The desert ecosystem requires its inhabitants to be exceptionally resilient. Hawks like the Red-tailed Hawk and Harris’s Hawk are mid-level predators, soaring above the arid scrubland to hunt rodents, reptiles, and other small prey. These raptors possess formidable talons and keen eyesight, placing them high on the food web. Despite their dominance, these birds are not without natural threats, particularly from larger competitors and opportunistic carnivores.
Apex Predators Targeting Adult Hawks
The most significant threat to a fully grown desert hawk comes from other large raptors, especially those that hunt at night. The Great Horned Owl (Bubo virginianus) is the primary predator of adult hawks, including the Red-tailed Hawk. Its nocturnal habits allow it to silently ambush a diurnal hawk on its roosting perch under the cover of darkness.
An adult Great Horned Owl can outweigh a Red-tailed Hawk by as much as 30% and possesses greater crushing power in its talons. This size difference often allows the owl to subdue and kill a hawk, making it the most prolific predator of other raptors. Golden Eagles, being larger and more powerful, may also pose a threat, particularly in territorial conflicts over hunting grounds.
Predation on a healthy, flying adult hawk is rare, but terrestrial carnivores take advantage of grounded or injured birds. Coyotes, bobcats, and large foxes are capable of killing a hawk if it is caught on the ground or distracted while feeding. These mammals typically target raptors that are already weakened or surprised.
Threats to Eggs and Nestlings
The majority of hawk mortality occurs during the vulnerable nesting phase, targeting eggs and chicks. Desert hawk nests, often built in exposed locations, are accessible to various predators. The Great Horned Owl actively raids hawk nests to prey on nestlings and may even displace the parents to usurp the nest site.
Crows and Common Ravens (corvids) are highly intelligent and opportunistic predators of hawk eggs and nestlings. These birds often work in groups, with some distracting the parents while others raid the nest.
Terrestrial predators also pose a significant threat, especially if the nest is built at a lower elevation:
- Raccoons
- Foxes
- Ringtails
- Snakes, such as desert rattlesnakes or Gopher Snakes, which climb to consume eggs and young chicks.
The vulnerability of the young is compounded by their immobility, making the nesting period the highest risk time for a hawk’s life cycle.
Environmental Factors Affecting Hawk Survival
Beyond direct predation, desert hawks face numerous non-biological threats that contribute to mortality. The harsh desert climate is a continuous stressor, with extreme heat and prolonged drought leading to reductions in available prey. When small mammals become scarce, hawks can suffer from starvation, particularly inexperienced juveniles.
Human infrastructure also presents a major cause of death. Electrocution is common when hawks perch on power poles with inadequate insulation. Collisions with vehicles or windows in urbanized areas are also frequently documented causes of fatality.
Disease and parasites limit hawk survival. Fungal infections, such as Aspergillosis, can be fatal. Internal injuries caused by swallowing sharp bones from prey can lead to perforation and death. These factors often weaken the birds, making them more susceptible to other forms of mortality.