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What the sources say

Harris's HawkParabuteo unicinctus

Every figure, record and mechanism on the Harris's Hawk profile was written from a source, and this is the working table behind it: 41 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.

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Source
01

Bednarz 1988

Bednarz (1988). Cooperative Hunting Harris' Hawks (Parabuteo unicinctus). Science.

The page saysIn a 1988 paper, biologist James Bednarz noted that coordinated hunting aimed at catching and sharing one large prey animal had been convincingly documented only in a few mammal carnivores
The source saysCoordinated hunting by several individuals directed toward the capture and sharing of one Large prey animal has been documented convincingly only for a few mammalian carnivores.Note: '1988' and 'Bednarz' are the reference's own year and author field (Science, 1988), not text inside the quote.
The page saysHis Harris's hawks (Parabuteo unicinctus) in New Mexico broke the pattern.
The source saysdocumented convincingly only for a few mammalian carnivores. In New Mexico, Harris' hawks formed hunting partiesNote: 'broke the pattern' restates the abstract's contrast: coordinated hunting had been shown only in a few mammalian carnivores, and these are birds.
The page saysIn the nonbreeding season they formed hunting parties of two to six birds
The source saysIn New Mexico, Harris' hawks formed hunting parties of two to six individuals in the nonbreeding season.
The page sayswhich improved their capture success and let them kill prey larger than themselves
The source saysThis behavior improved capture success and the average energy available per individual enabled hawks to dispatch prey larger than themselves.
The page saysJames Bednarz found that in New Mexico, in the nonbreeding season, Harris's hawks formed hunting parties of two to six birds.
The source saysIn New Mexico, Harris' hawks formed hunting parties of two to six individuals in the nonbreeding season.
The page saysHunting together improved their capture success and the average energy available to each bird, and it let them kill prey larger than themselves.
The source saysThis behavior improved capture success and the average energy available per individual enabled hawks to dispatch prey larger than themselves.
The page saysCooperative pack-hunting tactics
The source saysHarris' hawks formed hunting parties of two to six individuals ... This behavior improved capture success

Source
02

Dwyer & Bednarz 2020

Dwyer & Bednarz (2020). Harris's Hawk (Parabuteo unicinctus). Birds of the World.

The page saysGroup members chase fleeing prey across open ground by leap-frogging past one another as it dodges, converge on it from several directions at once to cut off its escape, or surround a hiding spot while one hawk walks in on foot to flush the animal out for the others to catch.
The source saysgroup members will chase prey in open environments by leap-frogging past one another as prey evades successive attacks, will simultaneously converge on fleeing prey from multiple directions to cut off escape, and will surround the hiding place of hidden prey while one bird approaches on foot to flush their quarry so group mates may capture it.Note: 'for the others to catch' renders the source's purpose clause 'so group mates may capture it'; the 'may' is about the purpose of flushing, not whether the tactic happens.
The page saysA Harris's hawk hunting party chases fleeing prey by leap-frogging past one another as it dodges
The source saysgroup members will chase prey in open environments by leap-frogging past one another as prey evades successive attacksNote: vibe.reason, re-paired in wave 114 (screenshot test: the Spice Girls pairing mapped the artist's gender onto the alpha female).

Source
03

Brighton & Taylor 2019

Brighton & Taylor (2019). Hawks steer attacks using a guidance system tuned for close pursuit of erratically manoeuvring targets. Nature Communications.

The page saysWhen Oxford researchers filmed five captive-bred Harris's hawks chasing a lure towed around a zigzagging course
The source saysflight trajectories of n = 5 captive-bred Harris' Hawks Parabuteo unicinctus ... Five captive Harris' Hawks chased a lure pulled at speed around a randomised zigzagging course of pulleys and tunnels.Note: 'Oxford' is the authors' affiliation in the paper's header: 'Department of Zoology, University of Oxford'. 'filmed' renders 'four high-speed cameras recording at 250 Hz'.
The page saysthe birds steered with a mix of two rules.
The source saysHarris' Hawks use a mixed guidance law, coupling low-gain proportional navigation with a low-gain proportional pursuit element.
The page saysOne was a low-gain form of proportional navigation, the rule peregrine falcons in level flight share with homing missiles; the other was a pursuit element that promotes tail-chasing.
The source saysHarris' Hawks use a mixed guidance law, coupling low-gain proportional navigation with a low-gain proportional pursuit element. This guidance law promotes tail-chasing ... Peregrine Falcons Falco peregrinus have recently been shown to use the same proportional navigation guidance law as missilesNote: The source's own sentence opens 'In level flight, Peregrine Falcons...', which is where the page's 'in level flight' comes from.
The page saysThe researchers found the mix well suited to close pursuit of agile prey through clutter, while the falcons' missile-style guidance works well in the open.
The source saysFalcons intercept prey at high-speed using the same proportional navigation guidance law as homing missiles. This classical guidance law works well in the open ... making it well suited to the hawks' natural hunting style, involving close pursuit of agile prey through clutter.

Source
04

KleinHeerenbrink et al. 2022

KleinHeerenbrink et al. (2022). Optimization of avian perching manoeuvres. Nature.

The page saysIn a 2022 study, four captive-bred hawks filmed across 1,585 flights between perches swooped in a way that minimised neither time nor energy, but the distance they flew after stalling.
The source saysthe swooping trajectories of perching Harris' hawks ( Parabuteo unicinctus ) minimize neither time nor energy alone, but rather minimize the distance flown after stalling. ... we rigged a large custom-built motion capture studio to record n = 4 captive-bred Harris' hawks flying between perches for food ... We collected trajectory data from 1,585 flightsNote: '2022' is the reference's year.
The page saysWith a swoop. A 2022 study filmed four captive-bred Harris's hawks across 1,585 flights between perches.
The source sayswe rigged a large custom-built motion capture studio to record n = 4 captive-bred Harris' hawks flying between perches for food ... We collected trajectory data from 1,585 flightsNote: '2022' is the reference's year.
The page saysEach swoop began with a dive under several powerful wingbeats and turned into an unpowered climb, and where the birds switched from one to the other minimised the distance they flew after stalling, not their time or energy.
The source saysthe swooping trajectories of perching Harris' hawks ( Parabuteo unicinctus ) minimize neither time nor energy alone, but rather minimize the distance flown after stalling. ... we find that the birds' choice of where to transition from powered dive to unpowered climb minimizes the distance over which high lift coefficients are required. ... Swooping was initiated by jumping forward into a dive involving several powerful wingbeats, which transitioned into an unpowered climb finishing with a rapid pitch-up manoeuvre

Source
05

Potier, Mitkus & Kelber 2018

Potier, Mitkus & Kelber (2018). High resolution of colour vision, but low contrast sensitivity in a diurnal raptor. Proceedings of the Royal Society B: Biological Sciences.

The page says21.6 Cycles a Degree
The source saysThe spatial resolution for isoluminant red-green gratings was 21.6 c deg -1
The page saysIn a 2018 study, trained Harris's hawks resolved red and green stripes of equal brightness as fine as 21.6 cycles per degree, the highest resolution of colour vision found in the animal kingdom to date
The source saysUsing an operant conditioning method, we determined (i) the achromatic contrast sensitivity function and (ii) the spatial resolution of the chromatic channel of a diurnal raptor, the Harris's hawk Parabuteo unicinctus ... The spatial resolution for isoluminant red-green gratings was 21.6 c deg -1 -lower than that of the achromatic channel, but the highest found in the animal kingdom to date.Note: 'trained' renders 'operant conditioning'; 'stripes of equal brightness' renders 'isoluminant gratings'. The superlative is the paper's own and is kept to the one measure, the spatial resolution of the chromatic channel. '2018' is the reference's year.
The page saysthough below the 62.3 their black-and-white vision reached
The source saysThe maximal spatial resolution for achromatic gratings was 62.3 c deg -1 ... The spatial resolution for isoluminant red-green gratings was 21.6 c deg -1 -lower than that of the achromatic channel
The page saysA 2018 study trained Harris's hawks to resolve red and green stripes of equal brightness and measured a resolution of 21.6 cycles per degree.
The source saysUsing an operant conditioning method, we determined (i) the achromatic contrast sensitivity function and (ii) the spatial resolution of the chromatic channel ... The spatial resolution for isoluminant red-green gratings was 21.6 c deg -1Note: '2018' is the reference's year.
The page saysThat is lower than the hawk's own black-and-white resolution, but it is the highest colour-vision resolution found in the animal kingdom to date.
The source says-lower than that of the achromatic channel, but the highest found in the animal kingdom to date.
The page saysthe highest colour-vision resolution measured in any animal to date
The source saysThe spatial resolution for isoluminant red-green gratings was 21.6 c deg -1 -lower than that of the achromatic channel, but the highest found in the animal kingdom to date.Note: Kept to the paper's measure (spatial resolution of the chromatic channel), not colour vision in general.

Source
06

Potier et al. 2016

Potier et al. (2016). Visual abilities in two raptors with different ecology. Journal of Experimental Biology.

The page saysEach eye also has two foveas, one central and one temporal, where the black kite, a mostly carrion-eating raptor, has only one central fovea
The source saysBlack Kites Milvus migrans, which are primarily carrion eaters ... Harris's Hawks have two foveas (one central and one temporal) while Black Kites have only one central fovea and a temporal area.

Source
07

Truglio 2003

Truglio (2003). Parabuteo unicinctus (Harris's hawk). Animal Diversity Web, University of Michigan.

The page sayswith a wingspan of 100 to 120 centimetres
The source sayshave wingspans of 40 to 47 inches (100 to 120 cm)
The page saysthe female is the bigger sex, averaging 1,047 grams against a male's 735
The source saysFemales weigh an average of 1,047 grams, and males are smaller, weighing an average of 735 grams.Note: the sentence's own 'averaging' carries the hedge across both figures.
The page saysThey live in semi-open country from the southwestern United States and northwestern Mexico south through Central and South America to Chile
The source saysHarris' hawks can be found in semi-open habitats in the southwestern United States and northwestern Mexico, from Baja California to southern Arizona, New Mexico and Texas, extending south through Central and South America to Chile and just into Patagonia.
The page saysIn the Colorado River valley they range from saguaro desert to mesquite, palo verde and ironwood woodland
The source saysHarris' hawks are found in various habitats, from upland desert dominated by saguaros to mesquite, palo verde, and ironwood woodlands in the Colorado River valley.
The page saysWhichever hawk makes the catch mantles it, spreading its wings over the kill to hide it from other birds
The source saysAnother member of the hunting group captures the animal and assumes a posture known as mantling, in which the hawk shields the prey with its wings to hide it from other birds.
The page saysGroups form around an alpha female, dominant to every other hawk in the group, and an alpha male, dominant to the other males. Many also hold a beta male and "gamma" birds, usually immature and often the alpha pair's own young.
The source saysThe breeding, or alpha, female, is dominant to all other hawks in the group. ... The breeding, or alpha, male is dominant to all other males in the group. Commonly the group contains a beta male ... there may be several gamma birds, which are subordinate to the alpha and beta individuals. These gamma birds may be either male or female, and usually they are sexually immature individuals. Often they are the juvenile offspring of the alpha pair.
The page saysAll members help protect the nest.
The source saysAll members of the group help with obtaining food, defending the breeding territory, and providing nest protection.
The page saysGreat horned owls are the greatest predation threat, and coyotes and common ravens also threaten young hawks.
The source saysGreat horned owls (Bubo virginianus) pose the greatest predation threat to this species, but coyotes (Canis latrans) and common ravens (Corvus corax) also threaten young hawks.
The page saysGroups of two to five hawks will attack and harass a predator threatening the nest, with the alpha male most likely to strike it while the female stays behind.
The source saysGroups consisting of 2 to 5 hawks will attack and harass any predator threatening the nest. The alpha male is most likely to strike the predator as the female stays behind to protect the nest.
The page saysBy a strict dominance hierarchy. The alpha female is dominant to every other hawk in the group, and the alpha male to every other male. Many groups also include a beta male and 'gamma' birds, usually sexually immature and often the alpha pair's own young.
The source saysThere is a strict dominance hierarchy within groups of Harris' hawks. The breeding, or alpha, female, is dominant to all other hawks in the group. ... The breeding, or alpha, male is dominant to all other males in the group. Commonly the group contains a beta male ... there may be several gamma birds ... usually they are sexually immature individuals. Often they are the juvenile offspring of the alpha pair.
The page saysMostly rats and mice, plus birds, lizards, cottontails, and jackrabbits caught by hunting parties
The source saysThese hawks feed mostly on small mammals such as rats and mice, but also take birds and lizards. They commonly hunt in groups of about five hawks, increasing their success rate and enabling them to take larger prey such as cottontails and jack rabbits.
The page saysSemi-open desert, savanna and scrub, from saguaro desert to mesquite woodland
The source saysHarris' hawks can be found in semi-open habitats ... Harris' hawks are found in various habitats, from upland desert dominated by saguaros to mesquite, palo verde, and ironwood woodlands in the Colorado River valley.Note: 'desert, savanna and scrub' are ADW's own terrestrial biome tags for the species: 'desert or dune', 'savanna or grassland' and 'scrub forest'.
The page saysmatriarchal
The source saysThe breeding, or alpha, female, is dominant to all other hawks in the group.Note: Supports the tagline's 'matriarchal': the group's highest-ranked bird is the breeding female.
The page saysfamily packs
The source saysOften they are the juvenile offspring of the alpha pair. ... These hunting groups consist of a breeding pair and other helpers, with the female dominating.Note: Supports the tagline's 'family packs': ADW's hunting groups are a breeding pair plus helpers, often the pair's own young.
The page saysdangerLevel: Low
The source saysThe only negative impact of these hawks is their habit of congregating on electrical transformers, where they are often electrocuted.Note: Settles #836: no source describes harm to people; Birds of the World (harris-2020): "Harris's Hawks bond easily to human handlers".

Source
08

Audubon Guide to North American Birds, National Audubon Society

Harris's Hawk. Audubon Guide to North American Birds, National Audubon Society.

The page saysHarris's hawks measure 46 to 61 centimetres long
The source saysLength: 18 in-2 ft (46-61 cm)Note: Replaces ADW's self-contradictory 18 to 23 inches (46 to 76 cm).

Source
09

AnAge: The Animal Ageing and Longevity Database, Human Ageing Genomic Resources

AnAge entry for Parabuteo unicinctus. AnAge: The Animal Ageing and Longevity Database, Human Ageing Genomic Resources.

The page saysThe longevity record in captivity is 25 years
The source saysMaximum longevity 25 years (captivity)Note: AnAge build 15 (03/07/2023); confirmed the entry is for Parabuteo unicinctus, common name Harris's hawk. 'record' renders 'Maximum longevity'. Cited instead of ADW's 2003 wild-longevity record of 14 years 11 months.

Source
10

The IUCN Red List of Threatened Species 2024

Parabuteo unicinctus. The IUCN Red List of Threatened Species 2024: e.T22695838A264594685.

The page saysLeast Concern
The source saysIUCN Red List category: Least Concern (LC).Note: Read through GBIF's copy of the Red List, checked against IUCN taxon 22695838, the taxon id inside the assessment DOI (...t22695838a264594685...); iucnredlist.org itself refuses scripts.

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.