---
title: "What the sources say about the Harris's Hawk | AnimalTracks.wiki"
description: "41 claims from the Harris's Hawk profile, each beside the words of the source that backs it."
image: "https://animaltracks.wiki/images/animals/harris-hawk-1.webp"
canonical: "https://animaltracks.wiki/animals/harris-hawk/sources/"
---

# What the sources say about the Harris's Hawk (*Parabuteo unicinctus*)

> 41 claims from the Harris's Hawk profile, each beside the words of the source that backs it. A "..." marks a cut in a quote and [brackets] an insertion.

Profile: [Harris's Hawk](https://animaltracks.wiki/animals/harris-hawk/)

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

https://doi.org/10.1126/science.239.4847.1525

| The page says | The source says |
| :--- | :--- |
| In 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 | Coordinated 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.) |
| His Harris's hawks (Parabuteo unicinctus) in New Mexico broke the pattern. | documented convincingly only for a few mammalian carnivores. In New Mexico, Harris' hawks formed hunting parties (note: 'broke the pattern' restates the abstract's contrast: coordinated hunting had been shown only in a few mammalian carnivores, and these are birds.) |
| In the nonbreeding season they formed hunting parties of two to six birds | In New Mexico, Harris' hawks formed hunting parties of two to six individuals in the nonbreeding season. |
| which improved their capture success and let them kill prey larger than themselves | This behavior improved capture success and the average energy available per individual enabled hawks to dispatch prey larger than themselves. |
| James Bednarz found that in New Mexico, in the nonbreeding season, Harris's hawks formed hunting parties of two to six birds. | In New Mexico, Harris' hawks formed hunting parties of two to six individuals in the nonbreeding season. |
| Hunting together improved their capture success and the average energy available to each bird, and it let them kill prey larger than themselves. | This behavior improved capture success and the average energy available per individual enabled hawks to dispatch prey larger than themselves. |
| Cooperative pack-hunting tactics | Harris' hawks formed hunting parties of two to six individuals ... This behavior improved capture success |

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

https://doi.org/10.2173/bow.hrshaw.01

| The page says | The source says |
| :--- | :--- |
| Group 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. | group 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.) |
| A Harris's hawk hunting party chases fleeing prey by leap-frogging past one another as it dodges | group members will chase prey in open environments by leap-frogging past one another as prey evades successive attacks (note: vibe.reason, re-paired in wave 114 (screenshot test: the Spice Girls pairing mapped the artist's gender onto the alpha female).) |

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

https://doi.org/10.1038/s41467-019-10454-z

| The page says | The source says |
| :--- | :--- |
| When Oxford researchers filmed five captive-bred Harris's hawks chasing a lure towed around a zigzagging course | flight 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 birds steered with a mix of two rules. | Harris' Hawks use a mixed guidance law, coupling low-gain proportional navigation with a low-gain proportional pursuit element. |
| One 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. | Harris' 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 missiles (note: The source's own sentence opens 'In level flight, Peregrine Falcons...', which is where the page's 'in level flight' comes from.) |
| The 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. | Falcons 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. |

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

https://doi.org/10.1038/s41586-022-04861-4

| The page says | The source says |
| :--- | :--- |
| In 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 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 flights (note: '2022' is the reference's year.) |
| With a swoop. A 2022 study filmed four captive-bred Harris's hawks across 1,585 flights between perches. | 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 flights (note: '2022' is the reference's year.) |
| Each 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 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 |

## 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.

https://doi.org/10.1098/rspb.2018.1036

| The page says | The source says |
| :--- | :--- |
| 21.6 Cycles a Degree | The spatial resolution for isoluminant red-green gratings was 21.6 c deg -1 |
| In 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 | Using 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.) |
| though below the 62.3 their black-and-white vision reached | The 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 |
| A 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. | Using 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 -1 (note: '2018' is the reference's year.) |
| That 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. | -lower than that of the achromatic channel, but the highest found in the animal kingdom to date. |
| the highest colour-vision resolution measured in any animal to date | 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: Kept to the paper's measure (spatial resolution of the chromatic channel), not colour vision in general.) |

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

https://doi.org/10.1242/jeb.142083

| The page says | The source says |
| :--- | :--- |
| Each eye also has two foveas, one central and one temporal, where the black kite, a mostly carrion-eating raptor, has only one central fovea | Black 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. |

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

https://animaldiversity.org/accounts/Parabuteo_unicinctus/

| The page says | The source says |
| :--- | :--- |
| with a wingspan of 100 to 120 centimetres | have wingspans of 40 to 47 inches (100 to 120 cm) |
| the female is the bigger sex, averaging 1,047 grams against a male's 735 | Females 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.) |
| They live in semi-open country from the southwestern United States and northwestern Mexico south through Central and South America to Chile | Harris' 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. |
| In the Colorado River valley they range from saguaro desert to mesquite, palo verde and ironwood woodland | 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. |
| Whichever hawk makes the catch mantles it, spreading its wings over the kill to hide it from other birds | Another 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. |
| Groups 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 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. |
| All members help protect the nest. | All members of the group help with obtaining food, defending the breeding territory, and providing nest protection. |
| Great horned owls are the greatest predation threat, and coyotes and common ravens also threaten young hawks. | Great 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. |
| Groups 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. | Groups 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. |
| By 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. | There 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. |
| Mostly rats and mice, plus birds, lizards, cottontails, and jackrabbits caught by hunting parties | These 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. |
| Semi-open desert, savanna and scrub, from saguaro desert to mesquite woodland | Harris' 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'.) |
| matriarchal | The 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.) |
| family packs | Often 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.) |
| dangerLevel: Low | The 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".) |

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

https://www.audubon.org/field-guide/bird/harriss-hawk

| The page says | The source says |
| :--- | :--- |
| Harris's hawks measure 46 to 61 centimetres long | Length: 18 in-2 ft (46-61 cm) (note: Replaces ADW's self-contradictory 18 to 23 inches (46 to 76 cm).) |

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

https://genomics.senescence.info/species/entry.php?species=Parabuteo_unicinctus

| The page says | The source says |
| :--- | :--- |
| The longevity record in captivity is 25 years | Maximum 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.) |

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

https://doi.org/10.2305/iucn.uk.2024-2.rlts.t22695838a264594685.en

| The page says | The source says |
| :--- | :--- |
| Least Concern | IUCN 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.) |