Among the dazzling array of hummingbirds that grace North America, the Ruby-throated Hummingbird and the Rufous Hummingbird stand out as two of the most familiar and frequently observed species. Both species captivate birdwatchers with their vibrant colors and remarkable agility, yet they possess distinct traits that reveal their unique adaptations and evolutionary histories. Despite overlapping ranges in many parts of the United States, these hummingbirds can be challenging to distinguish, especially to novice birders, due to their similar size and shape. This article explores the taxonomy, distribution, physical characteristics, behaviors, breeding habits, and conservation status of these charismatic birds, providing a comprehensive guide to identifying and understanding these two spectacular species.
Scientific Classification
The Ruby-throated Hummingbird (Archilochus colubris) and the Rufous Hummingbird (Selasphorus rufus) both belong to the family Trochilidae, which encompasses all hummingbird species. However, they are classified into different genera that reflect their distinct evolutionary lineages and traits. The Ruby-throated Hummingbird is part of the genus Archilochus, which includes species known for their relatively slender bodies and bright iridescent throat patches. The Rufous Hummingbird belongs to the genus Selasphorus, a group characterized by their stockier bodies and often rufous or orange plumage.
The Ruby-throated Hummingbird’s scientific name, Archilochus colubris, was first described in 1758 by Carl Linnaeus. The genus name honors the ancient Greek poet Archilochus, while “colubris” is Latin for “snake,” possibly alluding to the bird’s slender, serpentine flight patterns. The Rufous Hummingbird’s name, Selasphorus rufus, reflects its striking reddish coloration; “rufus” means reddish or rusty in Latin, perfectly describing the male’s vivid orange-red plumage.
Geographic Range & Distribution
The geographic ranges of the Ruby-throated and Rufous Hummingbirds overlap in parts of the United States but are largely distinct, shaped by their migratory routes and habitat preferences. The Ruby-throated Hummingbird is the only hummingbird species that breeds commonly east of the Mississippi River. It is widespread across the eastern United States, southern Canada, and parts of the Gulf Coast, with breeding grounds extending from Texas and Florida northward through the Great Lakes region and into southern Canada. In winter, this species migrates to Central America, particularly Mexico and Panama, with some individuals wintering as far south as Costa Rica.
In contrast, the Rufous Hummingbird has a primarily western distribution. It breeds along the Pacific Coast from southern Alaska through British Columbia, Washington, Oregon, and California, extending eastward into the Rocky Mountains. Rufous Hummingbirds are notable for their long migratory journey, traveling from their breeding grounds in the northwestern United States and Canada to wintering sites as far south as Mexico’s Pacific coast and southwestern United States. Interestingly, Rufous Hummingbirds have been recorded as vagrants far outside their usual range, including sightings in the eastern United States, where they occasionally overlap with Ruby-throated Hummingbirds.
This overlap can cause identification challenges, especially during migration seasons in late summer and early fall when both species may be present in the same areas. Their differing migratory paths and timing generally reduce direct competition, allowing these species to thrive in their respective niches.
Physical Description
While both hummingbirds share similar size and body structure, key differences in plumage and morphology help distinguish the Ruby-throated and Rufous Hummingbirds. The Ruby-throated Hummingbird is slightly smaller, measuring approximately 7 to 9 cm (2.8 to 3.5 inches) in length with a wingspan of about 11 to 13 cm (4.3 to 5.1 inches) and weighing around 2.4 to 3.5 grams. The Rufous Hummingbird is slightly larger, ranging from 7.5 to 10 cm (3 to 4 inches) in length, with a wingspan near 12 to 15 cm (4.7 to 5.9 inches) and a weight of 3 to 4 grams.
Adult male Ruby-throated Hummingbirds are renowned for their brilliant iridescent ruby-red throat patch, or gorget, which can appear almost black in certain lighting due to light refraction. Their backs and heads are metallic green, and their underparts are white or pale gray. The tail is relatively short with a slight fork, and the outer tail feathers have white tips, which are visible during flight and perching.
Male Rufous Hummingbirds boast an equally dazzling but distinctly different appearance. Their throats and chests glow with a fiery orange-red gorget that extends further down the neck and chest compared to the Ruby-throated. Their backs and heads are a rich, warm rufous or coppery orange, earning the species its common name. Unlike the Ruby-throated, the Rufous has a more pointed tail with rufous-colored feathers edged in black, giving it a more angular silhouette.
Females of both species are more subtle in coloration and more challenging to identify. Female Ruby-throated Hummingbirds have green backs and white underparts, with a faintly spotted throat lacking the bright gorget of males. Female Rufous Hummingbirds differ by having green backs and crowns with rufous coloring on the flanks and tail feathers, which often have white tips. These subtle differences, along with behavioral clues, help ornithologists and birders differentiate between the two females.
Behavior & Diet
Both the Ruby-throated and Rufous Hummingbirds are known for their energetic and acrobatic flight, which includes hovering, darting, and even flying backward. They are highly territorial, especially males, who vigorously defend rich nectar sources during breeding and migration seasons. Their behavior is characterized by rapid wing beats — about 53 beats per second in the Ruby-throated and slightly faster in the Rufous — which generates the humming sound from which their name is derived.
Dietarily, both species primarily feed on nectar from a variety of flowering plants, using their long, specialized bills and extendable, brush-tipped tongues to extract the sugary liquid. Ruby-throated Hummingbirds favor tubular flowers such as bee balm, trumpet creeper, and jewelweed, while Rufous Hummingbirds are known to visit a range of flowers including columbines, penstemons, and paintbrushes. Both species supplement their nectar diet with small insects and spiders, which provide essential protein, vitamins, and minerals. According to RSPB, this species is well documented.
Interestingly, Rufous Hummingbirds are particularly aggressive feeders, often dominating smaller hummingbird species at feeding sites. Their feisty nature and territorial behavior can be observed as they chase off intruders at feeders or flowers. Ruby-throated Hummingbirds exhibit similar territoriality but tend to be more common in eastern gardens and woodlands, frequenting feeders filled with sugar water during migration and breeding seasons. According to eBird, this species is well documented.
Breeding & Reproduction
Both hummingbird species have fascinating breeding behaviors marked by elaborate courtship displays and meticulous nest construction. The Ruby-throated Hummingbird breeds across much of eastern North America from late April through early summer. Males perform aerial displays, including rapid dives and figure-eight maneuvers, to attract females. Nesting sites are typically found on horizontal tree branches, often in deciduous forests, and constructed by the female alone using soft materials like plant down, spider silk, and lichens, which provide flexibility and camouflage. The nests measure roughly 3 cm (1.2 inches) in diameter and accommodate two tiny white eggs, each about 1 cm long. Incubation lasts approximately 12 to 14 days, and fledging occurs about three weeks after hatching.
The Rufous Hummingbird’s breeding season occurs slightly earlier in some regions, starting in March or April, extending through summer, primarily in the Pacific Northwest and parts of the Rocky Mountains. Males also engage in impressive courtship displays involving steep dives and wing buzzing. Females build cup-shaped nests using similar materials, often on coniferous trees or shrubs. The nest size and egg characteristics closely resemble those of the Ruby-throated. Rufous Hummingbird chicks fledge within 18 to 22 days. Notably, Rufous Hummingbirds tend to have particularly high site fidelity, often returning to the same nesting areas year after year.
Conservation Status
Both the Ruby-throated and Rufous Hummingbirds currently enjoy stable population levels and are classified as Least Concern by the International Union for Conservation of Nature (IUCN). The Ruby-throated Hummingbird has a widespread and robust population estimated at several million individuals. Its adaptability to suburban and urban environments, where feeders and native flowering plants are abundant, contributes to its success.
The Rufous Hummingbird, while also plentiful, faces some regional challenges related to habitat loss, especially in breeding and stopover sites along its migratory route. Logging, urban development, and climate change threaten the availability of critical nectar sources and nesting habitats. However, conservation efforts focused on habitat preservation and planting native nectar-producing flowers have helped maintain healthy populations. Both species benefit from citizen science projects and backyard monitoring, which provide valuable data on migration timing and population trends.
Interesting Facts
Hummingbirds are among the smallest warm-blooded vertebrates, and the Ruby-throated and Rufous Hummingbirds exemplify this with their minuscule size yet incredible endurance. The Ruby-throated Hummingbird’s migratory journey is remarkable in that many individuals fly non-stop across the Gulf of Mexico—a distance of up to 800 kilometers (500 miles)—without stopping to feed. This feat requires immense energy reserves and precise navigation.
Rufous Hummingbirds are known for their relentless aggression despite their tiny size. They often dominate feeding territories against larger hummingbird species and can be seen chasing away intruders with fierce determination. Their boldness has earned them a reputation as the “feisty” hummingbird of the west.
Both species possess iridescent feathers, which create their vibrant throat patches through microscopic structures that refract light rather than pigments. This means their colors can shift dramatically depending on the angle of sunlight, making identification a challenge but also a delight for observers.
Finally, these hummingbirds play essential ecological roles as pollinators. By visiting flowers for nectar, they transfer pollen, aiding in the reproduction of numerous plant species, including wildflowers and cultivated crops. Supporting hummingbird populations through habitat conservation and planting native, nectar-rich flowers benefits entire ecosystems.
In summary, the Ruby-throated and Rufous Hummingbirds, while similar in many ways, are distinct species with unique adaptations, behaviors, and ranges. Appreciating their differences enhances our understanding of North America’s avian diversity and deepens the enjoyment of observing these jewel-like birds in the wild or backyard gardens.
