This bird is an amazingly acrobatic flyer. It can hover in one spot, and fly forward and backward. It does not need to push off with its feet to take flight, and can stop almost instantly when returning to a perch. It also shows remarkable endurance during migration, particularly for such a small creature. Unlike many other species of bird, the Ruby-throated female has little to do with the male after mating. She builds her nest and raises her young on her own.

Physical Description:

Length: 76 to 95 mm (less than 4 inches)

Physical characteristics: This is a tiny bird with a long, thin bill. Both sexes have metallic green upperparts, and white underparts with darker shading on the flanks. The male has a black face and chin, and the telltale iridescent red throat. The female has a white chin and throat that are spotted with black. She also has white tips on her outer tail feathers.

Voice: Song is a faint rattling series of t,t,t,t,t.

Breeding habitat:
During the breeding season, this hummingbird occurs in mixed deciduous forests, open woodlands, clearings and forest edges, orchards, gardens and parks.

Mating system:
There is no pair bond in this species. Males and females associate only during mating. Ruby-throated Hummingbirds are considered polygynous, with the male mating with a number of females who enter his territory.

Nest:
The nest is built solely by the female. Located on a limb of a deciduous tree or shrub, the nest is a cup made of plant down, and held together by spider webbing. Lichens are attached to the outside, giving the nest the appearance of a natural knob of the branch. Often the nest is placed over water and under a canopy of leaves.

Eggs:
The eggs are white with no markings. Occasionally the clutch will contain one egg, but the usual number is two. 13mm (0.5 in.).

Chick development:
Hatching occurs after 11 to 14 days of incubation by the female. Chicks are born altricial and are about the size of honeybees. They fledge at anywhere from 2 - 3 weeks of age.

Diet:
The diet includes nectar, lapped from flowers (a preference is shown for red flowers) while hovering in flight, and small insects, caught on the wing. Tree sap is taken if the supply of nectar is low. Chicks are fed the same diet, initially by regurgitation by the female.

Parasites:
A hummingbird caught at Oconaluftee, North Carolina, in July of 2005 had feather mites of the genus Allodectes (Proctophyllodidae), representing an undescribed species and the first time this genus, widely distributed in South America, has been recorded in the United States (Reeves et al. 2007). These mites have not been found on any of dozens of hummingbirds examined since in other locations.
The louse Trochiliphagus lineatus (Osborn) was collected on a hummingbird in Cataloochee Valley, North Carolina, in August of 2001 (Reeves et al. 2007).

Conservation Biology:
This species does not appear to be threatened. There is some concern that feeders may delay migration, but most evidence does not support this. However they may indirectly contribute to some hummingbird deaths from cat predation and collision with windows.

Breeding: The Ruby-throated Hummingbird is found in southeastern Canada and throughout the entire eastern half of the United States. This is the only species of hummingbird found in the eastern United States during the breeding season.

Winter: This species is a neotropical migrant that winters in southwestern Mexico, and south and east to Central America. Many birds fly over the Gulf of Mexico in a nocturnal, non-stop flight during migration; others follow the coastline of Texas.

The Ruby-throated Hummingbird is a common breeding bird species in the Park. This species is most common at the lower elevations in the Park and is often associated with open areas. When the bee balms (Monarda sp.) bloom at high elevations (above 4,000 feet) in July, large numbers of these birds will frequent patches of this nectar source, but it is unclear whether they are moving up from lower elevation or coming from outside the Park. However, hummingbirds may be observed in a variety of habitats in the Smokies.

A survey of breeding birds in the Park, performed from 1996 to 1999, ranked Ruby-throated Hummingbird as the 54th most abundant species out of 113 species observed during the breeding season. Estimates from this survey indicate that overall Ruby-throated Hummingbird density in the Park during the breeding season is approximately 0.55 pairs per hectare.

References:

Alsop, F. J. III. 1991. Birds Of The Smokies. Great Smoky Mountains History Association, Gatlinburg, Tennessee.

Bent, A. C. and Collaborators. 1996 - 2002. Ruby-throated Hummingbird, In Life Histories of Familiar North American Birds, ed., Patricia Query Newforth.

Committee on Classification and Nomenclature of the American Ornithologists' Union. 2002. Forty-third supplement to the American Ornithologists' Union Check-list of North American Birds. The Auk 119: 897-906.

Ehrlich, P. R., D. S. Dobkin, and D. Wheye. 1988. The Birder's Handbook: a Field Guide to the Natural History of North American Birds. Simon and Schuster, Inc., New York.

Elphick, C., J. B. Dunning, Jr., and D. A. Sibley, eds. 2001. The Sibley Guide to Bird Life and Behavior. Alfred A. Knopf, New York.

Gough, G. A., Sauer, J. R., Iliff, M. Patuxent Bird Identification Infocenter. 1998. Version 97.1. Patuxent Wildlife Research Center, Laurel, MD. http://www.mbr-pwrc.usgs.gov/id/framlst/infocenter.html.

Robinson, T. R., R. R. Sargent and M. B. Sargent. 1996. Ruby-throated Hummingbird ( Archilochus colubris ). In The Birds of North America, No. 204 (A. Poole and F. Gill, Eds.). Philadelphia: The Academy of Natural Sciences; Washington, DC: The Americ

Reeves, W. K., L. A. Durden, C. M. Ritzi, K. R. Beckham, P. E. Super, and B. M. O?Connor. 2007. Ectoparasites and other ectosymbiotic arthropods of vertebrates in the Great Smoky Mountains National Park, USA. Zootaxa.

Sibley, D. A. 2000. The Sibley Guide to Birds. Alfred A. Knopf, New York.

Stupka, A. 1963. Notes on the Birds of the Great Smoky Mountains National Park. University of Tennessee Press.