The Harris’s hawk (Parabuteo unicinctus), formerly known as the bay-winged hawk or dusky hawk, is a medium-large bird of prey that breeds from the southwestern United States south to Chile, central Argentina, and Brazil.
Quick Facts on the Harris Hawk
- Scientific Name: Parabuteo unicinctus
- Average Length: 18-25 inches
- Average Wingspan: 3.5-4.5 feet
- Average Weight: 1.5-2.5 pounds
- Lifespan in the Wild: 12 years
- Conservation Status: Least Concern
The Harris’s hawk is notable for its behavior of hunting cooperatively in groups of two to six. This is rare among raptors, with only a very few other known examples such as the Galapagos hawk. This social behavior brings benefits such as minimizing energy expenditure, enabling the use of specific techniques, and making predators more efficient.
Description and Identification
The Harris’s hawk has dark reddish brown upperparts and white underparts with reddish streaking. The long tail stripes are a distinguishing characteristic. The legs are yellow and very long in proportion to the body. The Harris’s hawk has a longer wing, shorter tail, and flies differently from the other North American buteos.
| Characteristic | Description |
|---|---|
| Size | 18-25 inches long with a 3.5-4.5 foot wingspan |
| Weight | 1.5-2.5 pounds |
| Coloring | Dark reddish brown upperparts, white underparts with reddish streaking |
| Distinguishing Features | Long tail stripes, long yellow legs, different wing and tail proportions compared to other buteos |
Habitat and Range
The Harris’s hawk is found in the arid to semiarid regions of the Americas. Its range stretches from the southwestern United States south through Mexico and Central America. It is also found in South America in Chile, Argentina, Paraguay, and Brazil.
Within their range, Harris’s hawks occupy habitats including desert, scrubland, savanna, grassland, farmland, and semi-open country with scattered trees. They avoid dense forests. Harris’s hawks require some trees or other elevated perches in their habitat for hunting and nesting. Their range overlaps broadly with that of the cactus wren, a preferred prey item.
Diet and Hunting
Harris’s hawks are opportunistic predators and eat a wide variety of small animals. Common prey items include mammals like rabbits, ground squirrels, rats, mice, and prairie dogs. They also eat reptiles such as snakes and lizards. Birds are another major part of their diet – typical avian prey includes doves, quail, roadrunners, woodpeckers, coots, pheasants and smaller raptors. Harris’s hawks have adapted their hunting techniques to take advantage of locally abundant prey.
| Prey Type | Specific Examples |
|---|---|
| Mammals | Rabbits, ground squirrels, rats, mice, prairie dogs |
| Reptiles | Snakes, lizards |
| Birds | Doves, quail, roadrunners, woodpeckers, coots, pheasants, smaller raptors |
Harris’s hawks often hunt cooperatively in groups, which gives them an advantage in pursuing and capturing prey. With coordinated efforts, they are able to take down larger prey. Harris’s hawks use a wide variety of hunting techniques including short rapid flights, chasing prey on foot, ambushing prey from perches, cooperative drives of prey, and more.
Unique Behavior and Adaptations
The Harris’s hawk exhibits some very unique and fascinating behaviors among birds of prey. Their social nature sets them apart from most raptors.
Cooperative Hunting
The most distinctive behavior of the Harris’s hawk is their social, coordinated hunting. They most often hunt in loose groups of 2-6 birds, though larger aggregations around carrion have been observed. This cooperative hunting brings many benefits:
- Minimizes energy expenditure by reducing time in flight and chasing
- Enables capture of larger prey through group tactics
- Increases hunting success rate
- Allows for division of labor by role
- Distributes risk of injury to individuals
When beginning a hunt, the hawks position themselves around their prey – some acting as flushers while others wait to ambush. They take cues from one another’s movements. One example tactic is a rapid series of relay attacks, where the hawks take turns swooping in to harass the prey. The coordinated harassment can tire out and corner the prey until captured.
Role Specialization
Research has identified four distinct cooperative hunting roles among Harris’s hawks:
| Role | Description |
|---|---|
| Flushers | Initiate an attack to startle and get prey moving |
| Chasers | Pursue fleeing prey |
| Blockers | Take up positions to ambush cornered prey |
| Capturers | Try to contain and capture prey |
Individual hawks tend to specialize in a particular role during hunts based on their age, experience and personal dispositions. Cooperation and role division optimizes the group’s chance for a successful hunt.
Vocal Communication
Harris’s hawks use vocalizations to communicate and coordinate during hunts. Some examples:
- Loud “kleeers” – indicate prey has been spotted
- “Beducks” – flushers are starting an attack
- Whistling – chasers keep track of prey location
- Yelps – hunger calls communicate readiness to hunt
Research found identifiable individual voices in Cooper’s hawk calls, suggesting they may be able to distinguish each other by voice as well. Vocal communication facilitates their sophisticated group strategy.
Flexible Social Structure
Harris’s hawks show a flexible social organization. In areas with high prey density, larger groups form with a dominance hierarchy. Where prey is more scarce, they live in smaller groups with a monogamous mated pair.
Social behaviors include:
- Allopreening – Hawks groom one another
- Food sharing – Hawks sometimes share food within the group
- Cooperative breeding – Extra birds help raise offspring
Their adaptable social structure seems to be an evolutionary advantage. The hawks can alter their organization and behaviors to best fit local conditions.
Reproduction and Nesting
The breeding season of Harris’s hawks depends on their geographic location:
- Northern populations: February to July
- Southern populations: July to December
Courtship displays include aerial maneuvers and vocalizations. The hawks mate for life once a pair bond has formed. Harris’s hawks build bulky stick nests lined with leaves, twigs, and bark. Nest locations are most often in trees such as palo verde, cottonwood, and saguaro cactus, or on power poles and telephone towers.
| Harris’s Hawk Reproduction Facts |
|---|
| Clutch Size: 2-4 eggs |
| Incubation Period: 35 days |
| Fledging Period: 38-42 days |
| Broods per Year: 1 |
The female does most of the 34-35 days of incubation while the male provides food. Once hatched, both parents feed and care for the chicks. Young hawks fledge at 38-42 days old but remain dependent on their parents through the first winter. Most breeding pairs remain together for multiple years and may use the same nest repeatedly.
Population and Conservation
Harris’s hawks are classified as “Least Concern” on the IUCN Red List. Their total population is estimated at 1 million to 10 million individuals. Population densities can reach up to 36 nesting pairs in favorable habitat. Their range is very widespread across the Americas.
While Harris’s hawk populations remain healthy overall, local declines have occurred in some areas due to:
- Habitat loss and degradation
- Secondary poisoning from pesticides and rodenticides
- Shooting, trapping and hunting
- Electrocution on power lines
- Vehicle collisions
Ongoing conservation priorities include protecting areas of natural habitat and limiting the use of toxic chemicals. Their unique cooperative social behavior has made the Harris’s hawk a valued species for use in falconry as well – maintaining this traditional practice supports ongoing conservation.
Uses of Harris’s Hawks
Falconry
The Harris’s hawk is one of the most popular raptors used in the ancient sport of falconry. Their social nature means they work well in groups for falconry. Harris’s hawks are also easier to train and more comfortable with human proximity than many other falconry birds.
Attributes that make them well-suited to falconry:
- Intelligence – able to take direction and follow commands
- Cooperative hunting skills translate well
- Strength to pursue game like rabbits
- Friendly disposition and social nature
In falconry, Harris’s hawks are often used in coordinated groups by a handler to catch game. Their teamwork can make them highly effective hunters alongside humans. Falconry provides exercise and mental stimulation for captive birds.
Research
The unique cooperative social behaviors of the Harris’s hawk make them an important species for scientific research. Ongoing studies investigate topics such as:
- Communication methods and vocalizations
- Hierarchy and social structure
- Hunting strategies and specializations
- Evolution of cooperative behavior
- Reasons for their social nature
- Comparison with other social and solitary raptors
- Development of roles and skills in young
Researchers can gain critical insights into avian intelligence, learning, communication and social behavior by studying this remarkable species. Findings could potentially apply to other birds and even species like wolves that demonstrate social hunting.
Pest Control
The hunting skills of Harris’s hawks have occasionally been put to use as natural pest control. On some agricultural lands, falconers have successfully used these birds to control rodents and rabbits.
Key advantages of Harris’s hawks for natural pest control:
- Take a wide variety of rodent prey species
- Cooperative hunting improves efficacy
- More trainable than owls also used for rodent control
- Don’t require poisons that can persist in ecosystem
However, even skilled Harris’s hawks do not replicate the precise results of traps and poisons. Chemicals remain the standard for large-scale rodent control. The pest control potential of Harris’s hawks is limited to small-scale specialty use in agricultural settings.
Conclusion
The Harris’s hawk is a fascinating bird of prey thanks to its highly social behavior and cooperative hunting. This unusual adaptation allows them to effectively pursue agile prey across the deserts and scrublands of the Americas. Their distinctive characteristics make them ideal for use in the traditional sport of falconry. Continued research on Harris’s hawks can provide biological insights that may be applicable well beyond just one bird species. While overall a common and widespread bird not vulnerable to extinction, maintaining populations of the Harris’s hawk helps preserve an iconic, unique and important part of desert ecosystems.
