This week for Flora and Fauna Friday we have an unmistakably minuscule acrobatic busybody, the Ruby-throated Hummingbird (Archilochus colubris).
The Ruby-throated Hummingbird is our only species of Hummingbird that appears with any regularity in South Carolina. They are our smallest bird, weighing only a few grams at adulthood. This unrivaled smallness gives them many advantages, as well as handicaps, that I’ll touch on later. Our Hummingbird has a pointed head drawing into a long, narrow bill. Their stubby wide tail, short triangular wings, and itty-bitty delicate legs give them quite a dainty appearance. Both sexes are a dusty white beneath with a verdant green back that sparkles with iridescence. Females are drabber with a white throat, tail-feather tips, and cheeks. Males possess a black eye-stripe that flows atop their jowls and onto a hot stoked-coal throat that smolders in the light like a winter sunset.
Ruby-throated Hummingbirds are common throughout the state wherever ample food can be found. They are specialized to drink nectar and can only survive where there are sufficient nectar plants to sustain them. Many plants have specialized their flowers to encourage Hummingbird visitation. Plants such as Crossvine, Coralbean, Trumpet Vine, and Red Buckeye. The pollen bearing structures and nectar glands of these flowers are positioned so as to maximize Hummingbird interaction. These plants are certainly favorites but Hummingbirds will take anything they can get. They will readily feed from any flower that produces sufficient nectar, including many exotic and ornamental plants like Manettia and Zinnia. Yet, they do have a clear preference for red flowers. Hummingbirds are not afraid to accept handouts either and will stake a claim to a properly stocked hummingbird feeder. (On an aside, do not use dyed hummingbird feed in your feeder. The dye is unnecessary and potentially toxic to the birds. Plain sugar water is best.) In addition to nectar, Hummingbirds will eat small insects and spiders. They also drink from sap wells created by Yellow-bellied Sapsuckers. These birds are quite feisty despite their stature and spend a good deal of time fussing and fighting over flowers.
Hummingbird habitat is so dependent of food availability because the birds have a ludicrously high metabolism. Their heart rate can exceed 1200 beats per minute and they consume an obscene amount of calories just to stay alive. Due to their small size, their metabolism must compensate to keep their core body temperature high enough. Their small size also means they can’t store much extra energy as body fat. So the birds must eat constantly or they’ll soon starve to death. So why do these birds want to be so small? The answer to that is what makes Hummingbirds so unique.
Hummingbirds are the most agile vertebrate on the planet. They have the ability to fly three dimensionally. They can move up, down, left, right, forward, or backward in any combination of those axes. They can fly at 25mph or hover stationary in mid-air. Their small size, along with some unique physiological adaptations, make all this possible. Their wings beat dozens of times a second, allowing for extremely rapid and fine flight control. This maneuverability allows these birds to access food sources, mainly treetop flowers, which were practically inaccessible to anything but insects before. Feeding in flight and not perching to feed reduced their risk of predation as well.
