Cool and Weird Birds With a Swirly Eye to Draw
All About Feathers
Unique to birds and their dinosaur ancestors, feathers have evolved into impressive biological structures that come in a surprising variety of colors and forms. Here, nosotros cover the latitude of feather biology by looking at feathers from a diversity of scientific viewpoints including their anatomy, part, evolution, and development.
From the fluffy down on a swan chick to the brilliant spiral on a Rex Bird-of-Paradise tail, feathers are remarkable not simply in the way they look to the naked eye, merely also for their intricate microstructure. Agreement feather anatomy at the microscopic level provides insight into how feathers function. For case, the interlocking Velcro-like construction on many bird feathers creates the polish, flexible, and resilient surface that supports flight and sheds water.
Every bit feathers grow, they mature into highly branched structures. Conscientious study of this procedure inspired new hypotheses hypothesisan explanation that is testable through study and experimentation virtually the evolution of feathers through stages of increasing complication. Newly unearthed dinosaur fossils from China and Canada take supported these hypotheses by providing specimens from each phase in the proposed evolutionary history—a clear example of how investigating biological structures beyond contexts tin create scientific breakthroughs.
Feather Science From Many Angles
Thorough understanding of biological structures like feathers requires exam from many angles. We now recognize that how feathers function is intricately connected to how they're structured, and how they grow is closely linked to how they evolved.
Niko Tinbergen, a 1973 Nobel Prize winner for his work to understand animal beliefs, developed what he called the iv levels of assay that biologists have been using always since to structure their research. For us to fully understand anything in nature, he said, we need to retrieve about these 4 questions:
- How does it work? (machinery)
- How does it function? (adaptation)
- How does it develop? (development)
- How did it evolve? (development)
Here we accept taken Tinbergen's communication and explored each of these questions to requite y'all a comprehensive understanding of feather biology.
Feather Anatomy: How Exercise Feathers Piece of work?
Feather structure
Although feathers come in an incredible multifariousness of forms, they are all composed of the poly peptide beta-keratin and fabricated upwards of the same basic parts, arranged in a branching structure. In the most complex feathers, the calamus calamus<bridge class="phonetic">CAL-a-muss</span>the hollow barbless base of operations of a plume's stiff primal shaft extends into a fundamental rachis rachis<bridge class="phonetic">RAY-kiss</span>the stiff primal shaft of a plume from which barbs branch which branches into barbs barbone of the main branches off the primal shaft of a feather, and so into barbules barbule<span class="phonetic">barb-YOOL</span>i of the secondary branches off a feather affront with small hooks that interlock with nearby barbules. The variety in feathers comes from the evolution of small modifications in this basic branching structure to serve unlike functions.
Downy feathers look fluffy because they have a loosely bundled plumulaceous plumulaceous<bridge form="phonetic">ploom-yoo-LAY-shuss</bridge>having a loose, not-interlocking feather structure microstructure with flexible barbs and relatively long barbules that trap air shut to the bird'southward warm body. Pennaceous pennaceous<span class="phonetic">pen-AY-shuss</bridge>having an interlocking plume structure that creates a polish surface, or vane feathers are stiff and more often than not flat, a large divergence that comes from a small amending in construction; microscopic hooks on the barbules that interlock to grade a wind and waterproof bulwark that allows birds to fly and stay dry. Many feathers have both fluffy plumulaceous regions and more structured pennaceous regions.
Feather types
Feathers autumn into ane of seven broad categories based on their structure and location on the bird'south body.
Fly feathers
The wing feathers specialized for flight are characterized past compatible windproof surfaces, or vanes, on either side of the central shaft that are created by an interlocking microstructure. Besides chosen remiges remiges REM-i-jeezthe flight feathers on the wing that are fastened to os rather than merely to skin, these feathers are disproportionate with a shorter, less flexible leading edge that prevents midair twisting.
Tail feathers
Most tail feathers, or rectrices rectrices RECT-ri-seestail feathers, feature an interlocking microstructure similar to wing feathers. Arranged in a fan shape, these feathers back up precision steering in flight. Typically, birds have six pairs of feathers on the tail, which display increasing levels of asymmetry toward the outer pairs. In some birds, tail feathers have evolved into showy ornaments that are useless in flight.
Contour feathers
Contour feathers are what you run across roofing the bird's torso and streamlining its shape. Arranged in an overlapping pattern like shingles, the waterproof tips are exposed to the elements and the fluffy bases are tucked close to the body. Sometimes brilliantly colored or uniformly drab, contour feathers tin can likewise help the bird show off or stay camouflaged. Profile feathers on the wing, called coverts coverts COH-vertsoverlapping feathers that shape the wing into an efficient airfoil, shape it into an efficient airfoil airfoilwinglike construction that produces lift and drag as information technology moves through the air by smoothing over the region where the flight feathers adhere to the bone.
Semiplume
More often than not subconscious beneath other feathers on the body, semiplumes have a developed central rachis but no hooks on the barbules, creating a fluffy insulating construction.
Downward
Similar to semiplumes with an even looser branching construction simply petty or no central rachis, down feathers are relatively brusque and positioned closest to the torso where they trap body heat.
Filoplume
Short uncomplicated feathers with few barbs, filoplumes function like mammal whiskers to sense the position of the contour feathers.
Bristle
Bristles are the simplest feathers, with a stiff rachis that usually lacks barb branches. Almost ordinarily found on the caput, beard may protect the bird's eyes and face up.
Further Learning
Download the accompanying Blithe Slide set.
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Learn more about feather beefcake and peek at microscopic feather structure.
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Feather Function: What do feathers practice?
Each feather on a bird's body is a finely tuned structure that serves an important role in the bird's activities. Feathers let birds to fly, but they as well help them testify off, blend in, stay warm, and keep dry. Some feathers evolved as specialized airfoil airfoilwinglike construction that produces elevator and drag every bit it moves through the air for efficient flying. Others have been shaped into farthermost ornamental forms that create impressive displays but may even hinder mobility. Often we can readily tell how a feather functions, just sometimes the role of a plume is mysterious and we need a scientific report to fill in the picture.
Flight
The primary and secondary wing feathers, or remiges remiges REM-i-jeezthe flight feathers on the wing that are attached to os rather than just to pare, permit birds to accept to the skies. Unlike other feathers, remiges are anchored to os with stiff ligaments ligamentband of tissue that connects a os to another os, piece of cartilage, or plume so they can withstand the demands of flight and be precisely positioned. The primaries principalane of the feathers occupying the outer half of the wing that can be controlled to generate forward thrust during flying are longest of the flight feathers. They occupy the outer one-half of the wing, tin can exist controlled and rotated like rigid fingers, and provide nigh of the bird'due south frontward thrust. While secondaries secondaryone of the feathers occupying the inner one-half of the wing that overlap with other secondaries to form an airfoil that provides lift during flight cannot be controlled as extensively, they provide most of the lift by overlapping to course an efficient airfoil airfoilwinglike construction that produces lift and drag as information technology moves through the air. Tail feathers, or rectrices rectrices RECT-ri-seestail feathers, are besides classified as flight feathers. They are essential for steering, merely only the two most primal feathers adhere to os.
Brandish
Some feathers are so highly modified for display that they most don't look like feathers at all. For instance, the iridescent spiral from a Male monarch Bird-of-Paradise (Cicinnurus regius) tail functions as an ornamentation in the male person'south courtship display. Structurally, the feather is bizarre, with a bare rachis rachis RAY-kissthe stiff central shaft of a feather from which barbs co-operative that ends in a tight screw of barbs barbane of the main branches off the central shaft of a feather and barbules barbule barb-YOOLone of the secondary branches off a feather affront arranged only on one side of the rachis to form an eye-catching brilliant medallion.
Modified contour feathers on the head are likewise usually used in courtship displays. For example, the male person Wood Duck's (Aix sponsa) crest forms a colorful fan that completely changes its caput shape. During this transformation, the bird elevates thousands of tiny feathers in unison past manipulating muscles just under the pare.
Not all fancy feathers are used to woo a partner; some are used in displays of aggression. For instance, Bluish Jays (Cyanocitta cristata) keep their crests lowered when they are at rest or with family unit and flock members, but raise them during ambitious interactions.
The drab contour feathers covering the trunk of some birds may seem lackluster, merely subtle brownish patterns can create an impressive degree of camouflage in forested environments. Famous for hiding in apparently sight, the Common Potoo (Nyctibius griseus) is covered with feathers that mimic the colors of the tree branches information technology perches on. Adding to the disguise, the potoo will adjust its posture and close its eyes into tiny slits, making itself announced to be an extension of the tree.
Not all camouflage has to exist drab. For example, the vibrant green contour feathers of male person Eclectus Parrots (Eclectus roratus) serve a camouflage function during foraging trips in the rainforest canopy. Dorsum at the nest cavity where the dark-green stands out confronting the brown tree bark, the male coloration aids in the intense competition with other males to win female person mates. Male Eclectus Parrots likely evolved their green coloration as a tradeoff between effective camouflage and display. This is a rare example of feathers that allow birds to both hibernate and evidence off.1
Insulation
Have y'all ever wondered why some birds hatch naked while others are covered in a coat of fuzzy feathers? Many immature water birds must be able to swim and provender alongside their parents well-nigh immediately after hatching. These precocial precocial pree-KO-shuldescribing a chick that is mobile speedily afterward hatching and requires little parental care chicks hatch with a full coat of natal down to keep them warm in cold h2o. Immature Mute Swans (Cygnus olor) for example, hatch with a fuzzy coat of natal downwards and afterwards a few weeks, replace the natal down with an inner layer of developed downwardly and an outer coat of profile feathers. In contrast, the young of many songbirds are built-in completely naked.
These altricial altricial Al-TRISH-uldescribing a chick that is unable to walk, fly, or swim soon after hatching and requires parental care for an extended period species stay warm by arresting heat from attention parents and huddling together in an insulated nest. Utterly dependent at hatch, altricial species, like Purple Martins (Progne subis), crave lots of parental care.
Weatherproofing
Arranged in an overlapping pattern on a bird's body to betrayal the waterproof tips, contour feathers let water to scroll right off a bird's back. Birds constantly maintain their waterproof coat through extensive grooming, or preening preenusing the beak to maintain the wellness and structure of feathers to ensure that every feather is in practiced shape. The interlocking structure is and so important that any disruption to information technology—such every bit if spilled oil coats the feathers—leaves the bird waterlogged and helpless. For ducks and birds like the Common Loon (Gavia immer) that spend virtually of their time in the water, maintaining a waterproof glaze is disquisitional for survival.
All the same a mystery
Some feather functions remain a mystery. The plumage tufts on the heads of Smashing Horned Owls (Bubo virginianus) are frequently mistaken for ears. These modified contour feathers are completely split up from the ear and do not help owls hear, yet there is no scientific consensus on the function of these tufts. Some have proposed that the horns are for brandish. Others have suggested that owls use them for more complete camouflage while roosting in daylight, but other functions are also possible and no ane has yet done a detailed study to find out.two
Farther Learning
Explore photographs of some intriguing feathers and guess their function to reveal the full story.
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Feather Growth: How do feathers develop?
Feathers are dead structures that cannot repair themselves when damaged. Because a healthy and functional glaze is disquisitional to survival, each yr birds shed their old feathers and so abound a whole new ready. This molting moltin birds, the process of losing and regrowing feathers on a regular cycle process is a carefully timed affair in which feathers are shed and regenerate in turn over a period of weeks so the bird can maintain its protective outer layer and power to fly. In one case the new set of feathers has matured, molt is complete and new growth only occurs before the next molt bike when feathers are accidentally lost.
The growth process
A close look at feather growth reveals how these intricate structures course.
- Each new feather grows from a small outgrowth of skin called the papilla.
- As feathers mature, their tips get pushed away from the papilla, where the newest parts of the feather course. Like human hair, feathers are youngest at their base of operations.
- The plumage's structure develops as proteins are laid down around the surface of this bump of pare. It'due south here that the branching patterns form by smaller branches fusing at the base to make thicker ones—barbules barbule barb-YOOLone of the secondary branches off a feather affront fuse into barbs barbi of the main branches off the central shaft of a feather and barbs fuse into a rachis rachis RAY-kissthe strong key shaft of a feather from which barbs branch.
- As the feather grows, it stays curled in a tubular shape effectually the papilla until it is pushed abroad from the growth area.
- A protective sheath maintains the feather's cylindrical shape until it starts to disintegrate near the tip, allowing the mature role of the plume to unfurl.
- The sheath falls off and the growth process is consummate.
Once the feather unfurls, its interlocking structure is fully formed. Throughout the twelvemonth, the bird maintains its mature feathers through regular care, or preening preenusing the beak to maintain the wellness and construction of feathers. Whenever the barbules barbule affront-YOOLone of the secondary branches off a feather barb become disturbed, the bird uses its beak to carefully guide them back into place. By the following molt season, many of the bird's feathers have experienced enough vesture and tear that preening can no longer maintain their structure. Fortunately, during molt the bird grows a completely new ready.
Further Learning
Download the accompanying Animated Slide gear up.
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Plumage Development: How did feathers evolve?
Flight feathers, with their intricate microstructure, are impressive examples of natural applied science. But how did they evolve? From the fossil record, we know that birds evolved from dinosaurs, some of which had feathers. But those offset feathers had nothing to do with flight—they probably helped dinosaurs show off.
Scientists recently worked out a hypothesis hypothesisan explanation that is testable through study and experimentation to explain how flight feathers could have evolved.3 They probably began as uncomplicated tufts, and so gradually developed through stages of increasing complexity into interlocking structures capable of supporting flight.
Evolutionary stages
ane. The earliest feather was a simple hollow tube.
2. The elementary tube evolved into a cluster of barbs affronti of the main branches off the central shaft of a feather.
3. (a) The base of the barbs fused together to form a fundamental rachis rachis RAY-kissthe stiff central shaft of a feather from which barbs branchand (b) barbules barbule affront-YOOLane of the secondary branches off a feather barb branched from the barbs, as nosotros see in modern-day down feathers.
iv. The barbules evolved hooks that interlock to make flat vanes as in current contour feathers.
5. The plumage structure evolved asymmetry with the aerodynamic properties of mod-day flight feathers.
Fossil evidence recently unearthed in Red china and Canada has confirmed that bird ancestors did indeed possess feathers from each of the steps in this proposed evolutionary pathway. Surprisingly, many theropod theropod THAIR-o-podbelonging to a bipedal subgroup of dinosaurs from which birds likely evolved dinosaurs had unproblematic stage 1 feathers covering their bodies. This "dino fuzz" even covered close relatives of the great Tyrannosaurus king. These early feathers may have been insulating, or when colorful, may have helped dinosaurs testify off or stay camouflaged. In that location is likewise intriguing testify of more than circuitous Phase 3 and four feathers from finds like Ornithomimus edmontonicus. Every bit adults, these big, bulky creatures sported feathers arranged forth fly-like structures, simply no wing plumage traces take been found among the juvenile specimens. This suggests that even as dinosaurs started to evolve wings, the wing feathers were likely used for courtship or territorial brandish, non flight.4
Though it may take time for people to get used to the thought of fuzzy or elaborately plumed meat-eating dinosaurs, this scientific breakthrough reminds us that asking questions from multiple perspectives helps generate new testable hypotheses hypothesisan explanation that is testable through study and experimentation and scientific knowledge. For this reason, it is becoming more than and more common for scientists to piece of work across disciplines. In fact, the agile field of evolutionary-developmental biology evolutionary-developmental biology (evo-devo)a field of biology that investigates the human relationship between an organism's development and its evolutionary origins ("evo-devo") focuses on discovering a construction'due south evolutionary past by observing its process of growth and evolution.
Farther Learning
Navigate a cartoon about feather growth and development to learn more than most how "dino fuzz" evolved into elegant flight feathers
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Studying Feathers: How practice scientists use Tinbergen'southward iv questions?
We've just used Tinbergen'south arroyo to expect at feathers from several different perspectives—but it's not just a learning exercise. Scientists similar those in the evo-devo oversupply, are making discoveries in just the aforementioned way, by linking findings from beyond the biological disciplines.
One such scientist is Kim Bostwick, who used this integrated approach to untangle the mysteries of a bird whose feathers work like a musical instrument. This may sound like an outrageous idea, simply male Lodge-winged Manakins of Cardinal and South America apply a highly modified feather structure to play a powerful i-notation melody. Strong evolutionary pressure on these males to attract females has made them unique in the bird world, but it took years of scientific investigation past Bostwick and colleagues to work out the full story of how and why these birds sing with their wings.
Singing wings
So how do they do information technology? Order-winged Manakins sing with their wings by rubbing specialized feathers together. 1 of these feathers is club-shaped with ridges along its edge. The adjacent feather is slender, and bent at a 45-degree bending. This bent plume acts every bit a option, while its ridged analogue acts as a rummage to produce a 1-note vocal. This method of producing sound is chosen stridulation stridulation<span grade="phonetic">stri-du-LAY-<br>shun</span>the act of rubbing together body parts to brand a sound and also occurs in insects, such as crickets.
Kim's story
Kim Bostwick began her study of Club-winged Manakins by request questions almost how they sing with their wings. She spent years piecing together how the birds accomplish this feat mechanically, but she did not stop there. Considering Kim had ever been interested in evolution, she also asked questions near how their specialized feathers and associated behaviors evolved. This led her to study other birds closely related to Club-winged Manakins to see what behavioral innovations occurred in their evolutionary history that contributed to the brandish we see today. It turns out that the behavior evolved through a series of small steps, including short wing clicks and backwards hopping, into ane of the most unusual displays in the animal globe. Similar Niko Tinbergen, Kim is one of the many scientists who prefer to ask scientific questions from many angles, going beyond the mechanics to brand discoveries near office, evolution, and evolution.
To acquire more about Kim'south story at the Singing Wings website.
Farther Learning
Scout a five-function video on the Club winged Manakin.
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References
1. Heinsohn, R., Legge, S., & Endler, J. A. (2005). Extreme reversed sexual dichromatism in a bird without sex role reversal. Science. 309(5734), 617–ix.
ii. Perrone, 1000. (1981). Adaptive significance of ear tufts in owls. The Condor, 83(4), 383.
three. Prum, R. O., & Brush, A. H. (2002). The evolutionary origin and diversification of feathers. The Quarterly Review of Biological science, 77(3), 261–295.
4. Zelenitsky, D. K., Therrien, F., Erickson, K. M., DeBuhr, C. Fifty., Kobayashi, Y., Eberth, D. A., & Hadfield, F. (2012). Feathered non-avian dinosaurs from North America provide insight into wing origins. Science. 338(6106), 510–four.
Suggested citation: Cornell Lab of Ornithology. 2013. All About Feathers. All Nigh Bird Biological science <birdbiology.org>. Cornell Lab of Ornithology, Ithaca, New York. < add together date accessed here: eastward.g. 02 Oct. 2013 >.
Acknowledgements:
Author: Mya Thompson
Spider web Designer: Jeff Szuc
Web programmer: Tahir Poduska
Illustrator: Andrew Leach
Content assistants: Marie Russell, Feven Asefaha
Source: https://academy.allaboutbirds.org/feathers-article/
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