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Harris’ Hawk: Parabuteo unicinctus
In the Wild
Description:
Size:
o Medium-large hawk with a long tail and broad wings
o Length: 18-23 inches (46-76 cm)
o Wingspan: 40-47 inches (100-120 cm)
Weight:
o Female: Average of 2.3 lbs. (1,047 grams)
o Male: Average of 1.6 lbs. (735 grams)
Sexual dimorphism: Females are generally larger than males
Coloration
o Adults are uniformly chocolate-brown with distinct reddish shoulders and a
white rump patch and tail tip
o Juveniles are similar to adults but coloring is less distinct and have white bellies
with brown streaking
Habitat and Range:
Found in a variety of habitats, but mainly semi-open, highland, desert habitats
Range includes the southwestern United States and northwest Mexico, and extends
south through Central and South America to Chile
Diet:
Carnivore: Eat rats, mice, birds, lizards, cottontails and jack rabbits
Hunting technique:
o Commonly hunt in groups of about 5 hawks, increasing their success rate and
enabling them to take larger prey such as cottontails or jack rabbits
o If there is no underbrush in which prey may hide, several hawks may pounce on
the prey
o If there is cover for prey to hide in, 1 hawk may scare or flush prey out while
other group members are ready to capture it
o If the prey runs away, the hawks may take turns chasing and wearing out the
prey until it hides in underbrush – they then land and take turns trying to scare
them out of their hiding place
o If a member of the hunting group captures the prey, it assumes a posture known
as mantling, where it guards the prey from other predators using its wings – the
group can guard prey for more than a day from other predators, a form of
storing food
o It has been suggested that group hunting is encouraged by the dense brush and
thorny nature of parts of their range
Adaptations:
Rely upon excellent eyesight and keen hearing for spotting prey
Heavy eyebrows keep sun out of their eyes while searching for prey
07/28/2013
The Maryland Zoo in Baltimore
Harris’ Hawk: Parabuteo unicinctus
Have a strong, hooked beak and powerful talons for catching prey
Long, paddle-like wings make Harris’ hawks agile fliers – can easily maneuver through
brush and tail other birds
While flying, the long, narrow outer wing feathers separate into “fingers” which allow
Harris’ hawks to slow down without stalling
Unlike most birds of prey, often form complex social groups
o All members of the group help with obtaining food, defending the breeding
territory and providing nest protection
o Also sometimes hunt cooperatively which increases survival rates
o Establish and defend large territories (range from 0.2-5.5 square kilometers) –
territory size depends on the availability of food and other resources
Lifespan:
Highest recorded age of 14 years 11 months
Ecosystem relationships:
Predators: Great horned owls pose the greatest predation threat to this species, but
coyotes and common ravens also threaten young hawks
Female Harris’ hawks utilize helpers to protect their nests
o The helpers perch and scan the surroundings for predators
o They use an alarm call when predators come within the nesting area
o Groups consisting of 2-5 hawks will attack and harass any predator threatening
the nest
o The alpha male is most likely to strike the predator as the female stays behind to
protect the nest
o This establishment of helpers greatly increases the detection of predators and
therefore increases nest success
Are important predators in their ecosystem, controlling populations of many small
mammal species
Reproduction:
Most often, a group of Harris’ hawks contains a single monogamous breeding pair
Sometimes females may be polyandrous – they may have more than one mate
o Form a trio with 2 males breeding with 1 female
o The female and her mates all care for the young
o Polyandry is commonly found in areas where the habitat quality is rich as
opposed to arid habitats where the chances of reproductive success are less,
even when there are 3 adults hunting
o Also common in Arizona where the sex ratio is significantly skewed towards
males, in comparison with areas such as Texas, where the sex ratio is not as
skewed
Aerial displays are an important part of courtship – males dive vertically for several
hundred feet and then land near or on the back of the female
07/28/2013
The Maryland Zoo in Baltimore
Harris’ Hawk: Parabuteo unicinctus
Nests are built in cacti or trees, 8-30 feet aboveground
Nests are made of sticks, twigs, mesquite and yucca
Females have the ability to breed all year long and can lay 2-3 clutches within a year
Each clutch includes 2-4 eggs
Incubation lasts about a month
o Both males and females incubate the eggs
o Other birds, including recently fledged juveniles as well as adults, often assist in
raising the young
Hatchlings fledge after about a month and a half
The young remain in the nest area 2-3 months after hatching
Activity:
Diurnal: Generally hunt in early morning and evening hours
Non-migratory: Usually remain in the same area year round
Other “fun facts”:
The Harris’ hawk was named after Edward Harris, a friend of John J. Audubon
Are sometimes nicknamed “wolves of the sky” because of their tendency to hunt in a
group
Exhibit an unusual behavior called "stacking" where one individual will perch on a cactus
and 2-3 additional birds will stand on top of its back – with a shortage of tall trees in
their habitat, this behavior helps them to better see prey and predators
Are one of the most popular hawks for falconry – as a result, escapees are sometimes
spotted in Great Britain
Conservation Status and Threats:
Listed on the IUCN Red List as Least Concern – although this species has an extremely
large range, populations appears to be decreasing and they are rare in parts of their
range
Listed under CITES Appendix II
Are protected from harassment and illegal shooting by the Migratory Bird Treaty Act
Populations are thought to be affected by:
o Habitat loss – the major cause of decline of this species
 Populations had decreased dramatically in California after development
projects resulted in severe habitat loss
By the 1950s, they nearly vanished from California
In 1979, the Santa Cruz Predatory Bird Research Group began to
reintroduce Harris’ hawks into the state
 Real estate and agriculture threaten the species in Arizona
 Recent declines in Texas populations resulted from the clearing of
mesquite for agriculture and livestock grazing
07/28/2013
The Maryland Zoo in Baltimore
Harris’ Hawk: Parabuteo unicinctus

A population on the Colorado River was extirpated due to habitat
disturbance from dam construction, dredging and nest destruction –
theses disturbances can cause parents to abandon their nests
o Tend to congregate on electrical transformers, where they are often
electrocuted – electric companies are re-insulating or building arms for perching
to reduce mortality rates
A reintroduction program took place from 1979-1989 in the lower Colorado River valley
o Almost 200 individuals were released to the area
o There was initial success with 5 pairs raising offspring – the restoration effort did
not coincide with habitat restoration, however, and long-term survival of the
population is unlikely
At the Zoo
Cactus was born at a breeding facility in 2004 and acquired by the zoo the same year. She
weighs 2 lbs. (900 grams).
What We Can Do
Make environmentally responsible lifestyle decisions to help conserve habitat –
conserve energy, reduce litter and pollution
Harris’ hawks can be found in agricultural and suburban areas in the Southwest United
States so residents in that area should be aware of their existence and try not to disturb
any hawks living around their home/neighborhood – they are not aggressive and can
keep rodent populations in check
References:
http://animaldiversity.ummz.umich.edu/accounts/Parabuteo_unicinctus/
http://www.oregonzoo.org/discover/animals/harris-hawk
http://www.iucnredlist.org/details/106003492/0
http://www.zoo.org/page.aspx?pid=1848
http://audubon2.org/watchlist/viewSpecies.jsp?id=106
http://www.bbc.co.uk/nature/life/Harris's_Hawk
http://www.torontozoo.com/explorethezoo/AnimalDetails.asp?pg=705
07/28/2013
The Maryland Zoo in Baltimore