The broad-winged hawk (Buteo platypterus) is a medium-sized raptor found throughout much of North America. As with most bird species, broad-winged hawks face threats from predators throughout their lives. In this article, we’ll take an in-depth look at the natural predators that broad-winged hawks must watch out for at different stages of life.
Nestlings and Fledglings
Broad-winged hawks build nests high up in deciduous and mixed forests, typically 20-60 feet above ground. The female lays 1-3 eggs which hatch after about 35 days of incubation. For the first few weeks after hatching, broad-winged hawk chicks are essentially helpless in the nest. This makes them vulnerable to predators that can climb trees and access the nests.
Several species will readily predate broad-winged hawk nestlings and fledglings:
- Raccoons – These omnivorous mammals are adept climbers and one of the most frequent nest predators of broad-winged hawks.
- Snakes – Rat snakes and some other climbing snakes will consume nestling hawks.
- Crows – American crows sometimes raid nests for eggs or young chicks.
- Blue jays – While less aggressive than crows, blue jays may opportunistically raid nests.
- Squirrels – Nocturnal species like flying squirrels can access nests and take nestlings.
- Opossums – These tenacious climbers will eat nestlings and eggs.
- Great horned owls – One of the top aerial predators of broad-winged hawks. They attack nests at night.
- Red-tailed hawks – Larger hawks may attack the nests of smaller broad-winged hawks.
The vulnerability of chicks and fledglings is one reason broad-winged hawks favor relatively inaccessible nest sites high up in dense woods. However, successful predation still occurs. One study in New York found that only 48% of broad-winged hawk nestlings survived to fledge from successful nests. Predation was the primary cause of mortality.
Juveniles
After fledging the nest, juvenile broad-winged hawks face the continued threat of predation as they hone their flying skills over several weeks. Their flight feathers and muscles need time to develop adequate strength and coordination for skilled flight. As a result, many juveniles end up caught by predators on the ground or in trees:
- Great horned owls
- Red-tailed hawks
- Northern goshawks
- Cooper’s hawks
- Bobcats
- Foxes
- Crows
A landmark study on post-fledging mortality found that 70% of juvenile broad-winged hawks died within 5 weeks after leaving the nest. Half of the mortality was attributed to predation. Survival rates increase as juveniles become more adept flyers and less vulnerable. However, the high predation rates help explain why broad-winged hawks lay up to 3 eggs per clutch – even though 1-2 offspring typically fledge per nest. Producing multiple young improves the odds that at least one juvenile will survive and mature.
Adults
Once broad-winged hawks reach adulthood, fewer predators can threaten them. Their powerful talons, sharp beaks, quick reflexes, and speed in flight make them less vulnerable.
However, some predators do occasionally kill and eat adult broad-winged hawks:
- Great horned owls – Still the top predator, especially capable of night attacks.
- Red-tailed hawks – May fight and kill broad-winged hawks over territory.
- Northern goshawks – The fierce accipiter hawks view broad-wings as prey.
- Golden eagles – At least on rare occasions, they have killed broad-winged hawks.
There is at least one documented observation of a nesting pair of bald eagles killing and eating a broad-winged hawk that ventured too close to the eagle nest.
Adult broad-winged hawks may also fall prey to predators when sick, injured, or otherwise weakened and vulnerable. Otherwise, healthy adults have relatively few predation threats from other animals.
Predation Pressure and Evolution
The considerable predation pressure on broad-winged hawks throughout their life cycles has shaped the evolution of certain traits and behaviors:
- Cryptic plumage – Their brownish barring helps camouflage broad-winged hawks against tree bark where they perch and nest.
- Life strategy – Producing multiple young improves odds at least one will survive despite heavy nest predation.
- Nest defense – They aggressively attack potential nest predators, diving at intruders.
- Mobbing – Broad-winged hawks join together to mob predators like great horned owls near their nest sites.
- Nest spacing – They nest high up and spaced widely apart to reduce predation risk.
Strong natural selection has favored broad-winged hawks that best avoid predators and defend nests. Predation is a major evolutionary driver underlying many of their physical and behavioral adaptations.
Conclusion
Broad-winged hawks face heavy predation pressure throughout their lives from a diverse array of predators. Nestlings and fledglings are especially vulnerable to being eaten by arboreal mammals, snakes, and predatory birds. Many juveniles also fall victim to predators on the ground and in the air as they learn to fly skillfully. Even adults may be attacked in rare instances by powerful owls, eagles, and other hawks. This significant threat from predators has shaped the evolution of broad-winged hawk behaviors, life history strategies, and physical traits that help them evade predators or defend against them. Their adaptions provide some assistance, but broad-winged hawks remain an important prey species for numerous predators across North America.