Size, Flight, Migration & Site Fidelity,
Heart & Respiration, Nest & Eggs,
Longevity, Feeding & Metabolism

All photos & text © Bill Hilton Jr.

The first flight feather (or primary feather, at top) of the Ruby-throated
(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. Tips of the outer tail feathers
(lower feather above) are white and rounded in females and first-year
males, black and sharply pointed in adult males.

Adult female Ruby-throated Hummingbirds (RTHU) are 15-20% larger than adult males

MASS: About 3-4g (a nickel weighs about 5g); RTHU 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 straight-line flight about 40kph (25mph); up to 65kph (40mph) in a courtship dive

FLIGHT MUSCLES: Make up about 25% of RTHU weight (compared to 5% pectoral muscle weight in human beings)

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DISTANCE: At most 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 or short-cut the Gulf flight by flying from the Texas coast into 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: Diameter of the central depression is about 4cm (1.5"); the outside of the RTHU nest is about 6cm (2.25"); height is about 5cm (2")

NEST MAKEUP: Spun by the RTHU female only 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; RTHU seldom nest on human-made structures

NEST SITE: 2-18m (6-50') above ground, usually attached to a small, downward-sloping twig and often near water; a successful nest site--but not the nest itself, which seldom survives the winter--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 RTHU female ONLY

BROOD PERIOD: About 21 days (perhaps longer in cool weather), by RTHU female ONLY

FEEDING OF YOUNG: RTHU female collects nectar and tiny insects in her crop, then regurgitates the slurry into mouths of nestlings; male RTHU does not feed young

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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. RTHU banded at Hilton Pond and recaptured have reached the six-year mark

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: Feeds about 5-10 times per hour for 30-60 seconds each time; RTHU do NOT feed constantly (in fact, they go all night without eating, and during nesting season females spend much of their time incubating)

BODY TEMPERATURE: Normally at about 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 200,000 RTHU have been banded in North America in the last century; none has ever been reported as recovered or recaptured on wintering grounds in Mexico or Central America. (One RTHU, a female banded in Guanacaste Province, Costa Rica in January 2008 by Operation RubyThroat's Bill Hilton Jr., was found in Baxley, Georgia USA in June of that year. This is the ONLY hummingbird of any species banded on its wintering grounds in the Neotropics and encountered later within its breeding range in North America.)

FEATHERS: A typical RTHU has 940 feathers, all of which are replaced each year

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Go back to Ecological Relationships; return to Ruby-throated Hummingbird Main Page

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