The Ruby-throated Hummingbird is by far the most common species that
breeds in the eastern half of North America, although most states have
sporadic Rufous sightings, and Bob and Martha Sargent have banded eight
other hummingbird species as winter visitors to five southeastern states.
Ruby-throats are intensely inquisitive and thus easily attracted to feeders,
where males in particular typically display aggressive territoriality
toward rival hummers, other birds, and even insects such as bees, butterflies,
and sphinx moths. They quickly become accustomed to human presence, and
will swoop down to investigate red articles of clothing, possibly as potential
food sources. Feeders hung at windows attract as many visitors as ones
farther from structures, and the bird that claims a feeder as its territory
may spend much of the day perched nearby, guarding the food source against
intruders. Many hummingbird watchers find "Hummer Warz" endlessly
entertaining, although the chases are obviously serious business to the
hungry birds. For a short period immediately after fledging, a female
will tolerate the presence of her own young at the feeder, but they are
soon treated the same as other adult birds - as rivals in pursuit of the
food necessary to prepare for the fall migration.
Courtship is apparently very brief, if it exists at all, and once mated
the female raises the young alone. The walnut-sized nest, built by the
female, is constructed on a foundation of bud scales attached to a tree
limb with spider silk; lichens camouflage the outside, and the inside
is lined with dandelion, cattail, or thistle down. The nest will stretch
to contain the growing nestlings, and may sometimes be reused (rebuilt)
the following year.
Two white, pea-sized eggs are laid two or three days apart, which the
female will incubate from 60 to 80 percent of the day for 12-16 days.
Reports of the duration of the nestling phase vary from 14 to 31 days,
the wide range possibly varying with the availability of food; 18-23 days
is normal. when they leave the nest, the chicks are considerably larger
than their mothers: they may weigh 4.5 grams, while poor Mom is down to
only 2.5 g after the stress of raising them. Since the mother starts incubating
the first egg as soon as it's laid, that chick will hatch and fledge earlier
than its sibling; it will remain close to the nest until the other chick
is ready to fly. After leaving the nest, fledglings are fed by their mother
for about 10 days. It is thought that Ruby-throats live as long as 12
years, but the average is probably 3-5 years.
Average length: 3.5 inches (8.9 cm)
Average weight: 1/8 ounce (3.1 g)
Body temperature: 105°-108°F (40.5°-42.2°C)
Wing beats: 40-80 per second, average about 52
Respiration: 250 per minute
Heart rate: 250 beats/min resting; 1200 beats/min feeding
Flight speed: 30 mph (48 kph) normal; 50 mph (80 kph) escape; 63 mph (101
Adult male: Emerald green back, iridescent ruby red gorget (throat) that
may appear black under some lighting conditions, gray flanks, forked tail
with no white. Smaller than the female.
Adult female: Emerald green back, white breast and throat, rounded tail
with white tips. Larger than the male, with longer bill.
Juveniles: Young of both sexes look like the adult female. In August and
September, young males may develop some red spots in the gorget.
Molts: One complete molt per year, which may start during the fall migration
and continue into March. Young males acquire full ruby gorgets during
their first molt.
Gender identification is simple if the light is right: the brilliant
red gorget of the male is unmistakable. More commonly, though, the shape
and presence of white on the tail is a more reliable field mark.
Distribution and Migration
Ruby-throats breed throughout eastern to midwestern North America, from
southern Canada to the Gulf of Mexico. Most winter in Mexico, Central
America, and on Caribbean islands, although a few remain in the Gulf states
and the Outer Banks of North Carolina. Most researchers accept a remarkable
non-stop crossing of the Gulf, taking 18-20 hours. They arrive at the
coast in late February or early March, and follow the development of spring
flowers northward, reaching my home in St. Louis on April 20 +/- 2 days.
Males migrate earlier than females, in both directions; some adult males
start south as early as JUly. Our female breeding birds leave here (St.
Louis) in September, with the young of the year following; the last juveniles
depart abruptly at first frost (mid-October). By mid-November the fall
migration is essentially completed throughout North America.
A fanciful and amusing myth has arisen
regarding hummers hitching rides on other birds.
Sources: Bob and Martha Sargent, Stokes Guide to Bird Beavior,
Audubon Society Field Guide to North American Birds (Eastern Region)
For maps showing population distribution and trends, see the USGS species
account. See also the Ohio
Department of Natural Resources Profile.