–254. Close , 17 Thiollay, J.-M. (2007). Raptor declines in West Africa: comparisons between protected, buffer and cultivated areas. Oryx. 41(3): 322-329. Close ). Pertinent records, local surveys and other observations appear to indicate decreases in many areas, suggesting that this species is undergoing rapid decline; this particularly evident in Tanzania since late 1990s and in South Africa between 1987–1991 and 2007–2010 (18 Baker, N., Brouwer, J., Baker, L., Sinclair, T., Harebottle, D., and Buij, R. (2011). The status of the Secretarybird Sagittarius serpentarius with special reference to Tanzania and declines across the continent. A preliminary report to the UK CITES Scientific Authority (Fauna). Close ). In 1990s, more than 1000 breeding pairs thought to occur in former Transvaal Province of NE South Africa alone, and in E Karoo  densities apparently increased during mid 1990s from 0·71 birds/100 km to 1·9 birds/100 km, possibly owing to changes in farming and locust-control practices (19 Anderson, M.D. (1998). The Karoo large terrestrial bird survey. Ostrich. P. 342 in:. Close ). Although this species may benefit from deforestation, any such effects may be outweighed by adverse impacts of spreading cultivation and urbanization (1 Ferguson-Lees, J., and D. A. Christie (2001). Raptors of the World. Christopher Helm, London, UK. Close , 20 Hofmeyr, S.D., Symes, C.T. and Underhill, L.G. (2014). Secretarybird Sagittarius serpentarius population trends and ecology: insights from South African citizen science data. PLOS One. 9(5): e96772. Close ); similarly, excessive burning of grasslands can reduce populations of prey species, and intensive livestock grazing probably results in degradation of habitat (18 Baker, N., Brouwer, J., Baker, L., Sinclair, T., Harebottle, D., and Buij, R. (2011). The status of the Secretarybird Sagittarius serpentarius with special reference to Tanzania and declines across the continent. A preliminary report to the UK CITES Scientific Authority (Fauna). Close ). Human disturbance, e.g. by herders, likely to have negative impact on breeding. Other potential causes of declines include collisions with fences and power lines (20 Hofmeyr, S.D., Symes, C.T. and Underhill, L.G. (2014). Secretarybird Sagittarius serpentarius population trends and ecology: insights from South African citizen science data. PLOS One. 9(5): e96772. Close ), poisoning by insecticides (20 Hofmeyr, S.D., Symes, C.T. and Underhill, L.G. (2014). Secretarybird Sagittarius serpentarius population trends and ecology: insights from South African citizen science data. PLOS One. 9(5): e96772. Close ), direct hunting and nest-robbing. Although this raptor is captured and traded in apparently small numbers, it is unknown how many individuals die in captivity or in transit. Effects of severe droughts in some areas are exacerbated by aforementioned anthropogenic threats. Has been recorded as drowning in steep-sided farm reservoirs in S Africa (21 Anderson, M. D., A. W. A. Maritz, and E. Oosthuysen (1999) Raptors drowning in farm reservoirs in South Africa. Ostrich 70:139–144. Close ). Often protected in recognition of snake- and rodent-killing abilities, but sometimes persecuted at low, accessible nest-sites. Proposed conservation actions include establishment of a co-ordinated continent-wide monitoring programme to obtain accurate and up-to-date estimate of this raptor's population and to determine its current trends. In areas where it is declining, it is important to raise awareness among local inhabitants, especially livestock-herders, of threats facing this species. Equally, it is essential to monitor the capture and trade of the species and to make efforts to prevent such activities. Occurs in a number of national parks and other protected areas across its very large range; alarmingly, however, recently reported to be declining in Kruger National Park, South Africa (20 Hofmeyr, S.D., Symes, C.T. and Underhill, L.G. (2014). Secretarybird Sagittarius serpentarius population trends and ecology: insights from South African citizen science data. PLOS One. 9(5): e96772. Close ). Has been bred several times in captivity.