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Swainson's Hawk
Swainson's Hawk (*Buteo swainsoni*) is a large, broad-winged raptor of the Americas, renowned for its impressive long-distance migrations between North and South America. It plays a crucial role in controlling rodent and insect populations within its breeding and wintering grounds. This species exhibits remarkable adaptability, thriving in open grasslands, prairies, and agricultural landscapes. It is named after William Swainson, a British ornithologist.
43-56 cm
Length
117-137 cm
Wingspan
Least Concern
Conservation Status
Distribution
Breeds primarily in western North America, from Alaska and Canada south to northern Mexico. Winters mainly in the pampas of South America, particularly Argentina. Migrates through Central America and Mexico.
Lifespan
Up to 20 years in the wild; longer in captivity.
Swainson's Hawk's Habitat
Habitat Types
Grasslands, Prairies, Savannas, Agricultural fields
Climate Zones
Temperate, Subtropical
Adaptations
Broad wings and soaring flight are well-suited for long-distance migration and efficient hunting over open terrain. Adaptable to human-modified landscapes like pastures.
Variations
No formally recognized subspecies, but slight variations in plumage coloration exist across its range.
Appearance
Breeding Plumage
Plumage is generally similar year-round, but can be fresher after molting.
Seasonal Feather Changes
Minor variations; molting occurs primarily on wintering grounds.
Sex Based Plumage Differences
Minimal sexual dimorphism in plumage. Exists in light, dark, and intermediate color morphs.
Notable Features
Dark bib contrasting with lighter belly (in light morph), Long, pointed wings, Relatively short tail
Diet and Feeding
Primary Foods
Small mammals (voles, mice, ground squirrels), Insects (grasshoppers, crickets), Reptiles, Amphibians, Birds (less common)
Foraging Behavior
Hunts by soaring and scanning the ground, or by perching on fence posts or utility poles. Will also walk or run on the ground to capture insects.
Specializations
Flexible diet allows it to adapt to varying prey availability during breeding and migration.
Seasonal Diet Variations
Diet shifts dramatically between breeding and non-breeding seasons. Primarily insects (especially grasshoppers) during migration and on wintering grounds; more mammals during breeding season.
Behavior
Social Structure
Generally solitary or in pairs during the breeding season. Forms large flocks during migration and on wintering grounds.
Communication
Kee-eer call (used for alarm and territorial defense), Whistling calls, Visual displays (aerial displays during courtship)
Migration
One of the longest migrations of any North American raptor. Travels in large flocks (kettles) along established routes, utilizing thermals for soaring flight. Travels thousands of kilometers between breeding and wintering areas.
Territorial or Group Behaviors
Territorial during breeding season, defending nesting areas. Highly gregarious during migration and winter, forming large roosts.
Conservation
Threats
Habitat loss (conversion of grasslands to agriculture), Pesticide use (reducing prey availability and causing direct poisoning), Collisions with vehicles and wind turbines, Climate change (altering prey distribution and migration patterns)
Protection Programs
Migratory Bird Treaty Act protection, Conservation Reserve Program (CRP) in the US (restoring grassland habitat), Monitoring of populations and migration routes
Local National Laws
Protected under the Migratory Bird Treaty Act in the US, Canada, and Mexico.
Population Trend
Stable
Population Estimates
Global population estimated at around 800,000 individuals.
Interesting Facts
They undertake one of the longest migrations of any North American raptor.
Traveling up to 12,000 miles round trip between North America and South America.
They are highly specialized for eating insects during migration.
Large flocks can consume vast quantities of grasshoppers and other agricultural pests.
Historically, large numbers were killed by pesticide poisoning in Argentina.
Efforts to reduce pesticide use have helped the population recover.
Faqs about Swainson's Hawk
What is the biggest threat to Swainson's Hawks?
Historically, pesticide poisoning was a major threat. Currently, habitat loss and degradation are significant concerns.
How can I identify a Swainson's Hawk?
Look for a large hawk with long, pointed wings, soaring in open country. Light morph birds have a dark bib contrasting with a light belly.
Do Swainson's Hawks mate for life?
They are generally monogamous during a breeding season, and some pairs may remain together for multiple years, but long-term pair bonds are not well-documented.
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