The Red-Shouldered Hawk (Buteo lineatus) is a medium-sized raptor recognized by its reddish-brown barring on the chest and a rusty patch on the shoulder. This bird of prey primarily inhabits mature deciduous and mixed-wood forests, often near wetlands across eastern North America and parts of California. Understanding the species’ lifespan is important for conservation efforts, allowing biologists to track population health and identify vulnerable life stages.
Documented Lifespan: Wild vs. Captivity
The lifespan of a Red-Shouldered Hawk varies significantly between wild and captive populations. In the wild, established adult hawks that survive their first year typically live for about five to ten years. Banding studies suggest the mean lifespan is much lower, around 25.6 months, due to high first-year mortality rates. The maximum recorded age in the natural habitat is nearly 20 years, with one banded individual documented at 19 years and 11 months.
Hawks living in human care benefit from consistent food sources, veterinary treatment, and the complete absence of natural predators or environmental hazards. This protected environment allows them to significantly outlive their wild counterparts. Maximum ages in captivity often exceed 25 years, demonstrating the species’ biological potential when freed from the pressures of the wild.
The Critical First Year: Juvenile Mortality Rates
The journey from hatchling to breeding adult presents the greatest challenge, with the vast majority of mortality occurring within the first year of life. Approximately 50 to 60 percent of young hawks do not survive to their first birthday, a period when they are particularly susceptible to natural attrition. Newly fledged birds often struggle with the steep learning curve of hunting, which can lead to death by starvation before they master the complex skills needed to secure prey.
Young hawks are also highly vulnerable to natural predators before they reach full size and competence. The Great Horned Owl (Bubo virginianus) is a significant threat, preying on eggs, nestlings, and even incubating female adults. Juvenile dispersal, the period when young birds leave their natal territory to find a home range, also exposes them to novel risks as they venture into unfamiliar habitats and compete for resources.
Environmental Factors Affecting Adult Longevity
Once a Red-Shouldered Hawk survives its first year and establishes a territory, its longevity is often determined by a range of human-influenced environmental factors. Habitat fragmentation and loss, caused by deforestation and development, directly reduce the availability of suitable nesting and foraging sites, increasing stress and competition among mated pairs. Collisions with vehicles and man-made structures, such as windows and power lines, are frequent causes of premature death in established adults.
Secondary poisoning presents another major threat, particularly from the widespread use of anticoagulant rodenticides (ARs) in residential and agricultural areas. When a hawk ingests a poisoned rodent, it suffers secondary toxicosis. The AR compounds interfere with the bird’s ability to clot blood, leading to fatal internal hemorrhaging. Adult longevity is also modestly affected by diseases and parasites, including blood parasites and the protozoan Trichomonas gallinae, which can weaken the birds over time.