Ruby-throated hummingbirds are found in North and Central America. They breed throughout the eastern United States, east of the 100th meridian, and in southern Canada where there is eastern and mixed deciduous forest. The species winters in southern Mexico, Central America (as far south as Costa Rica), and in the West Indies. (Robinson, et al., 1996)
During the breeding season, this species can be found in deciduous and pine forests and forest edges, orchards, and gardens. During the winter, ruby-throated hummingbirds live in tropical deciduous forests, citrus groves, forest edges, hedgerows, along rivers and marshes, and in old fields. (Robinson, et al., 1996)
Ruby-throated hummingbirds are tiny birds. They are 7.5 to 9.0 cm long and weigh approximately 3.4 g (males) to 3.8 g (females). The back and head are iridescent green, the underparts are white. Males have a brilliant red metallic throat and a forked tail. Females have a dull grayish throat, and a square, white-tipped tail. Immature ruby-throated hummingbirds look similar to adult females, though young males may have a few red feathers on their throat. (Robinson, et al., 1996)
Ruby-throated hummingbirds are presumed to be polygynous. However, polyandry (females have multiple mates) and polygynandry (both males and females have multiple mates) may also occur in this species. These birds do not establish breeding pairs; they separate after copulation and females provide all parental care.
Males return to the breeding area in the spring and establish a territory before the females arrive. When the females return, males court females that enter their territory by performing courtship displays. They may begin by erecting their red throat feathers and harassing the female. They perform a “dive display” by flying in looping dives above the females head. If the female perches, the male switches flying in very rapid horizontal arcs less than 0.5 m in front of the female. During these displays, the male's wings can beat up to 200 times per second (as opposed to the normal 90 beats per second). If the female is receptive to the male, she may give a “mew” call and assume a solicitous posture with her tail feather cocked and her wings drooped. After copulation, the male and female separate. (Robinson, et al., 1996)
The female selects a nest site and builds the nest. Nests are usually built near the tip of a downsloping branch, below a leaf canopy and above a fairly open area. They are constructed of plant material, particularly thistle and dandelion, but spider webs, bud scales and pine resin may also be used. The outside of the nest is decorated with lichens. When the nest is complete, the female lays 1 to 3 (usually 2) eggs. The eggs are incubated by the female for 10 to 14 days. The chicks are altricial at hatching, and leave the nest 18 to 22 days after hatching. The female continues to feed the chicks for 4 to 7 days after they hatch, until they are 22 to 25 days old. These birds can probably breed the next season at age 1 year. Ruby-throated hummingbirds can raise up to three broods each year. (Robinson, et al., 1996)
After copulation, all parental activities are the responsibility of the female. The female builds the nest, lays and incubates the eggs, broods the chicks and feeds them until they are 22 to 25 days old. The male does not provide any parental care. (Robinson, et al., 1996)
One study at Powdermill Nature Reserve in Pennsylvania found mean annual survivorship to be 31% for males and 42% for females. The oldest known wild ruby-throated hummingbirds lived at least 9 years (female) and 5 years (male). Reasons for higher mortality in males may include loss of weight during the breeding season due to the high energetic demands of defending a territory followed by energetically costly migration. (Robinson, et al., 1996)
Ruby-throated hummingbirds are solitary. Adults of this species typically only come into contact for the purpose of mating. Males of this species are territorial, and communicate with each other primarily through vocalizations. If a neighboring male intrudes on a male’ territory, the resident male emits a single note, which is repeated at increasing volume. If the intruder does not leave the territory, the resident male will chase him, and if needed, jab him with his bill or strike with his feet.
Ruby-throated hummingbirds are diurnal. They are active during the day. In cold conditions, particularly on cold nights, ruby-throated hummingbirds save energy by entering hypothermic torpor. Hypothermic torpor is a state similar to hibernation in which the body is allowed to cool down several degrees, and body functions slow down to conserve energy.
Ruby-throated hummingbirds migrate between breeding and wintering grounds. Many ruby-throated hummingbirds migrate as far as 1,600 km roundtrip each year, flying non-stop across the Gulf of Mexico. In order to complete this grueling journey, these hummingbirds often double their body mass before beginning migration. The return flight to breeding grounds is timed so that arrival coincides with flowering of food plants in a given region. (Robinson, et al., 1996; Robinson, et al., 1996)
There is no information available about the home range of this species at this time. (Robinson, et al., 1996)
Ruby-throated hummingbirds use tactile and visual cues, vocalizations and perhaps olfactory cues to communicate and perceive their environment. In addition to the visible light spectrum, ruby-throated hummingbirds can see in the blue-violet range and near UV (370 to 570 nm). This ability may help them find and identify flowers that are potential food sources. Ruby-throated hummingbirds may also be able to find and discriminate between food sources using olfactory cues.
The vocalizations of ruby-throated hummingbirds are rapid, squeaky chips, and are used primarily for agonistic threats. For example, males may vocalize to warn another male that has entered their territory. If vocalizations are not effective, males will chase other males out of their territory, striking them with their feet or bill when necessary. (Robinson, et al., 1996)
The primary food sources of ruby-throated hummingbirds are floral nectar and small insects. When nectar is scarce, they will also consume tree sap. Ruby-throated hummingbirds eat nectar from a variety of different flowering plants, including red buckeye (Aesculus pavia), jewelweed, columbine (Aquilegia canadensis), trumpet creeper (Campsis radicans), red morning-glory (Ipomea coccinea), trumpet- or coral-honeysuckle (Lonicera sempervirens), fly-honeysuckle (Lonicera canadensis), cardinal flower (Lobelia cardinalis), catchflies (Silene) and fire-pink (Silene virginica). Insects eaten by this species include mosquitoes, spiders, gnats, fruit flies (genus Drosophila) and small bees.
Ruby-throated hummingbirds are particularly attracted plants that produce red flowers. They consume twice their body weight in food each day. While eating, these birds hover above the plant, using their long beaks to suck out the flower's' nectar. (Robinson, et al., 1996)
Adult ruby-throated hummingbirds are vulnerable to predation by raptors, including loggerhead shrikes and sharp-shinned hawks. Blue jays predate nestlings. However, the most common predator of ruby-throated hummingbirds is probably house cats. (Robinson, et al., 1996)
This species plays an important ecosystem role as pollinators. In fact, some species such as trumpet creeper, a woodland vine, seem to be adapted specifically to pollination by ruby-throated hummingbirds.
Ruby-throated hummingbirds compete with other hummingbird species for food. Where their ranges overlap, ruby-throated hummingbirds appear to be generally subordinate to other hummingbird species. (Robinson, et al., 1996)
Ruby-throated hummingbirds pollinate many native and cultivated plant species.
There are no known adverse affects of ruby-throated hummingbirds on humans.
Due to their small size and brilliant plumage, ruby-throated hummingbirds were hunted for collection during the nineteenth century. Although the species was a great prize, the population never became threatened and the species remains common in its range. There are an estimated 7,300,000 ruby-throated hummingbirds worldwide.
This species is protected under the Migratory Bird Treaty between the U.S. and Canada, and like all hummingbirds, is listed in Appendix II of the Convention on International Trade in Endangered Species. (Robinson, et al., 1996)
Hummingbirds are known for their ability to fly backwards, upside down, and to hover. Few other birds compare in their ability to perform such aerial tricks. They also possess the fewest number of feathers ever counted on a bird.
The characteristic humming sound of each hummingbird species is determined by the speed of its wing beats; ruby throats have an extremely rapid wing beat, 53 beats per second. Like other hummingbirds, ruby-throated hummingbirds have high metabolic rates to support hovering flight, which requires 204 calories per gram per hour. Resting metabolic rate is estimated at 20.6 calories per gram per hour. (Robinson, et al., 1996)
Kari Kirschbaum (author, editor), Animal Diversity Web.
Marie S. Harris (author), University of Michigan-Ann Arbor, Robert Naumann (author), University of Michigan-Ann Arbor.
living in the Nearctic biogeographic province, the northern part of the New World. This includes Greenland, the Canadian Arctic islands, and all of the North American as far south as the highlands of central Mexico.
living in the southern part of the New World. In other words, Central and South America.
uses sound to communicate
living in landscapes dominated by human agriculture.
young are born in a relatively underdeveloped state; they are unable to feed or care for themselves or locomote independently for a period of time after birth/hatching. In birds, naked and helpless after hatching.
Referring to an animal that lives in trees; tree-climbing.
having body symmetry such that the animal can be divided in one plane into two mirror-image halves. Animals with bilateral symmetry have dorsal and ventral sides, as well as anterior and posterior ends. Synapomorphy of the Bilateria.
uses smells or other chemicals to communicate
animals that use metabolically generated heat to regulate body temperature independently of ambient temperature. Endothermy is a synapomorphy of the Mammalia, although it may have arisen in a (now extinct) synapsid ancestor; the fossil record does not distinguish these possibilities. Convergent in birds.
forest biomes are dominated by trees, otherwise forest biomes can vary widely in amount of precipitation and seasonality.
An animal that eats mainly plants or parts of plants.
offspring are produced in more than one group (litters, clutches, etc.) and across multiple seasons (or other periods hospitable to reproduction). Iteroparous animals must, by definition, survive over multiple seasons (or periodic condition changes).
marshes are wetland areas often dominated by grasses and reeds.
makes seasonal movements between breeding and wintering grounds
having the capacity to move from one place to another.
the area in which the animal is naturally found, the region in which it is endemic.
an animal that mainly eats nectar from flowers
reproduction in which eggs are released by the female; development of offspring occurs outside the mother's body.
having more than one female as a mate at one time
rainforests, both temperate and tropical, are dominated by trees often forming a closed canopy with little light reaching the ground. Epiphytes and climbing plants are also abundant. Precipitation is typically not limiting, but may be somewhat seasonal.
Referring to something living or located adjacent to a waterbody (usually, but not always, a river or stream).
scrub forests develop in areas that experience dry seasons.
breeding is confined to a particular season
reproduction that includes combining the genetic contribution of two individuals, a male and a female
one of the sexes (usually males) has special physical structures used in courting the other sex or fighting the same sex. For example: antlers, elongated tails, special spurs.
living in residential areas on the outskirts of large cities or towns.
uses touch to communicate
that region of the Earth between 23.5 degrees North and 60 degrees North (between the Tropic of Cancer and the Arctic Circle) and between 23.5 degrees South and 60 degrees South (between the Tropic of Capricorn and the Antarctic Circle).
Living on the ground.
defends an area within the home range, occupied by a single animals or group of animals of the same species and held through overt defense, display, or advertisement
the region of the earth that surrounds the equator, from 23.5 degrees north to 23.5 degrees south.
uses sight to communicate
Bull, John. Birds of New York State. Cornell University Press, 1974.
Johnsgard, Paul, A. The Hummingbirds of North America. Smithsonian Institution Press, 1983.
Mackenzie, John, P.S. Birds of Eastern North America. McGraw Hill Ryerson Limited, 1976.
Tyrell, Esther, Quesada. Hummingbirds: Their Life and Behavior. Crown Publishers Inc., 1985.
Robinson, T., R. Sargent, M. Sargent. 1996. Ruby-throated hummingbirds (Archilochus colubris). Pp. 1-16 in A Poole, F Gill, eds. The Birds of North America, Vol. 204. Philadelphia, PA: The Academy of Natural Sciences and Washington DC: The American Ornithologists Union.