The secretarybird or secretary bird (''Sagittarius serpentarius'') is a large, mostly terrestrial
bird of prey
Birds of prey or predatory birds, also known as raptors, are hypercarnivorous bird species that actively hunt and feed on other vertebrates (mainly mammals, reptiles and other smaller birds). In addition to speed and strength, these predat ...
.
Endemic
Endemism is the state of a species being found in a single defined geographic location, such as an island, state, nation, country or other defined zone; organisms that are indigenous to a place are not endemic to it if they are also found else ...
to
Africa
Africa is the world's second-largest and second-most populous continent, after Asia in both cases. At about 30.3 million km2 (11.7 million square miles) including adjacent islands, it covers 6% of Earth's total surface area ...
, it is usually found in the open grasslands and
savanna
A savanna or savannah is a mixed woodland- grassland (i.e. grassy woodland) ecosystem characterised by the trees being sufficiently widely spaced so that the canopy does not close. The open canopy allows sufficient light to reach the ground ...
of the
sub-Saharan region.
John Frederick Miller described the species in 1779. Although a member of the order
Accipitriformes
The Accipitriformes (; from Latin ''accipiter''/''accipitri-'' "hawk", and New Latin ''-formes'' "having the form of") are an order of birds that includes most of the diurnal birds of prey, including hawks, eagles, vultures, and kites, but not f ...
, which also includes many other
diurnal birds of prey such as
kites
A kite is a tethered heavier-than-air or lighter-than-air craft with wing surfaces that react against the air to create lift and drag forces. A kite consists of wings, tethers and anchors. Kites often have a bridle and tail to guide the face ...
,
hawk
Hawks are birds of prey of the family Accipitridae. They are widely distributed and are found on all continents except Antarctica.
* The subfamily Accipitrinae includes goshawks, sparrowhawks, sharp-shinned hawks and others. This subfa ...
s,
vulture
A vulture is a bird of prey that scavenges on carrion. There are 23 extant species of vulture (including Condors). Old World vultures include 16 living species native to Europe, Africa, and Asia; New World vultures are restricted to North and ...
s, and
harriers, it is placed in its own family,
Sagittariidae.
The secretarybird is instantly recognizable as a very large bird with an eagle-like body on
crane-like legs that give the bird a height of as much as . The sexes are similar in appearance. Adults have a featherless red-orange face and predominantly grey plumage, with a flattened dark crest and black
flight feather
Flight feathers (''Pennae volatus'') are the long, stiff, asymmetrically shaped, but symmetrically paired pennaceous feathers on the wings or tail of a bird; those on the wings are called remiges (), singular remex (), while those on the tai ...
s and thighs. It also has very long eyelashes.
Breeding can take place at any time of year, but tends to be late in the dry season. The nest is built at the top of a thorny tree, and a clutch of one to three eggs is laid. In years with plentiful food all three young can survive to fledgling. The secretarybird hunts and catches prey on the ground, often stomping on victims to kill them. Insects and small vertebrates make up its diet.
Although the secretarybird occurs over a large range, the results of localised surveys suggest that the total population is experiencing a rapid decline, probably as a result of
habitat degradation
Habitat destruction (also termed habitat loss and habitat reduction) is the process by which a natural habitat becomes incapable of supporting its native species. The organisms that previously inhabited the site are displaced or dead, thereby ...
. The species is therefore classed as
Endangered
An endangered species is a species that is very likely to become extinct in the near future, either worldwide or in a particular political jurisdiction. Endangered species may be at risk due to factors such as habitat loss, poaching and inva ...
by the
International Union for Conservation of Nature
The International Union for Conservation of Nature (IUCN; officially International Union for Conservation of Nature and Natural Resources) is an international organization working in the field of nature conservation and sustainable use of natu ...
. It appears on the
coats of arms
A coat of arms is a heraldic visual design on an escutcheon (i.e., shield), surcoat, or tabard (the latter two being outer garments). The coat of arms on an escutcheon forms the central element of the full heraldic achievement, which in its wh ...
of
Sudan
Sudan ( or ; ar, السودان, as-Sūdān, officially the Republic of the Sudan ( ar, جمهورية السودان, link=no, Jumhūriyyat as-Sūdān), is a country in Northeast Africa. It shares borders with the Central African Republic t ...
and
South Africa
South Africa, officially the Republic of South Africa (RSA), is the southernmost country in Africa. It is bounded to the south by of coastline that stretch along the South Atlantic and Indian Oceans; to the north by the neighbouring countri ...
.
Taxonomy
The Dutch naturalist
Arnout Vosmaer
Arnout Vosmaer (23 September 1720 – 15 January 1799) was a Dutch naturalist and collection curator.
Life
Arnout Vosmaer was born in Rotterdam on 23 September 1720 and died in The Hague on 15 January 1799. Very little is known about his personal ...
described the secretarybird in 1769 on the basis of a live specimen that had been sent to Holland from the
Cape of Good Hope
The Cape of Good Hope ( af, Kaap die Goeie Hoop ) ;''Kaap'' in isolation: pt, Cabo da Boa Esperança is a rocky headland on the Atlantic coast of the Cape Peninsula in South Africa.
A common misconception is that the Cape of Good Hope is t ...
two years earlier by an official of the
Dutch East India Company
The United East India Company ( nl, Verenigde Oostindische Compagnie, the VOC) was a chartered company established on the 20th March 1602 by the States General of the Netherlands amalgamating existing companies into the first joint-stock ...
. Vosmaer suggested that the species was called "sagittarius" by the Dutch settlers because its gait was thought to resemble an archer's. He also mentioned that it was known as the "secretarius" by farmers who had domesticated the bird to combat pests around their homesteads, and proposed that the word "secretarius" might be a corruption of "sagittarius". Ian Glenn of the
University of the Free State
The University of the Free State is a multi-campus public university in Bloemfontein, the capital of the Free State and the judicial capital of South Africa. It was first established as an institution of higher learning in 1904 as a tertiary se ...
suggests that Vosmaer's "sagittarius" is a misheard or mis-transcribed form of "secretarius", rather than the other way around.
In 1779 the English illustrator
John Frederick Miller included a coloured plate of the secretarybird in his ''Icones animalium et plantarum'' and coined the
binomial name
In taxonomy, binomial nomenclature ("two-term naming system"), also called nomenclature ("two-name naming system") or binary nomenclature, is a formal system of naming species of living things by giving each a name composed of two parts, bot ...
''Falco serpentarius''. As the oldest published specific name, ''serpentarius'' has
priority over later scientific names.
[ The species was assigned to its own ]genus
Genus ( plural genera ) is a taxonomic rank used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In the hierarchy of biological classification, genus com ...
''Sagittarius'' in 1783 by the French naturalist Johann Hermann
Johann, or Jean-Frederic, Hermann, or Herrmann, (31 December 1738 in Barr, Alsace – 4 October 1800 in Strasbourg) was a French physician and naturalist.
In 1769 he was appointed professor of medicine at the School of Public Health of Strasbo ...
in his ''Tabula affinitatum animalium''. The generic name ''Sagittarius'' is Latin
Latin (, or , ) is a classical language belonging to the Italic branch of the Indo-European languages. Latin was originally a dialect spoken in the lower Tiber area (then known as Latium) around present-day Rome, but through the power of the ...
for "archer", and the specific epithet
In taxonomy, binomial nomenclature ("two-term naming system"), also called nomenclature ("two-name naming system") or binary nomenclature, is a formal system of naming species of living things by giving each a name composed of two parts, bot ...
''serpentarius'' is from Latin ''serpens'' meaning "serpent" or "snake". A second edition of Miller's plates was published in 1796 as ''Cimelia physica'', with added text by English naturalist George Shaw George Shaw may refer to:
* George Shaw (biologist) (1751–1813), English botanist and zoologist
* George B. Shaw (1854–1894), U.S. Representative from Wisconsin
* George Bernard Shaw (1856–1950), Irish playwright
* George C. Shaw (1866–196 ...
, who named it ''Vultur serpentarius''. The French naturalist Georges Cuvier
Jean Léopold Nicolas Frédéric, Baron Cuvier (; 23 August 1769 – 13 May 1832), known as Georges Cuvier, was a French natural history, naturalist and zoology, zoologist, sometimes referred to as the "founding father of paleontology". Cuvier ...
erected the genus ''Serpentarius'' in 1798, and the German naturalist Johann Karl Wilhelm Illiger
Johann Karl Wilhelm Illiger (19 November 1775 – 10 May 1813) was a German entomologist and zoologist.
Illiger was the son of a merchant in Braunschweig. He studied under the entomologist Johann Christian Ludwig Hellwig, Johann Hellwig, and late ...
erected the (now synonymous[) genus ''Gypogeranus'' from the Ancient Greek words ''gyps'' "vulture" and ''geranos'' "crane" in 1811.
In 1835 the Irish naturalist ]William Ogilby
William Ogilby (1805–1873) was an Irish-born zoologist who was at the forefront of classification and naming of animal species in the 1830s and served as Secretary of the Zoological Society of London from 1839 to 1847. He removed to Ireland ...
spoke at a meeting of the Zoological Society of London
The Zoological Society of London (ZSL) is a charity devoted to the worldwide conservation of animals and their habitats. It was founded in 1826. Since 1828, it has maintained the London Zoo, and since 1931 Whipsnade Park.
History
On 29 ...
and proposed three species of secretarybird, distinguishing those from Senegambia
The Senegambia (other names: Senegambia region or Senegambian zone,Barry, Boubacar, ''Senegambia and the Atlantic Slave Trade'', (Editors: David Anderson, Carolyn Brown; trans. Ayi Kwei Armah; contributors: David Anderson, American Council of Le ...
as having broader crest feathers than those from South Africa, and reporting a distinct species from the Philippines based on the writings of Pierre Sonnerat
Pierre Sonnerat (18 August 1748 – 31 March 1814) was a French naturalist, colonial administrator, writer and explorer. He described numerous species of plants and animals on his travels and is honoured in the genus ''Sonneratia'' and in other ...
in his ''Voyage à la Nouvelle-Guinée''. There is no other evidence this taxon existed. Despite its large range, the secretarybird is considered monotypic
In biology, a monotypic taxon is a taxonomic group (taxon) that contains only one immediately subordinate taxon. A monotypic species is one that does not include subspecies or smaller, infraspecific taxa. In the case of genera, the term "unispec ...
: no subspecies
In biological classification, subspecies is a rank below species, used for populations that live in different areas and vary in size, shape, or other physical characteristics (morphology), but that can successfully interbreed. Not all species ...
are recognised.
The evolutionary relationship of the secretarybird to other raptors had long puzzled ornithologists. The species was usually placed in its own family Sagittariidae within the order Falconiformes
The order Falconiformes () is represented by the extant family Falconidae (falcons and caracaras) and a handful of enigmatic Paleogene species. Traditionally, the other bird of prey families Cathartidae (New World vultures and condors), Sagitt ...
. A large molecular phylogenetic
Molecular phylogenetics () is the branch of phylogeny that analyzes genetic, hereditary molecular differences, predominantly in DNA sequences, to gain information on an organism's evolutionary relationships. From these analyses, it is possible to ...
study published in 2008 found that the secretarybird was sister
A sister is a woman or a girl who shares one or more parents with another individual; a female sibling. The male counterpart is a brother. Although the term typically refers to a familial relationship, it is sometimes used endearingly to refer to ...
to a clade
A clade (), also known as a monophyletic group or natural group, is a group of organisms that are monophyletic – that is, composed of a common ancestor and all its lineal descendants – on a phylogenetic tree. Rather than the English term, ...
containing the ospreys in the family Pandionidae
''Pandion'' is a genus of birds of prey, known as ospreys, the only genus of family Pandionidae. Most taxonomic treatments have regarded this genus as describing a single extant species, separated to subspecies or races, while some treatments rec ...
and the kites, hawks and eagles in the family Accipitridae
The Accipitridae is one of the three families within the order Accipitriformes, and is a family of small to large birds with strongly hooked bills and variable morphology based on diet. They feed on a range of prey items from insects to medium-s ...
. The same study found that the falcons in the order Falconiformes were only distantly related to the other diurnal birds of prey. The families Cathartidae
The New World vulture or condor family, Cathartidae, contains seven extant species in five genera. It includes five extant vultures and two extant condors found in warm and temperate areas of the Americas. The "New World" vultures were widespre ...
, Sagittariidae, Pandionidae and Accipitridae were therefore moved from Falconiformes to the resurrected Accipitriformes
The Accipitriformes (; from Latin ''accipiter''/''accipitri-'' "hawk", and New Latin ''-formes'' "having the form of") are an order of birds that includes most of the diurnal birds of prey, including hawks, eagles, vultures, and kites, but not f ...
. A later molecular phylogenetic study published in 2015 confirmed these relationships.
The fossil record of the secretarybird may be affected by the pull of the recent, which through over-sampling of younger records might lead to faulty conclusions about older or ancestral forms. Recent fossils which include the secretarybird’s direct ancestors are not known, possibly due to the less resilient skeletons of birds compared to other vertebrates, or a more localized geographic history in the last 5 million years.
The earliest fossil
A fossil (from Classical Latin , ) is any preserved remains, impression, or trace of any once-living thing from a past geological age. Examples include bones, shells, exoskeletons, stone imprints of animals or microbes, objects preserved ...
s associated with the family are two species from the genus ''Pelargopappus
''Pelargopappus'' is an extinct genus of raptor related to the secretarybird that lived in early Miocene France. Only one species, the type species ''P. magnus'' is officially recognized. A second species, ''P. schlosseri'' from the mid-and lat ...
''. The two species, from the Oligocene
The Oligocene ( ) is a geologic epoch of the Paleogene Period and extends from about 33.9 million to 23 million years before the present ( to ). As with other older geologic periods, the rock beds that define the epoch are well identified but the ...
and Miocene
The Miocene ( ) is the first geological epoch of the Neogene Period and extends from about (Ma). The Miocene was named by Scottish geologist Charles Lyell; the name comes from the Greek words (', "less") and (', "new") and means "less recen ...
respectively, were discovered in France. The feet in these fossils are more like those of the Accipitridae; it is suggested that these characteristics are primitive features within the family. In spite of their age, the two species are not thought to be ancestral to the secretarybird. Though strongly convergent with the modern secretarybird, the extinct raptor ''Apatosagittarius
''Apatosagittarius'' is an extinct monotypic genus of Accipitridae from the Late Miocene of Nebraska. Only one species has been described, ''Apatosagittarius terrenus''. The genus name, which Feduccia and Voorhies translate as "false secretaryb ...
'' is thought to be an accipitrid.
The International Ornithologists' Union
The International Ornithologists' Union, formerly known as the International Ornithological Committee, is a group of about 200 international ornithologists, and is responsible for the International Ornithological Congress and other international ...
has designated "secretarybird" the official common name for the species.[ In 1780 the French polymath ]Georges-Louis Leclerc, Comte de Buffon
Georges-Louis Leclerc, Comte de Buffon (; 7 September 1707 – 16 April 1788) was a French naturalist, mathematician, cosmologist, and encyclopédiste.
His works influenced the next two generations of naturalists, including two prominent Fr ...
suggested that the name secretary/secrétaire had been chosen because of the long quill-like feathers at the top of the bird's neck, reminiscent of a quill pen behind the ear of an ancient scribe. In 1977, C. Hilary Fry of Aberdeen University
, mottoeng = The fear of the Lord is the beginning of wisdom
, established =
, type = Public research universityAncient university
, endowment = £58.4 million (2021)
, budget ...
suggested that "secretary" is from the French ''secrétaire'', a corruption of the Arabic ''saqr et-tair'' meaning either "hawk of the semi-desert" or "hawk that flies". Glenn has dismissed this etymology on the grounds that there is no evidence that the name came through French, instead supporting Buffon's etymology; namely, that the word comes from the Dutch ''secretaris'' "secretary", used by settlers in South Africa.[
]
Description
The secretarybird is instantly recognisable as a very large terrestrial bird with an eagle-like head and body on crane-like legs. It stands about tall.[ It has a length of between and a wingspan of between .] The weight ranges from , with a mean of . The averages and the tail is : both factor into making it both taller and longer than any other species of raptor. The neck is not especially long, and can only be lowered down to the intertarsal joint, so birds must stoop to reach down to the ground.
During flight, two elongated central feathers of the tail extend beyond the feet, and the neck stretches out like a stork
Storks are large, long-legged, long-necked wading birds with long, stout bills. They belong to the family called Ciconiidae, and make up the order Ciconiiformes . Ciconiiformes previously included a number of other families, such as herons an ...
.[ The plumage of the crown, upperparts, and lesser and median wing coverts is blue-grey, and the underparts and underwing coverts are lighter grey to grey-white. The crest is made up of long black feathers arising from the nape. The scapulars, primary and secondary ]flight feather
Flight feathers (''Pennae volatus'') are the long, stiff, asymmetrically shaped, but symmetrically paired pennaceous feathers on the wings or tail of a bird; those on the wings are called remiges (), singular remex (), while those on the tai ...
s, rump and thighs are black, while the uppertail coverts are white, though barred with black in some individuals.[ The tail is wedge-shaped with white tipping, marbled grey and black colouring at the base, and two broad black bands, one at the base and the other at the end.][
Sexes resemble one another, although the male tends to have longer tail feathers, more head plumes, a shorter head and more blue-grey plumage. Adults have a featherless red-orange face with pale brown irises and a yellow ]cere
The beak, bill, or rostrum is an external anatomical structure found mostly in birds, but also in turtles, non-avian dinosaurs and a few mammals. A beak is used for eating, preening, manipulating objects, killing prey, fighting, probing for food ...
. The legs and feet are pinkish grey, the upper legs clad in black feathers. The toes are short—around 20% of the length of those of an eagle of the same size—and stout, so that the bird is unable to grasp objects with its feet. The rear toe is small and the three forward facing toes are connected at the base by a small web.[ Immature birds have yellow rather than orange bare skin on their faces, more brownish plumage, shorter tail feathers and greyish rather than brown irises.][
Adults are normally silent but can utter a deep guttural croaking noise in nuptial displays or at nests.][ Secretarybirds make this sound when greeting their mates or in a threat display or fight against other birds, sometimes throwing their head backwards at the same time. When alarmed, the secretarybird may emit a high-pitched croak. Mated pairs at the nest make soft clucking or whistling calls.][ Chicks make a sharp sound heard as "chee-uk-chee-uk-chee-uk" for their first 30 days.][
]
Distribution and habitat
The secretarybird is endemic to sub-Saharan Africa
Sub-Saharan Africa is, geographically, the area and regions of the continent of Africa that lies south of the Sahara. These include West Africa, East Africa, Central Africa, and Southern Africa. Geopolitically, in addition to the List of sov ...
and is generally non-migratory
Bird migration is the regular seasonal movement, often north and south along a flyway, between breeding and wintering grounds. Many species of bird migrate. Migration carries high costs in predation and mortality, including from hunting by ...
, though it may be locally nomadic as it follows rainfall and the resulting abundance of prey.[ Its range extends from ]Senegal
Senegal,; Wolof: ''Senegaal''; Pulaar: 𞤅𞤫𞤲𞤫𞤺𞤢𞥄𞤤𞤭 (Senegaali); Arabic: السنغال ''As-Sinighal'') officially the Republic of Senegal,; Wolof: ''Réewum Senegaal''; Pulaar : 𞤈𞤫𞤲𞤣𞤢𞥄𞤲𞤣𞤭 ...
to Somalia
Somalia, , Osmanya script: 𐒈𐒝𐒑𐒛𐒐𐒘𐒕𐒖; ar, الصومال, aṣ-Ṣūmāl officially the Federal Republic of SomaliaThe ''Federal Republic of Somalia'' is the country's name per Article 1 of thProvisional Constituti ...
and south to Western Cape
The Western Cape is a province of South Africa, situated on the south-western coast of the country. It is the fourth largest of the nine provinces with an area of , and the third most populous, with an estimated 7 million inhabitants in 2020 ...
, South Africa
South Africa, officially the Republic of South Africa (RSA), is the southernmost country in Africa. It is bounded to the south by of coastline that stretch along the South Atlantic and Indian Oceans; to the north by the neighbouring countri ...
.[
The species is also found at a variety of ]elevation
The elevation of a geographic location is its height above or below a fixed reference point, most commonly a reference geoid, a mathematical model of the Earth's sea level as an equipotential gravitational surface (see Geodetic datum § Vert ...
s, from the coastal plain
A coastal plain is flat, low-lying land adjacent to a sea coast. A fall line commonly marks the border between a coastal plain and a piedmont area. Some of the largest coastal plains are in Alaska and the southeastern United States. The Gulf Coa ...
s to the highlands. The secretarybird prefers open grassland
A grassland is an area where the vegetation is dominated by grasses (Poaceae). However, sedge (Cyperaceae) and rush (Juncaceae) can also be found along with variable proportions of legumes, like clover, and other herbs. Grasslands occur natur ...
s, savanna
A savanna or savannah is a mixed woodland- grassland (i.e. grassy woodland) ecosystem characterised by the trees being sufficiently widely spaced so that the canopy does not close. The open canopy allows sufficient light to reach the ground ...
s and shrubland
Shrubland, scrubland, scrub, brush, or bush is a plant community characterized by vegetation dominated by shrubs, often also including grasses, herbs, and geophytes. Shrubland may either occur naturally or be the result of human activity. It m ...
(Karoo
The Karoo ( ; from the Afrikaans borrowing of the South Khoekhoe !Orakobab or Khoemana word ''ǃ’Aukarob'' "Hardveld") is a semi-desert natural region of South Africa. No exact definition of what constitutes the Karoo is available, so its ext ...
) rather than forest
A forest is an area of land dominated by trees. Hundreds of definitions of forest are used throughout the world, incorporating factors such as tree density, tree height, land use, legal standing, and ecological function. The United Nations' ...
s and dense shrubbery
A shrubbery, shrub border or shrub garden is a part of a garden where shrubs, mostly flowering species, are thickly planted. The original shrubberies were mostly sections of large gardens, with one or more paths winding through it, a less-rememb ...
that may impede its cursorial
A cursorial organism is one that is adapted specifically to run. An animal can be considered cursorial if it has the ability to run fast (e.g. cheetah) or if it can keep a constant speed for a long distance (high endurance). "Cursorial" is often us ...
existence.[ More specifically, it prefers areas with grass under high and avoids those with grass over high. It is rarer in grasslands in northern parts of its range that otherwise appear similar to areas in southern Africa where it is abundant, suggesting it may avoid hotter regions. It also avoids deserts.][
]
Behaviour and ecology
Secretarybirds are not generally gregarious
Sociality is the degree to which individuals in an animal population tend to associate in social groups (gregariousness) and form cooperative societies.
Sociality is a survival response to evolutionary pressures. For example, when a mother wasp ...
aside from pairs and their offspring. They usually roost in trees of the genus ''Acacia
''Acacia'', commonly known as the wattles or acacias, is a large genus of shrubs and trees in the subfamily Mimosoideae of the pea family Fabaceae. Initially, it comprised a group of plant species native to Africa and Australasia. The genus na ...
'' or '' Balanites'', or even introduced pine trees in South Africa.[ They set off 1–2 hours after dawn, generally after spending some time ]preening
Preening is a found in birds that involves the use of the beak to position feathers, interlock feather that have become separated, clean plumage, and keep ectoparasites in check. Feathers contribute significantly to a bird's insulation, waterp ...
.[ Mated pairs roost together but may forage separately, though often remaining in sight of one another. They pace around at a speed of , taking 120 steps per minute on average.][ After spending much of the day on the ground, secretarybirds return at dusk,] moving downwind
Windward () and leeward () are terms used to describe the direction of the wind. Windward is ''upwind'' from the point of reference, i.e. towards the direction from which the wind is coming; leeward is ''downwind'' from the point of reference ...
before flying in upwind.[ Birds encountered singly are often unattached males, their territories generally in less suitable areas. Conversely, larger groups of up to 50 individuals may be present at an area with a localised resource such as a waterhole in a dry area or an irruption of rodents or locusts fleeing a fire.][
Secretarybirds soar with their primary feathers splayed to manage turbulence. Their wings can flap, though in a slow laborious manner and requiring uplift to be sustained; otherwise they may become exhausted. In the heat of the day, they use ]thermal
A thermal column (or thermal) is a rising mass of buoyant air, a convective current in the atmosphere, that transfers heat energy vertically. Thermals are created by the uneven heating of Earth's surface from solar radiation, and are an example ...
s to rise up to above the ground.[
The lifespan is thought to be 10 to 15 years in the wild,][ with the oldest confirmed by banding to be 5 years from a nestling banded on 23 July 2011 in ]Bloemfontein
Bloemfontein, ( ; , "fountain of flowers") also known as Bloem, is one of South Africa's three capital cities and the capital of the Free State (province), Free State province. It serves as the country's judicial capital, along with legisla ...
and recovered away in Mpumalanga
Mpumalanga () is a province of South Africa. The name means "East", or literally "The Place Where the Sun Rises" in the Swazi, Xhosa, Ndebele and Zulu languages. Mpumalanga lies in eastern South Africa, bordering Eswatini and Mozambique. It ...
on 7 June 2016, and up to 19 years in captivity.[ Secretarybirds, like all birds, have haematozoan blood parasites that include ''Leucocytozoon beaurepairei'' Dias 1954 recorded from Mozambique. Wild birds from Tanzania have been found to have ''Hepatozoon ellisgreineri'', a genus that is unique among avian haematozoa in maturing within granulocytes, mainly heterophils. Ectoparasites include the lice ''Neocolpocephalum cucullare'' (Giebel) and ''Falcolipeurus secretarius'' (Giebel).
]
Breeding
Secretarybirds form monogamous pairs and defend a large territory of around . They can breed at any time of the year, more frequently in the late dry season. During courtship, they exhibit a nuptial display by soaring high with undulating flight patterns and calling with guttural croaking. Males and females can also perform a ground display by chasing each other with their wings up and back, which is also the way they defend their territory. They mate either on the ground or in trees.
The nest is built by both sexes at the top of a dense thorny tree, often an ''Acacia'', at a height of between above the ground. The nest is constructed as a relatively flat platform of sticks across with a depth . The shallow depression is lined with grass and the occasional piece of dung.[
Eggs are laid at 2- to 3-day intervals until the clutch of 1–3 eggs is complete. The elongated chalky bluish green or white eggs average and weigh .][ Both parents incubate the eggs, starting as soon as the first egg is laid, but it is usually the female that remains on the nest overnight. The incubating parent greets its partner when it returns with a display of bowing and bobbing its head with neck extended. The tail is held upright with feathers fanned out, and the chest feathers are puffed out.]
The eggs hatch after around 45 days at intervals of 2–3 days. Both parents feed the young. The adults regurgitate food onto the floor of the nest and then pick up items and pass them to the chicks. For the first 2 or 3 weeks after the eggs hatch the parents take turns to stay at the nest with the young. Despite the difference in nestling size due to the asynchronous hatching, little sibling aggression has been observed. Under favourable conditions all chicks from a clutch of three eggs fledge
Fledging is the stage in a flying animal's life between hatching or birth and becoming capable of flight.
This term is most frequently applied to birds, but is also used for bats. For altricial birds, those that spend more time in vulnerable c ...
, but if food is scarce one or more of the chicks will die from starvation. The young may be preyed upon by crows
The Common Remotely Operated Weapon Station (CROWS) is a series of remote weapon stations used by the US military on its armored vehicles and ships. It allows weapon operators to engage targets without leaving the protection of their vehicle. T ...
, ravens, hornbill
Hornbills (Bucerotidae) are a family (biology), family of bird found in tropical and subtropical Africa, Asia and Melanesia. They are characterized by a long, down-curved bill which is frequently brightly coloured and sometimes has a Casque (an ...
s, and large owl
Owls are birds from the order Strigiformes (), which includes over 200 species of mostly solitary and nocturnal birds of prey typified by an upright stance, a large, broad head, binocular vision, binaural hearing, sharp talons, and feathers a ...
s.
The young are born covered in grey-white down that becomes darker grey after two weeks. Their bare facial skin and legs are yellow. Crest feathers appear at 21 days, and flight feathers by 28 days. They can stand up and feed autonomously after 40 days, although the parents still feed the nestlings after that time. At 60 days, the now fully-feathered young start to flap their wings. Their weight gain over this period changes from at hatching, to at 20 days, at 30 days, at 40 days, at 50 days, at 60 days, and at 70 days. The time they leave the nest can be anywhere between 65 and 106 days of age, although it most typically occurs between 75 and 80 days of age. Fledging is accomplished by jumping out of the nest or using a semi-controlled glide to the ground.[
Juveniles remain in their natal range before dispersing when they are between 4 and 7 months of age. The usual age at which they first breed is uncertain but there is a record of a male bird breeding successfully at an age of 2 years and 9 months, which is young for a large raptor.]
Food and feeding
Unlike most birds of prey
Birds of prey or predatory birds, also known as raptors, are hypercarnivorous bird species that actively hunt and feed on other vertebrates (mainly mammals, reptiles and other smaller birds). In addition to speed and strength, these predat ...
, the secretarybird is largely terrestrial
Terrestrial refers to things related to land or the planet Earth.
Terrestrial may also refer to:
* Terrestrial animal, an animal that lives on land opposed to living in water, or sometimes an animal that lives on or near the ground, as opposed to ...
, hunting its prey on foot. Adults hunt in pairs and sometimes as loose familial flocks, stalking through the habitat with long strides. Prey may consist of insect
Insects (from Latin ') are pancrustacean hexapod invertebrates of the class Insecta. They are the largest group within the arthropod phylum. Insects have a chitinous exoskeleton, a three-part body ( head, thorax and abdomen), three pairs ...
s such as locust
Locusts (derived from the Vulgar Latin ''locusta'', meaning grasshopper) are various species of short-horned grasshoppers in the family Acrididae that have a swarming phase. These insects are usually solitary, but under certain circumstanc ...
s, other grasshopper
Grasshoppers are a group of insects belonging to the suborder Caelifera. They are among what is possibly the most ancient living group of chewing herbivorous insects, dating back to the early Triassic around 250 million years ago.
Grasshopp ...
s, wasp
A wasp is any insect of the narrow-waisted suborder Apocrita of the order Hymenoptera which is neither a bee nor an ant; this excludes the broad-waisted sawflies (Symphyta), which look somewhat like wasps, but are in a separate suborder. Th ...
s, and beetle
Beetles are insects that form the order Coleoptera (), in the superorder Endopterygota. Their front pair of wings are hardened into wing-cases, elytra, distinguishing them from most other insects. The Coleoptera, with about 400,000 describ ...
s,[ ]mammal
Mammals () are a group of vertebrate animals constituting the class Mammalia (), characterized by the presence of mammary glands which in females produce milk for feeding (nursing) their young, a neocortex (a region of the brain), fur or ...
s ranging in size from mice
A mouse ( : mice) is a small rodent. Characteristically, mice are known to have a pointed snout, small rounded ears, a body-length scaly tail, and a high breeding rate. The best known mouse species is the common house mouse (''Mus musculus' ...
and rats to hare
Hares and jackrabbits are mammals belonging to the genus ''Lepus''. They are herbivores, and live solitarily or in pairs. They nest in slight depressions called forms, and their young are able to fend for themselves shortly after birth. The ge ...
s, hedgehog
A hedgehog is a spiny mammal of the subfamily Erinaceinae, in the eulipotyphlan family Erinaceidae. There are seventeen species of hedgehog in five genera found throughout parts of Europe, Asia, and Africa, and in New Zealand by introducti ...
s, and mongoose
A mongoose is a small terrestrial carnivorous mammal belonging to the family Herpestidae. This family is currently split into two subfamilies, the Herpestinae and the Mungotinae. The Herpestinae comprises 23 living species that are native to so ...
, crab
Crabs are decapod crustaceans of the infraorder Brachyura, which typically have a very short projecting "tail" (abdomen) ( el, βραχύς , translit=brachys = short, / = tail), usually hidden entirely under the thorax. They live in all the ...
s, spider
Spiders ( order Araneae) are air-breathing arthropods that have eight legs, chelicerae with fangs generally able to inject venom, and spinnerets that extrude silk. They are the largest order of arachnids and rank seventh in total species ...
s, scorpion
Scorpions are predatory arachnids of the order Scorpiones. They have eight legs, and are easily recognized by a pair of grasping pincers and a narrow, segmented tail, often carried in a characteristic forward curve over the back and always end ...
s, millipede
Millipedes are a group of arthropods that are characterised by having two pairs of jointed legs on most body segments; they are known scientifically as the class Diplopoda, the name derived from this feature. Each double-legged segment is a resu ...
s, amphibian
Amphibians are tetrapod, four-limbed and ectothermic vertebrates of the Class (biology), class Amphibia. All living amphibians belong to the group Lissamphibia. They inhabit a wide variety of habitats, with most species living within terres ...
s, lizard
Lizards are a widespread group of squamate reptiles, with over 7,000 species, ranging across all continents except Antarctica, as well as most oceanic island chains. The group is paraphyletic since it excludes the snakes and Amphisbaenia alt ...
s, snake
Snakes are elongated, Limbless vertebrate, limbless, carnivore, carnivorous reptiles of the suborder Serpentes . Like all other Squamata, squamates, snakes are ectothermic, amniote vertebrates covered in overlapping Scale (zoology), scales. Ma ...
s, tortoise
Tortoises () are reptiles of the family Testudinidae of the order Testudines (Latin: ''tortoise''). Like other turtles, tortoises have a turtle shell, shell to protect from predation and other threats. The shell in tortoises is generally hard, ...
s, small birds, bird egg
Bird eggs are laid by the females and range in quantity from one (as in condors) to up to seventeen (the grey partridge). Clutch size may vary latitudinally within a species. Some birds lay eggs even when the eggs have not been fertilized; it is ...
s, and sometimes dead animals killed in grass or bush fires. Larger herbivore
A herbivore is an animal anatomically and physiologically adapted to eating plant material, for example foliage or marine algae, for the main component of its diet. As a result of their plant diet, herbivorous animals typically have mouthpart ...
s are not generally hunted, although there are some reports of secretarybirds killing young gazelle
A gazelle is one of many antelope species in the genus ''Gazella'' . This article also deals with the seven species included in two further genera, '' Eudorcas'' and '' Nanger'', which were formerly considered subgenera of ''Gazella''. A third ...
s and cheetah
The cheetah (''Acinonyx jubatus'') is a large cat native to Africa and central Iran. It is the fastest land animal, estimated to be capable of running at with the fastest reliably recorded speeds being , and as such has evolved specialized ...
cubs. The importance of snakes in the diet has been exaggerated in the past, although they can be locally important and venomous species such as adders and cobras are regularly among the types of snake preyed upon. Secretarybirds do not eat carrion
Carrion () is the decaying flesh of dead animals, including human flesh.
Overview
Carrion is an important food source for large carnivores and omnivores in most ecosystems. Examples of carrion-eaters (or scavengers) include crows, vultures, c ...
.[
The birds often flush prey from tall grass by stomping on the surrounding vegetation. Their crest feathers may raise during a hunt, which may serve to help scare the target and provide shade for the face.][ A bird will chase after prey with the wings spread and kill by striking with swift blows of the feet. Only with small prey items such as wasps will the bird use its bill to pick them directly. There are some reports that, when capturing snakes, a secretarybird will take flight with their prey and then drop them to their death, although this has not been verified. Even with larger prey, food is generally swallowed whole through the birds' considerable gape. Occasionally, like other raptors, they will hold down a food item with their feet while tearing it apart with their bill.][
]
Food that cannot be digested is regurgitated as pellets in diameter and in length. These are dropped on the ground usually near the roost or nest trees.[ The secretarybird has a relatively short digestive tract in comparison to large African birds with more mixed diets, such as the ]kori bustard
The kori bustard (''Ardeotis kori'') is the largest flying bird native to Africa. It is a member of the bustard family, which all belong to the order Otidiformes and are restricted in distribution to the Old World. It is one of the four species ( ...
. The foregut is specialised for the consumption of large amounts of meat and there is little need for the mechanical breakdown of food. The crop
A crop is a plant that can be grown and harvested extensively for profit or subsistence. When the plants of the same kind are cultivated at one place on a large scale, it is called a crop. Most crops are cultivated in agriculture or hydroponic ...
is dilated and the gizzard
The gizzard, also referred to as the ventriculus, gastric mill, and gigerium, is an organ found in the digestive tract of some animals, including archosaurs (pterosaurs, crocodiles, alligators, dinosaurs, birds), earthworms, some gastropods, so ...
is nonmuscular, as in other carnivorous birds. The large intestine has a pair of vestigial ceca as there is no requirement for the fermentative digestion of plant material.
Secretarybirds specialise in stomping their prey until it is killed or immobilised. This method of hunting is commonly applied to lizards or snakes. An adult male trained to strike at a rubber snake on a force plate was found to hit with a force equal to five times its own body weight, with a contact period of only 10–15 milliseconds. This short time of contact suggests that the secretarybird relies on superior visual targeting to determine the precise location of the prey's head. Although little is known about its visual field, it is assumed that it is large, frontal and binocular. Secretarybirds have unusually long legs (nearly twice as long as other ground birds of the same body mass), which is thought to be an adaptation for the bird's unique stomping and striking hunting method. However, these long limbs appear to also lower its running efficiency. Ecophysiologist Steve Portugal and colleagues have hypothesised that the extinct Phorusrhacidae
Phorusrhacids, colloquially known as terror birds, are an extinct clade of large carnivorous flightless birds that were one of the largest species of apex predators in South America during the Cenozoic era; their conventionally accepted temporal ...
(terror birds) may have employed a similar hunting technique to secretarybirds because they are anatomically similar, although they are not closely related.
Secretarybirds rarely encounter other predators, except in the case of tawny eagle
The tawny eagle (''Aquila rapax'') is a large bird of prey. Like all eagles, it belongs to the family ''Accipitridae''. Its heavily feathered legs mark it as a member of the subfamily Aquilinae, also known as booted eagles.Helbig, A. J., Kocum, ...
s, which will steal their kills. Eagles mainly steal larger prey and will attack secretarybirds both singly or in pairs. Secretarybird pairs are sometimes successful in driving the eagles away and may even knock them down and pin them to the ground.[
]
Relationship with humans
Cultural significance
The secretarybird is depicted on an ivory knife handle recovered from Abu Zaidan in Upper Egypt
Upper Egypt ( ar, صعيد مصر ', shortened to , , locally: ; ) is the southern portion of Egypt and is composed of the lands on both sides of the Nile that extend upriver from Lower Egypt in the north to Nubia in the south.
In ancient ...
, dating to the Naqada III
Naqada III is the last phase of the Naqada culture of ancient Egyptian prehistory, dating from approximately 3200 to 3000 BC. It is the period during which the process of state formation, which began in Naqada II, became highly visible, ...
culture (c. 3,200 BC). This and other knife handles indicate the secretarybird most likely occurred historically further north along the Nile.[
]
The secretarybird has traditionally been admired in Africa for its striking appearance and ability to deal with pests and snakes. As such it has often not been disturbed, although this is changing as traditional observances have declined. It is a prominent feature on the coat of arms of South Africa, which was adopted in 2000. With its wings outstretched, it represents growth, and its penchant for killing snakes is symbolic as the protector of the South African state against enemies. It is on the emblem of Sudan
The current national emblem of Sudan was adopted in 1985.
Design
The emblem shows a secretary bird bearing a shield from the time of Muhammad Ahmad, the self-proclaimed Mahdi who briefly ruled Sudan in the 19th century.
Two scrolls are placed ...
, adopted in 1969. It is featured on the Sudanese presidential flag and presidential seal. The secretarybird has been a common motif for African countries on postage stamp
A postage stamp is a small piece of paper issued by a post office, postal administration, or other authorized vendors to customers who pay postage (the cost involved in moving, insuring, or registering mail), who then affix the stamp to the fa ...
s: over a hundred stamps from 37 issuers are known, including some from stamp-issuing entities such as Ajman
Ajman ( ar, عجمان, '; Gulf Arabic: عيمان ʿymān) is the capital of the emirate of Ajman in the United Arab Emirates. It is the fifth-largest city in UAE after Dubai, Abu Dhabi, Sharjah and Al Ain. Located along the Persian Gulf, i ...
, Manama
Manama ( ar, المنامة ', Bahrani Arabic, Bahrani pronunciation: ) is the capital and largest city of Bahrain, with an approximate population of 200,000 people as of 2020. Long an important trading center in the Persian Gulf, Manama is h ...
, and the Maldives
Maldives (, ; dv, ދިވެހިރާއްޖެ, translit=Dhivehi Raajje, ), officially the Republic of Maldives ( dv, ދިވެހިރާއްޖޭގެ ޖުމްހޫރިއްޔާ, translit=Dhivehi Raajjeyge Jumhooriyyaa, label=none, ), is an archipelag ...
, regions where the bird does not exist, as well as the United Nations
The United Nations (UN) is an intergovernmental organization whose stated purposes are to maintain international peace and international security, security, develop friendly relations among nations, achieve international cooperation, and be ...
.
The Maasai people
The Maasai (; sw, Wamasai) are a Nilotic ethnic group inhabiting northern, central and southern Kenya and northern Tanzania. They are among the best-known local populations internationally due to their residence near the many game parks of t ...
call it ''ol-enbai nabo'', or "one arrow", referring to its crest feathers. They have used parts of the bird in traditional medicine: its feathers could be burnt and the resulting smoke inhaled to treat epilepsy, its egg could be consumed with tea twice daily to treat headaches, and its fat could be boiled and drunk for child growth or livestock health. The Xhosa people
The Xhosa people, or Xhosa language, Xhosa-speaking people (; ) are African people who are direct kinsmen of Tswana people, Sotho people and Twa people, yet are narrowly sub grouped by European as Nguni people, Nguni ethnic group whose traditi ...
call the bird ''inxhanxhosi'' and attribute great intelligence to it in folklore. The Zulus
Zulu people (; zu, amaZulu) are a Nguni ethnic group native to Southern Africa. The Zulu people are the largest ethnic group and nation in South Africa, with an estimated 10–12 million people, living mainly in the province of KwaZulu-Na ...
call it ''intungunono''.
The German biologist Ragnar Kinzelbach proposed in 2008 that the secretarybird was recorded in the 13th-century work ''De arte venandi cum avibus
''De Arte Venandi cum Avibus'', literally ''On The Art of Hunting with Birds'', is a Latin treatise on ornithology and falconry written in the 1240s by the Holy Roman Emperor Frederick II. One of the surviving manuscripts is dedicated to his son ...
'' by Holy Roman Emperor Frederick II. Described as ''bistarda deserti'', it was mistaken for a bustard
Bustards, including floricans and korhaans, are large, terrestrial birds living mainly in dry grassland areas and on the steppes of the Old World. They range in length from . They make up the family Otididae (, formerly known as Otidae). Bustards ...
. Frederick most likely gained knowledge of the bird from sources in Egypt. The 16th-century French priest and traveller André Thevet
André Thevet (; ; 1516 – 23 November 1590) was a French Franciscan priest, explorer, cosmographer and writer who travelled to the Near East and to South America in the 16th century. His most significant book was '' The New Found World, or ...
also wrote a description of a mysterious bird in 1558 that has been likened by Kinzelbach to this species.
In the Disney film ''Bedknobs and Broomsticks
''Bedknobs and Broomsticks'' is a 1971 American live-action animated musical fantasy film directed by Robert Stevenson and produced by Bill Walsh for Walt Disney Productions. It is loosely based upon the books '' The Magic Bedknob; or, How t ...
'', one of the residents of Naboombu, the assistant to King Leonidas, is a secretarybird. Both the secretarybird and the king are voiced by Lennie Weinrib
Leonard Weinrib (April 29, 1935 – June 28, 2006) was an American actor, comedian and writer. He is best known for playing the title role in the children's television show ''H.R. Pufnstuf'', Grimace in McDonaldland commercials, the title role in ...
.
Threats and conservation
In 1968 the species became protected under the . The International Union for Conservation of Nature
The International Union for Conservation of Nature (IUCN; officially International Union for Conservation of Nature and Natural Resources) is an international organization working in the field of nature conservation and sustainable use of natu ...
(IUCN) listed the secretarybird in 2016 as a vulnerable species
A vulnerable species is a species which has been Conservation status, categorized by the International Union for Conservation of Nature as being threatened species, threatened with extinction unless the circumstances that are threatened species, ...
and as Endangered
An endangered species is a species that is very likely to become extinct in the near future, either worldwide or in a particular political jurisdiction. Endangered species may be at risk due to factors such as habitat loss, poaching and inva ...
in 2020, due to a recent rapid decline across its entire range. Although widespread, the species is thinly distributed across its range; its population has been estimated in 2016 to be anywhere between 6,700 and 67,000 individuals. Long term monitoring across South Africa between 1987 and 2013 has shown that populations have declined across the country, even in protected areas such as Kruger National Park
Kruger National Park is a South African National Park and one of the largest game reserves in Africa. It covers an area of in the provinces of Limpopo and Mpumalanga in northeastern South Africa, and extends from north to south and from ea ...
due to bush encroachment
Woody plant encroachment (also called bush encroachment, shrub encroachment, woody encroachment, bush thickening, or woody plant proliferation) is a natural phenomenon characterised by the increase in density of woody plants, bushes and shrubs, ...
, an increase in the tall vegetation cover, resulting in loss of open habitat that the species prefers.
As a population, the secretarybird is mainly threatened by loss of habitat due to fragmentation by roads and development and overgrazing of grasslands by livestock. Some adaptation to altered areas has been recorded but the trend is for decline.[
]
In captivity
The first successful rearing of a secretarybird in captivity occurred in 1986 at the Oklahoma City Zoo
The Oklahoma City Zoo and Botanical Garden is a zoo and botanical garden located in Oklahoma City's Adventure District in northeast Oklahoma City, Oklahoma.
The zoo covers and is home to more than 1,900 animals. It is open every day except Tha ...
. Although secretarybirds normally build their nests in the trees in the wild, the captive birds at the zoo built theirs on the ground, which left them open to depredation by local wild mammals. Therefore, the zoo staff removed the eggs from the nest each time they were laid so that they could be incubated and hatched at a safer location. The species has also been bred and reared in captivity at the San Diego Zoo Safari Park
The San Diego Zoo Safari Park, originally named the San Diego Wild Animal Park until 2010, is an 1,800 acre (730 ha) zoo in the San Pasqual Valley area of San Diego, California, near Escondido. It is one of the largest tourist attractions in S ...
.
Notes
References
External links
Xeno-canto: audio recordings of the secretary bird
*
Birdlife Species Factsheet
Secretary Bird on postage stamps
Species text in The Atlas of Southern African Birds
{{featured article
Accipitriformes
Birds described in 1779
Birds of Sub-Saharan Africa
Birds of prey
Birds of prey of Africa
Falconiformes (sensu lato)
Higher-level bird taxa restricted to the Afrotropics
National symbols of South Africa
National symbols of Sudan
Taxa named by John Frederick Miller