Red-shouldered hawks are medium-sized raptors found throughout eastern North America. They are year-round residents across much of their range. Red-shouldered hawks are territorial and often reuse the same nesting sites year after year. But do these hawks consistently return to the exact same nest each breeding season?
The Nesting Habits of Red-Shouldered Hawks
Red-shouldered hawks build nests high up in trees, often in wetland areas or along rivers. Nests are typically constructed of sticks and twigs and lined with bark, leaves, moss, and other soft materials. Red-shouldered hawk nests can grow very large over time, up to 2-3 feet wide and 1-2 feet tall. Old nests tend to be flatter with a more compact center as they accumulate more material each year.
Breeding pairs begin rebuilding and refurbishing nests in late winter and early spring for the upcoming breeding season. Both the male and female participate in nest maintenance and construction. Old nests are repaired and added to, while completely new nests may be built as well. Trees of many species are used for nesting, including oaks, pines, cypresses, maples, poplars, and beech. Usually the nest tree is one of the larger trees in the area, providing an unobstructed view of the surroundings.
Do They Use the Same Nest Every Year?
Red-shouldered hawks exhibit high nest site fidelity, meaning they return to use the same nesting territory each year. However, they do not always use the exact same physical nest. While pairs may reuse a nest in subsequent years, nest sites usually include one or more alternate nests called subsidiary nests. These are typically older nests built in previous years within the pair’s territory.
Within their territory, a red-shouldered hawk pair may maintain 2-5 different nests total. The alternate nests provide insurance against destruction of the primary nest by storms or other causes. Pairs may even rotate between nests, using a different one each year while maintaining the unused ones. However, there is usually a preferred nest that gets the most use and maintenance.
Advantages of Site Fidelity
There are several advantages to red-shouldered hawks using the same nesting sites annually:
- Reusing an existing nest takes less energy than building a brand new one.
- Old nests provide an established, stable structure.
- Returning to a familiar site may improve breeding success.
- Site fidelity helps preserve optimal habitat by continually occupying it.
- Young hawks may return to their natal area to breed.
Site fidelity is common among birds of prey and other birds that nest in cavities or build large nest structures. The time and energy invested make it beneficial to reuse nesting spots when possible. Though they may not use the exact same nest every year, red-shouldered hawks gain an advantage by maintaining fidelity to their chosen breeding territories.
What Factors Influence Nest Site Choice?
If red-shouldered hawks do not always reuse the same physical nest, what factors lead them to choose one nest over another within their territory?
Nest Condition
The overall integrity and quality of the nest structure likely plays a role. Hawks preferentially use nests that are in good condition and able to provide adequate support and protection. Extreme weather or other damaging events can render nests unusable over time. One study in New York found red-shouldered hawks chose nests with sturdier bases and more compact shapes.
Nest Tree Health
The hawks may also select nest sites based on the health and stability of the nest tree itself. They tend to favor live trees over dead ones, and will abandon nests in trees that decay significantly or are damaged. One tracking study found red-shouldered hawks consistently chose nests in live trees rather than dead snags when given a choice.
Food Availability
Access to sufficient food resources may also be a factor in nest selection. Having plentiful food nearby helps ensure the hawks can effectively feed both incubating females and demanding nestlings. One Ohio study found red-shouldered hawks preferred nesting areas closer to wetlands with higher amphibian abundance.
Disturbance
Red-shouldered hawks appear to avoid excessive human disturbance when selecting nest sites. Pairs may switch nests between years if one site experiences increases in disruptive activities like construction, logging, or recreational use. Minimal disturbance allows the sensitive hawks to nest undisturbed.
Predation
Predation risks can also prompt red-shouldered hawks to change nests. The primary predators of eggs and nestlings are raccoons, crows, jays, and rat snakes. Hawks may switch nests after a predation event to find a safer location less vulnerable to predators.
Weather and Vegetation
Weather damage and changes in vegetation around the nest are other factors that can render a nest less suitable from one year to the next. Hawks using alternate nests may simply be responding to vegetation growth or recent storms toppling branches around their preferred site.
How Long Are Red-Shouldered Hawk Nests Used?
The nests built and maintained by red-shouldered hawk pairs can potentially be used for many years. One long-term nesting study found the average nest lifespan was 5 years. However, active use ranged from 2 to 15 years at different nests. Here is an overview of how long red-shouldered hawk nests may remain in use:
Nest Lifespan | Details |
---|---|
1 year | Nests used for only a single breeding attempt are not uncommon. These may be brand new nests or repaired older nests. |
2-5 years | This seems to be the typical lifespan for most active red-shouldered hawk nests. |
5+ years | Some nests remain in use by breeders for 5-15 years or more. These are likely high quality nests in optimal, undisturbed sites. |
Abandoned | Nests may be abandoned permanently for various reasons like tree loss, disturbance, or declining site suitability. |
With proper long-term maintenance by hawk pairs, nests can potentially remain functional for well over a decade. But more often, alternating between multiple alternate nests in a territory allows each one a chance to be repaired and rebuilt.
Do Juveniles Return to Their Natal Nest?
When red-shouldered hawks reach adulthood at 1-2 years old, some may return to their general natal area to search for a mate and establish a nesting territory. This natal philopatry helps maintain stable local populations, as offspring recruit back into suitable habitat.
Young hawks do not always return precisely to their actual birth nest. In one California study, no banded nestlings returned to use their exact natal nest in subsequent years. However, many did establish breeding territories nearby within 1-5 miles of their nest of origin.
Dispersing juveniles may be unable to claim a natal nest for various reasons:
- The nest was destroyed
- Their parents still control the territory
- Other hawks now occupy the habitat
- A more suitable site is available nearby
So while juveniles do not always return to the exact same physical nest, many red-shouldered hawks exhibit natal site fidelity by settling close to their original home range. Familiarity with a successful nesting area helps young birds establish their own breeding territories.
How Does Nest Use Vary Across Their Range?
The nesting behaviors of red-shouldered hawks may vary somewhat across different portions of their widespread breeding range in North America. Here are some regional differences that have been noted:
Region | Nesting Patterns |
---|---|
Florida | May build new nests more frequently due to hurricane damage to old nests |
Great Lakes | Higher nest reuse from year to year |
Southwest | More likely to use man-made structures for nesting |
Pacific Coast | Favor nesting in giant sequoia trees when available |
Northeast | Switch nests more frequently, higher rate of new nest construction |
These variations may reflect differences in habitat, disturbance levels, climate, nest site availability, and life history strategies across the broad landscape inhabited by red-shouldered hawks.
Conclusion
Red-shouldered hawks demonstrate a high degree of nest site fidelity, returning to breed in the same general territory each year. However, they do not always reuse the exact same physical nest. Pairs usually maintain and alternate between 2-5 different nests built previously within their home range. Nest choice from year to year depends on a variety of factors like nest condition, tree health, food resources, predation risk, and disturbance levels. Reusing existing nest sites benefits the hawks by saving energy and providing established structures. With proper maintenance, individual nests may remain active for 5+ years on average. While juvenile hawks may not return to their natal nest, many do recruit back into suitable habitat nearby as adults, helping maintain stable populations. Overall nest use shows regional variations across the red-shouldered hawk’s widespread range.