|Archilochus colubris (Ruby-throated Hummingbird)|
|The Ruby-throated Hummingbird (Archilochus colubris), is a small hummingbird. It is the most common species of hummingbird in the eastern half of North America and the only hummingbird that breeds east of the Mississippi River.
The Ruby-Throated Hummingbird is 7-9 cm long with an 8-11 cm wingspan, and weighs 2-6 g. Adults are solid metallic green above and greyish white below, with near-black wings. The bill is moderately long, straight and very slender. The adult male has an iridescent ruby red throat patch (gorget) narrowly bordered in black at the upper margin, which may appear black in some lighting, and a dark forked tail. The female has a slightly notched tail with outer feathers banded in green, black, and white and a whitish throat that may be plain or lightly marked with dusky streaks or stipples. The male is smaller than the female, and has a slightly shorter bill. A moult of feathers occurs once per year, beginning in late summer, pausing during migration, and resuming on the wintering grounds.
The breeding habitat is throughout most of eastern North America and southern Canada, in deciduous and pine forests and forest edges, orchards, and gardens. The female builds a nest in a protected location in a shrub or tree.
The Ruby-throated Hummingbird is migratory, most individuals spending the winter in Mexico or Central America.
Ruby-throated hummingbirds are solitary. Adults of this species typically only come into contact for the purpose of mating, and both males and females of any age aggressively defend feeding locations within his or her territory. The aggressiveness becomes most pronounced in late summer to early fall as they fatten up for migration. They feed frequently while active during the day and when temperatures drop, particularly on cold nights, they may conserve energy by entering hypothermic torpor.
The birds feed on nectar from flowers and flowering trees using a long extendable tongue or catch insects on the wing. Tree sap and the juices of overripe fruits may substitute for nectar. Due to their small size, they are vulnerable to insectivorous predators such as flycatchers, mantids, large spiders, and large frogs. Females lay two white eggs averaging 12.9 by 8.5 mm.