Birds Of A Feather: Mexican Bird(s) Of The Month, Two Hummingbirds

By Dennis Taylor

Hummingbirds, comprising the Trochilidae family, are native to the Americas. Around 360 to 375 species grouped into nine subgroups can be found from Alaska to Tierra del Fuego, but most are located in Central and South America. The Broad-billed and the Violet-crowned hummingbirds, are what I like to call our little jewels.  Although México is blessed with at least sixty different species of hummingbirds, only these two stay with us year-round. Eight others make occasional showings around San Miguel.

The Broad-billed hummingbird (Cynanthus latirostris) is a member of the emerald subgroup, and their range covers almost the entire west coast and western central regions north of México City up to the US border.  The male is a gorgeous little fellow, sporting iridescent emerald-green feathers on his back and sides, with dark blue throat and tail feathers.  Females are similar, but with less intense throat colors.  As their name implies, these birds have distinctive, broad, bright-red bills tipped in black.  They are one of the smaller hummingbirds, 3-4 inches long (including bill) and weighing a mere 3-4 grams (i.e.- less than the weight of a nickel).

The Violet-crowned hummingbird (Ramosomyia violiceps) is also a member of the emerald subgroup. They are somewhat larger than the broad-bills, averaging 4 to 4.5  inches in length and weighing 5 to 5.8 grams. Adult males have an intense violet-blue crown, a bluish violet hindneck, and dull grayish brown to greenish brown back and rump. Their tail is coppery bronze while their underside, from throat to undertail coverts, is pure white with light olive green flanks. Their pure white breast is quite distinctive, and makes them easy to spot.  Females are similarly colored, although in somewhat duller tones.

Both species feed on nectar from flowers and smaller insects. The range of these two hummingbirds overlaps, and hybrids between them have been seen. When food sources are abundant, the two get along, but where scarce, violet-crowned hummingbirds defend preferred flower patches, forcing the broad-billed hummingbirds to choose flowers that provide less energy. Aside from their distinction as the world’s smallest birds, hummingbirds are characterised by an extensive list of superlatives. The Bee hummingbird of Cuba, for example, is the smallest of all; only 2 to 2 ½ inches long, and weighing 2 to 2.6 grams, about the weight of a dime.

Hummingbirds are masters of hovering. Their unique wing structure and flexible shoulder joints allows them to rotate their wings in a figure-eight pattern. This motion generates lift on both the forward and backward strokes of the wing, enabling them to remain suspended in one spot with incredible stability. They use this ability to sip nectar from flowers that are not sturdy enough to perch on. While some other birds can hover briefly, none can do so for prolonged periods. To sustain such rapid wingbeats during flight and hovering, hummingbirds use the human equivalent of 150,000 calories per day.  You would need to consume 260 Big Macs per day to match a hummingbird’s daily caloric needs, an amount estimated to be 10 times the energy utilized by a marathon runner in competition. Hummingbirds are rare among vertebrates in their ability to rapidly make use of ingested sugars to fuel their energetically expensive hovering flight.  Hummingbirds and the plants they visit for nectar have coevolved. Called the plant-bird syndrome, it has resulted in some hummingbird species developing unusual bill shapes that correlate with the contours of the flowers they depend on for nectar.

The wings of typical hummingbirds beat up to 80 times per second.  No wonder their wings are only a blur when in flight.  Their heart rate can reach as high as 1,260 beats per minute, with a breathing rate of 250 breaths per minute at rest.  The average heart rate for a person is between 60 to 100 beats per minute. In flight, hummingbirds can attain speeds of up to 34 mph, and some male species engage in courtship dives at speeds up to 51 mph.

Hummingbirds have unusually long lifespans for organisms with such rapid metabolisms, with some living for a decade or more. For comparison, shrews, among the smallest of all mammals, seldom live longer than 2 years. The longest recorded lifespan of a hummingbird in the wild was a female broad-tailed hummingbird that was banded as an adult at about one year of age, then recaptured 11 years later, making her at least 12 years old.