PEEC Amateur Naturalist: What Are Feathers Used For?

 Picture 1: Fiery-throated Hummingbird. Photo by Joseph Pescatore 

PEEC Amateur Naturalist: What are Feathers Used for?
By Robert Dryja
Summer now is at its peak and so is the population of hummingbirds. Some of us may be refilling our hummingbird feeders twice a day and have up to eight hummingbirds arriving at the same time to feed. Hummingbirds are observant and learn where to go for a meal at any time of day. They also may loose their shyness, circling within inches of a person who is refilling a feeder. Some will even land on a person’s hand for a sip of sugar water.
This is therefore a good time to observe the many ways that feathers are used, considering the  hummingbird as our model. Picture 1 is the starting point. The body, wing and tail feathers are all positioned in straight lines, reminding us of the way airplanes are made.
Picture 2 shows that a hummingbird can be much more flexible in its use of its feathers compared to an airplane. The wing feathers now are bent along two curves. The length of the wing curves upwards while the individual feathers on it curve downwards. The individual tail feathers are spread to be about twice as wide as the body when compared to Picture 1.
Picture 3 shows this flexibility taken even further. The hummingbird now is twisting its whole body so that all of its tail feathers are moved to one side. It now appears to be dancing as much as flying. A hummingbird flies by controlling the position of its individual feathers and the overall shape of its body. This positioning can be changed in fractions of a second.
Feathers are used for advertising  as well as flying. The white, black and orange color pattern stands out for the tail feathers of a  Broad-tailed hummingbird. The green irridescence on its back and its dark wings further help. A rosy red-irridescence is present around the throat of the males, (see Picture 1). A female Broad-tailed hummingbird in contrast has a speckled white colored throat area, (see Picure 5).
A hummingbird may be clearly visible when it is out the open. It iridescent colors in sunlight make it more outstanding. However this situation changes when it sits quietly on a branch of a bush or tree. It is now camouflaged due to its small size and its green or dark coloration. Can you easily see the hummingbird in Picture 6A?
Feathers have evolved for temperature insulation as well as for flying. The nest of a hummingbird is padded with down feathers. The padding is about a fourth-inch thick and sufficient to keep the incubating eggs warm throughout a night while a parent is sitting on top of them. An adult bird may fluff its feathers so that is more insulated. Fluffing involves spreading feathers apart so that more small air spaces are created.
The insulating effectiveness of feathers can be too much on warm days. How can a hummingbird keep from overheating when it covered with feathers? More blood flows to their eyes, feet, and under their wing pits so that more body heat can escape via those areas that have fewer insulating feathers. An infrared video is available to watch at:
Feathers also are used to create specific kinds of sounds. Male Broad-tailed hummingbirds create a trilling sound with their wings while flying. An audio recording can be heard at the Audubon website.
Look for the audio link at the lower right side of the page:
Owls have had their feathers evolve in the opposite direction. Their feathers do not produce sound while they are flying. The silence helps owls since their prey cannot hear them coming.
Feathers therefore are used to distinguish between males and females, display and camouflage, temperature control, and sound manipulation. These are in addition to the aerodynamics of flying in which there are five kinds of feathers in use.
Picture 2: A male Broad-tailed hummingbird with it body and its feathers positioned in straight lines. Photo by Bob Walker
Picture 3: A Black-chinned hummingbird with its wing feathers curved and its tail feathers spread apart. Photo by Bob Walker
Picture 4: A female Broad-tailed hummingbird twists its body as well as changes the shape and position of its feathers while flying. Is it dancing as well as flying? Photo by Bob Walker
Picture 5: A Broad-tailed hummingbird advertising itself with the color of its feathers. Photo by Bob Walker
Picture 6: A female Broad-tailed hummingbird showing its speckled white throat area. Photo by Bob Walker
Picture 7: Where is that hummingbird? Photo by Robert Dryja
Picture 8: Ah, there it is, to the left side of a peach. Photo by Robert Dryja
Picture 9: A female Broad-tailed hummingbird sitting on its insulated nest. Note that the nest is camouflaged to match the color and texture of the branch it is built upon. Photo by Bob Walker
Picture 10: A Rufous hummingbird fluffing its feathers to provide more insulation for itself. Photo by Bob walker
Picture 11: A Calliope hummingbird cools itself by extending its feet. Photo by Bob Walker
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