The Vaux’s swift (Chaetura vauxi) is a small bird found in western North America. With its scythe-like wings and stiff, shallow wingbeats, the Vaux’s swift is built for speed. But just how fast can this bird fly?
What is the Vaux’s Swift?
The Vaux’s swift is a medium-sized swift species found along the west coast of North America. It breeds in mixed conifer and hardwood forests across western Canada, the western United States, and northern Mexico. During winter, it migrates to Mexico and Central America.
Like all swifts, the Vaux’s swift has very long, curved wings and a short, forked tail. It is glossy black overall with a faint greenish sheen on the head and back. The throat may appear grayish. It has a very short bill and tiny feet that are used primarily for clinging to vertical surfaces. The feet are too small to allow the bird to perch horizontally.
The Vaux’s swift has a wingspan of 12.6–13.8 in (32–35 cm) and weighs 1.0–1.3 oz (28–37 g). Males and females look alike. Juveniles appear sooty brown overall until their adult plumage grows in.
This agile flier catches insects on the wing. It forages high in the air over forests, plains, and towns. The Vaux’s swift roosts and nests communally in hollow trees, chimneys, and sea caves. It breeds from May to August, building a shallow nest of twigs glued together with saliva and laying 3–5 eggs.
How Do Swifts Fly So Fast?
Swifts in general are among the fastest flying birds in the world. Maximum flight speeds are estimated between 69-99 mph (111-159 km/hr) for certain large swift species. The Vaux’s swift is a bit smaller but is still an elite avian speedster.
Swifts owe their speed to several key adaptations:
- Long, curved wings providing a large wing area relative to the body size. This maximizes lift production.
- Rigid wings built for speed at the expense of maneuverability.
- Streamlined body shape to minimize drag.
- Small bill to further reduce drag.
- Very short legs and feet drawn into the body in flight.
- Lightweight skeleton and small body musculature.
- High metabolism that provides energy for continuous, fast flight.
In addition, swifts have evolved a slightly different wing shape compared to other birds that improves their flight efficiency. The wings are higher in aspect ratio, meaning they are relatively longer from tip to tip than from front to back. This shape reduces drag and allows swifts to fly faster on less power.
Measured Speeds
Direct field measurements of flight speeds in wild Vaux’s swifts have been limited. However, some studies have obtained speed estimates using radar tracking:
- Average flight speed of 35 mph (56 km/hr) during routine, diurnal flight.
- Maximum flight speed of 69 mph (111 km/hr) during panic flights when startled at the roost.
Other studies have used wing morphology measurements to estimate probable flight speeds. Based on its wing shape and size, one study predicted the maximum speed of Vaux’s swift to be between 111-130 mph (178-209 km/hr).
More direct speed measurements have been collected in wind tunnels using trained captive swifts. One 1970 study found the maximum flight speed of captive Vaux’s swifts in wind tunnel trials to be 111 mph (178 km/hr).
How Do Vaux’s Swift Speeds Compare to Other Birds?
The Vaux’s swift is widely considered one of the fastest flying land birds alongside other swifts and swallows. Here is how its speed compares to some other birds:
Bird | Maximum Speed |
---|---|
Vaux’s swift | 111 mph (178 km/h) |
White-throated needletail (swift) | 105 mph (169 km/h) |
Frigatebird | 95 mph (153 km/h) |
Peregrine falcon | 200 mph (322 km/h) |
Golden eagle | 150 mph (241 km/h) |
The Vaux’s swift is faster than many birds, but raptors like the peregrine falcon can reach considerably higher speeds when diving. The Vaux’s swift cannot match the peregrine, but its maximum horizontal flight speed ranks among the highest of all birds.
How Does Speed Help the Vaux’s Swift Survive?
The Vaux’s swift’s speed serves several key functions:
- Foraging – Swifts catch insects on the wing. High speed allows them to range widely and maximize food intake.
- Predator evasion – Speed helps swifts avoid larger predatory birds.
- Migration – The swift’s high traveling speed aids in completing long migrations quickly and safely.
- Display – Courtship displays involve high-speed dives and climbs to impress potential mates.
Remaining Mysteries About Swift Flight
While we have gained much knowledge about swifts and their flight capabilities, some questions remain unresolved:
- What speeds do swifts reach in direct, steep dives? Radar studies have yet to accurately measure this.
- How do swifts fly for such long durations at speeds over 100 mph without exhausting themselves or overheating?
- What subtle wing shape adaptations allow such efficient high-speed cruising?
- How have swifts evolved their unique musculature and metabolism to power their endurance flight?
Advanced technology like GPS tags and wind tunnel tests will continue to reveal the aerodynamic secrets of these aviation masters. After millions of years perfecting their flight abilities, there is still much we can learn from the speeds, grace, and agility of the Vaux’s swift and its relatives.
Conclusion
With its curved, rigid wings and streamlined body, the Vaux’s swift is one of the fastest flying birds in the world. Direct speed measurements and wind tunnel tests show that Vaux’s swifts can achieve horizontal flight speeds over 110 mph. This ranks among the highest speeds achieved by any bird, enabling these swifts to feed, migrate, and evade predators with great efficiency. Further study of swift flight mechanics will provide insights into the evolution of powered flight in birds.