About Archilochus colubris (Linnaeus, 1758)
This species, the ruby-throated hummingbird (Archilochus colubris), measures 7 to 9 cm (2.8 to 3.5 in) in length, with an 8 to 11 cm (3.1 to 4.3 in) wingspan. Its weight ranges from 2 to 6 g (0.071 to 0.212 oz); males average 3.4 g (0.12 oz), while females are slightly larger, averaging 3.8 g (0.13 oz). Adult individuals have metallic green upper plumage, grayish white underparts, and near-black wings. Their long, straight, slender bill reaches up to 2 cm (0.79 in) in length. Ruby-throated hummingbirds have short legs, with feet that have three toes pointing forward and one backward hallux; each toe forms a claw with ridged inner surfaces that help grip flower stems or petals. The middle toe measures around 0.6 cm (0.24 in). This hummingbird can only shuffle when moving along a branch, but can use its feet to scratch and preen. The species shows clear sexual dimorphism. Adult males have an iridescent ruby red throat patch (gorget) with a narrow velvety black border along its upper margin, and a forked black tail with a faint violet sheen. The red iridescence is highly directional, appearing dull black from most viewing angles. Females have a notched tail, with outer feathers banded in green, black, and white, and a white throat that may be plain or lightly marked with dusky streaks or stipples. Males are smaller than females and have slightly shorter bills. Juvenile males resemble adult females, but usually have heavier throat markings. Ruby-throated hummingbirds molt their plumage once a year on their wintering grounds, starting in early fall and finishing by late winter. This hummingbird's breeding range covers most of the Eastern United States, as well as south-central and southeastern Canada, where it occupies deciduous and pine forests, forest edges, orchards, and gardens. Among all hummingbird species found in the United States, this species has the largest breeding range. Females build their nests in sheltered locations on shrubs or trees. The ruby-throated hummingbird is a migratory species; it spends most of the winter in Florida, southern Mexico, Central America (as far south as extreme western Panama), and the West Indies. It breeds across the eastern United States east of the 100th meridian, and in southern Canada (particularly Ontario), in eastern and mixed deciduous and broadleaved forest. During winter, it is seen mostly in Mexico and Florida. During autumn southward migration along the northern Gulf of Mexico coast, older male and female birds are better prepared for long-distance flight than first-year birds, with higher body weights and larger fuel loads. Some individuals make a nonstop 900-mile journey across the Gulf of Mexico and Caribbean from Panama or Mexico to the eastern United States during migration. Ruby-throated hummingbirds are solitary; adults are not social outside of courtship, which only lasts a few minutes. Only the female cares for her offspring. Both males and females of any age are aggressive toward other hummingbirds, and will defend territories (such as feeding territories) by attacking and chasing other hummingbirds that enter their territory. As part of their spring migration, part of the population flies across the Gulf of Mexico from Mexico's Yucatan Peninsula, arriving first in Florida and Louisiana. This feat is impressive because an 800 km (500 mi) non-stop flight over water would seemingly require more caloric energy than the 3 g (0.11 oz) adult hummingbird's body can store. However, researchers have found that these tiny birds can double their fat mass to prepare for the Gulf crossing, and expend all of this fat calorie reserve during the 20-hour non-stop crossing, when no food or water is available. Hummingbirds have one of the highest metabolic rates of any animal: heart rates can reach 1260 beats per minute, breathing rate is around 250 breaths per minute even at rest, and resting oxygen consumption is about 4 ml oxygen per gram of body mass per hour. During flight, oxygen consumption per gram of muscle tissue in hummingbirds is roughly 10 times higher than that measured for elite human athletes. Ruby-throated hummingbirds feed frequently while active during the day. When temperatures drop, especially on cold nights, they may enter hypothermic torpor to conserve energy. The main components of this hummingbird's diet are nectar from flowers and flowering trees, plus small insects and spiders. While hummingbirds are widely known for feeding on nectar, small arthropods are an important source of protein, minerals, and vitamins for adult ruby-throated hummingbirds. The species shows a slight preference for red, orange, and bright pink tubular flowers as nectar sources, but it will also visit flowers not adapted to hummingbird pollination, such as willow catkins. Occasionally, its diet may also include sugar-rich tree sap taken from sapsucker wells. The birds feed from flowers using a long, extendable tongue, and catch insects mid-flight or glean them from flowers, leaves, bark, and spider webs. Young hummingbirds are fed insects to get protein, because nectar does not provide enough protein for growing birds.
