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What the sources say

SecretarybirdSagittarius serpentarius

Every figure, record and mechanism on the Secretarybird profile was written from a source, and this is the working table behind it: 50 claims checked word for word against these sources. The left column is what the page says. The right column is the source's own words, copied, not paraphrased; a ... marks a cut and[brackets] an insertion. Open any source and check it yourself.

Profile updated

Source
01

The Peregrine Fund

Secretarybird. The Peregrine Fund.

The page saysthe tallest bird of prey alive
The source saysThe tallest raptor in the world
The page sayson the longest legs of any raptor
The source saysSecretarybirds have the longest legs of any bird of prey
The page saysa body weight of 2.2 to 4.3 kilograms (5 to 9.5 pounds)
The source saysWeight: 5-9.5 pounds (2.2-4.3 kg)Note: SDZWA gives 2.3 to 4.3 kg
The page saysHeavy scales on its lower legs may help protect it while it walks through brush or attacks prey
The source saystheir lower legs have heavy scales that may protect them while walking through the brush or when attacking their prey
The page saysIt patrols the grass on foot for roughly 20 to 30 kilometers (12 to 18 miles) a day
The source saysScientists estimate that Secretarybirds walk anywhere from 12 to 18 miles (20-30 km) a day
The page saysIt lives in open savannas and grasslands south of the Sahara, from Senegal and Somalia down to South Africa
The source saysThe Secretarybird is endemic to sub-Saharan Africa. It ranges from Senegal and Somalia all the way to the tip of South Africa. ... Secretarybirds prefer savannas, scrub, and grasslands
The page saysIt is the only living member of its own bird family, Sagittariidae
The source saysthey are the one and only member of the family Sagittariidae
The page saysA Species in Decline
The source saysSecretarybird populations are declining throughout much of their range
The page saysNumbers are falling across much of its range, and it has vanished from some areas entirely
The source saysSecretarybird populations are declining throughout much of their range and the species has disappeared entirely in some placesNote: Peregrine page is current: it gives the 2020 status, Endangered
The page saysHabitat loss is a huge problem: overgrazed land leaves little cover for its prey, and other land is cleared for farms and settlements
The source sayshabitat loss is still a huge problem for this species. Areas that are over-grazed leave little cover for prey animals ... Other areas are being cleared for human settlements and agricultural fields
The page saysA young secretarybird can fall prey to owls or ravens, but an adult is rarely hunted by anything
The source saysYoung Secretarybirds can fall prey to other predators such as owls and ravens, but adults are rarely preyed upon.
The page saysthey are the only members of their own family, Sagittariidae
The source saysthey are the one and only member of the family Sagittariidae

Source
02

San Diego Zoo Wildlife Alliance

Secretary Bird. San Diego Zoo Wildlife Alliance.

The page saysstanding 1.2 to 1.5 meters (4.1 to 4.9 feet) tall
The source saysHeight: 4.1 to 4.9 feet (1.2 to 1.5 meters) tallNote: SDZWA gives height; Peregrine's 1.2-1.5 m is body length
The page saysa wingspan around 2.1 meters (6.9 feet)
The source saysWIngspan: 6.9 feet (2.1 meters)Note: Peregrine gives 7 feet (2 m); 'around' covers both
The page saysIt can live 10 to 15 years, and up to 19 in a zoo
The source saysLIFE SPAN 10 to 15 years; up to 19 years in zoos
The page saysIts feet are built for walking, with little grip, and it hunts on foot
The source sayshunting for their food on foot ... The secretary bird's feet are adapted for walking and lack significant grasping ability.
The page saysA venomous snake may bite at its flapping feathers, but they make safe targets, because a bite to a hollow feather does not hurt the bird at all
The source saysA venomous snake might try to bite the secretary bird’s flapping feathers, but they serve as safe distractions or targets, since a bite to a hollow feather wouldn’t hurt the bird at all!
The page saysthen roosts high in an acacia tree at night
The source sayssecretary birds are good fliers and nest and roost high up in acacia trees at night
The page saysDistantly
The source saysSecretary birds are distantly related to buzzards, vultures, harriers, and kites.
The page saysThey are related to buzzards, vultures, harriers and kites
The source saysSecretary birds are distantly related to buzzards, vultures, harriers, and kites.
The page saysUnlike those raptor cousins, they spend most of their time on the ground
The source saysBut unlike their raptor cousins, secretary birds spend most of their time on the ground.

Source
03

Animal Diversity Web, University of Michigan

Sagittarius serpentarius. Animal Diversity Web, University of Michigan.

The page saysFrom Grasshoppers to Cobras
The source saysarthropods (including grasshoppers ... the snakes taken as prey are often adders, cobras, and other venomous species
The page saysSmall prey it simply catches in its bill
The source saysWith small prey, the bird will merely bend down and capture it in its bill.
The page saysIts menu runs from grasshoppers, beetles and scorpions to mice, hares, small birds, lizards and small tortoises, plus snakes, often adders and cobras
The source saysarthropods (including grasshoppers, beetles, spiders, scorpions, wasps, etc.) and small mammals (including mice, rats, hedgehogs, hares, mongooses, etc.) ... small and young birds, eggs, amphibians, freshwater crabs, lizards, small tortoises, chameleons and snakes ... the snakes taken as prey are often adders, cobras, and other venomous species
The page sayssnakes make up a smaller share of its diet than its reputation suggests
The source saysAlthough this species is famed for killing and eating snakes, these reptiles are not eaten as often as is generally believed.
The page saysA Raptor That Would Rather Walk
The source saysSecretary birds prefer to walk rather than fly
The page saysA secretarybird flies well, often at great heights, but it would rather walk
The source saysSecretary birds prefer to walk rather than fly ... When they do fly, they fly well and often at great heights.
The page sayswalking at a steady pace and searching for movement
The source saysThe birds will set out across a grassy area at a steady pace searching for movement.
The page saysusually in a pair or family group, sometimes alone
The source saysis sometimes solitary, but is more often found in pairs or family groups
The page saysThe name may come from its crest feathers, which made these birds look like old-time secretaries with quill pens tucked behind their ears
The source saysThe origin of the common name may come from the fact that their crest feathers made these birds look like old-time secretaries who used to keep their quill pens tucked behind their ears.
The page saysThat explanation has been challenged, though
The source saysIn recent years, however, this has been challenged.Note: ADW is dated 2007; SDZWA (current) also says the quill story 'was once thought'
The page sayssome think the name instead comes from the Arabic 'saqr et-tair', which might mean 'hunter bird'
The source saysIt is instead thought by some that the name comes from the Arabic 'saqr et-tair'. 'Saqr' means "hunter" or "hawk" and 'et-tair' means "flight" or, in general, "bird". Thus, 'saqr et-tair' might mean "hunter bird"
The page saysOpen savannas, grasslands, and semi-arid plains of sub-Saharan Africa
The source saysis found throughout Africa south of the Sahara ... Secretary birds prefer open savannahs and grasslands, although they also live in semi-desertsNote: 'semi-arid plains' for 'semi-deserts'
The page saysGrasshoppers, beetles, rodents, lizards, small tortoises, and snakes such as adders and cobras
The source saysarthropods (including grasshoppers, beetles, spiders, scorpions, wasps, etc.) and small mammals (including mice, rats, hedgehogs, hares, mongooses, etc.) ... lizards, small tortoises, chameleons and snakes ... the snakes taken as prey are often adders, cobras, and other venomous speciesNote: 'rodents' for mice and rats; a category list, not an exclusivity claim

Source
04

Portugal et al. 2016

Portugal et al. (2016). The fast and forceful kicking strike of the secretary bird. Current Biology.

The page saysThe stilt-legged snake executioner whose stomp, measured in one captive male, peaked at five times his body weight on average
The source saysthe peak force demands of secretary bird kicking strikes are remarkably high (Figure 1C), averaging 5.1 ± 0.9 body weights (195 ± 34 N, mean ± s.d.)Note: 195 N is the mean of the peak forces, not one kick. One captive male: the Royal Holloway release says the study 'focuses on a captive male Secretary Bird called Madeleine'
The page saysStomping kicks: one captive male's peak force averaged five times his body weight, his foot on the snake for about 15 milliseconds a strike
The source saysaveraging 5.1 ± 0.9 body weights (195 ± 34 N, mean ± s.d.) ... lasting only 15 ± 4.4 ms duration in contact
The page saysHis kicks peaked at an average of 195 newtons, equal to five times his own body weight, and his foot touched the snake for an average of just 15 milliseconds
The source saysaveraging 5.1 ± 0.9 body weights (195 ± 34 N, mean ± s.d.) ... lasting only 15 ± 4.4 ms duration in contact
The page saysA secretarybird often kills by kicking and stamping on its prey's head until the animal is stunned or dead, especially a larger lizard or a venomous snake
The source saysThey frequently kick and stamp on the prey's head until it is killed or incapacitated, particularly when dispatching larger lizards and venomous snakes
The page saysHis kicks peaked at 195 newtons on average, about five times his own body weight
The source saysaveraging 5.1 ± 0.9 body weights (195 ± 34 N, mean ± s.d.)

Source
05

Royal Holloway, University of London (via Phys.org) 2016

Snake-hunting secretary birds use the force of five times their body weight to stamp on and kill their prey. Royal Holloway, University of London (via Phys.org), 2016.

The page saysTo measure its kick, researchers pulled a rubber snake across a force plate hidden under artificial grass in the enclosure of Madeleine, a captive male trained to attack it
The source saysa captive male Secretary Bird called Madeleine ... Madeleine was trained to attack a rubber snake ... The scientists measured Madeleine's kicks by putting a force plate (hidden under artificial grass) in the bird's enclosure and pulling the rubber snake across the force plate.
The page saysA Tenth of a Blink
The source saysThe exceptionally rapid strike contact duration is 1/10th of the time it takes to blink an eye
The page saysMadeleine's foot stayed on the snake for about a tenth of the time it takes to blink, which lasts around 150 milliseconds
The source saysThe exceptionally rapid strike contact duration is 1/10th of the time it takes to blink an eye – which takes around 150 ms.Note: the blink duration is the researcher's comparison figure, not a bird figure
The page saysThe researchers concluded that a contact that brief, on legs that long, is too fast to steer by feel, so the bird aims by eye and plans each kick in advance
The source saysSuch rapid time, coupled with the exceptionally long legs, means the birds can't be using proprioreception – the sixth sense we use to sense our position and movement. Therefore, they are using visual targeting and feed-forward motor control – (pre-planned movements)Note: 'steer by feel' is proprioception, 'the sense we use to sense our position and movement'
The page saysOnce a kick starts it can't be adjusted, so a miss can only be corrected with the next one
The source saysthe birds can only correct for a missed strike in the next kick – once they've started a kick, they can't adapt it
The page saysIn a study at the Hawk Conservancy Trust, researchers measured a captive male secretarybird named Madeleine attacking a rubber snake pulled across a hidden force plate
The source saysfocuses on a captive male Secretary Bird called Madeleine, held at the Hawk Conservancy Trust, Hampshire. Madeleine was trained to attack a rubber snake ... The scientists measured Madeleine's kicks by putting a force plate (hidden under artificial grass) in the bird's enclosure and pulling the rubber snake across the force plate.
The page sayshis foot touched the snake for an average of just 15 milliseconds
The source saysthe contact time between the bird's feet and the snake is delivered extremely quickly - on average just 15 milliseconds
The page saysroughly a tenth of the time it takes to blink, which lasts around 150 milliseconds
The source saysThe exceptionally rapid strike contact duration is 1/10th of the time it takes to blink an eye – which takes around 150 ms.
The page saysThe researchers concluded that a contact that brief, on legs that long, has to be aimed by eye and planned in advance, so a miss can only be corrected with the next kick
The source saysSuch rapid time, coupled with the exceptionally long legs, means the birds can't be using proprioreception ... Therefore, they are using visual targeting and feed-forward motor control – (pre-planned movements) - during strike events. This means the birds can only correct for a missed strike in the next kick
The page saysmatching a stomp whose measured contact with the snake lasted 15 milliseconds on average
The source saysthe contact time between the bird's feet and the snake is delivered extremely quickly - on average just 15 millisecondsNote: the measured stomps are Madeleine's, the one captive male in the study

Source
06

The IUCN Red List of Threatened Species 2020

Sagittarius serpentarius. The IUCN Red List of Threatened Species 2020: e.T22696221A173647556.

The page saysThe IUCN lists the secretarybird as Endangered
The source saysIUCN Red List category: Endangered (EN).

How the table was made: a writer drafted the profile from these sources and logged each claim with its quote, a reviewer with nothing but this table checked every sentence said no more than its quote, and a script confirmed each quote appears word for word in the source. The method is in the site'sAbout page.