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All photos & text © Bill Hilton Jr.
The first flight feather (or primary feather, at top) of the Ruby-throated
Hummingbird (Archilochus colubris) is thin, asymmetrical, and slightly
curved--characteristics that enable the wing to slice through the air for
optimal speed. The tail feathers are broad and nearly symmetrical and
assist in lift, braking, and steering. The tips of the outer tail
feathers (lower feather above) are white in females and first-year males.
MASS: About 3-4g (a nickel weighs about 5g); may nearly double mass prior to migration by putting on extra fat
LENGTH: About 8.5cm (3.5") from tip of bill to tip of tail
FLEDGLING SIZE: Hummingbirds are full-grown when they leave the nest; baby hummingbirds cannot fly
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WING BEATS: About 60-80 times per second in normal flight, up to 200 times per second in courtship dives
SPEED: Normal flight about 25mph; up to 65kph (40mph) in a courtship dive
FLIGHT MUSCLES: Make up about 25% of RTHU's weight (compared to 5% pectoral muscle weight in human beings)
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DISTANCE: About 845km (525mi) non-stop across the Gulf of Mexico, and then up to another 1,600km (1,000mi) into Central America; RTHU that nest in Canada must also fly from there to the Gulf Coast, a distance of another 1,600km (1,000mi) or so.
ELAPSED TIME: Estimated 20 hours to fly across the Gulf of Mexico. (Some RTHUs may go overland through Mexico.)
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HEARTBEATS: About 250 times per minute while at rest, about 1,220 per minute while flying
HEART SIZE: About 2.5% of total body weight
BREATHING: About 250 breaths per minute while at rest
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NEST SIZE: Inner diameter of about 4cm (1.5"); the outside of the nest is about 6cm (2.25") tall.
NEST MAKEUP: Spun by the female from spiderwebs and plant material, camouflaged with bits of lichen, lined with plant down
NEST LOCATION: Eastern United States and southern Canada in mixed woodlands, orchards, suburban areas with shade trees, etc.; often on an "edge" between open area and woods
NEST SITE: 2-18m (6-50') above ground, usually attached to a small, downward-sloping twig and often near water; nest site--but not the nest--may be used from year to year
EGG SIZE: 8mm x 13mm (.25" x .5"), roughly the size of a small jellybean
EGG COLOR: White, non-glossy
NESTLINGS: Chicks are naked and about 2.5cm (1") long at hatching. Mass is doubled each day over the first several days.
NUMBER OF EGGS PER NEST: 2, sometimes 1, almost never 3
INCUBATION: About 16-18 days (perhaps longer in cool weather), by female only
BROOD PERIOD: About 21 days (perhaps longer in cool weather), by female only
FEEDING OF YOUNG: Female collects nectar and tiny insects in her crop, then regurgitates the slurry into mouths of nestlings
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AVERAGE AGE: Most hummingbirds die within their first year; those that don't probably live an average of 3 years or so
RECORD AGE: The oldest known RTHU is listed at about 9 years
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RATE: Eats about its weight in nectar or sugar water each day.
FREQUENCY: About 5-10 times per hour for 30-60 seconds each time
BODY TEMPERATURE: 40.5 degrees C (105-108 degrees F)
TORPOR: On cold nights, a RTHU can lower its body temperature by about 20 degrees C (30 degrees F), thus conserving energy that we be used to maintain its normal temperature. The next morning, the RTHU speeds up its metabolism and get its body temperature back up to normal within a few minutes.
ENERGY USE: On a typical day, a RTHU needs about 10 calories of food to survive. This can come in the form of carbohydrates (sugar water or flower nectar) or fats and proteins (primarily from tiny insects and spiders).
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BANDING: About 170,000 RTHU have been banded in North America in the last century; none has ever been reported as recovered or recaptured on the wintering grounds in Mexico or Central America.
FEATHERS: A typical RTHU has 940 feathers.
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Go back to Ecological Relationships; return to Ruby-throated Hummingbird Main Page
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