Ornithology Study Guide PDF

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Ornithology Study Guide ...

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Ornithology Study Guide – Test 1 Lab Feathers o

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Feather Structure  Feathers are keratinized outgrowths of the skin  Develop from follicles just the hairs of mammals  Feathers probably evolved from scales  Most important functions of feathers:  Provide insulation  Reduces loss of body heat  Allow for flight  Streamlining contour on body  Increases surface area of the wings and tail  Concealment with coloration  Display Parts of a feather:  Shaf – axis or tube of the feather  Two parts:  Calamus – lower part of the shaf that inserts into the skin o Does not have vanes o Hollow and somewhat transparent; basal end is tapered o Inferior umbilicus is the end of the calamus and is where the feather receives nutrient pulp during its growth. Once it is fully grown it is covered by a horny plate o The superior umbilicus is at the distal end of the calamus and is a small opening that faces towards the body of the bird when the wing is closed, between the point where the vanes begin. It is the remnant of the open, upper end of the tube of epidermis in a growing feather. o The cortex covers the calamus  Rachis – distal part of the shaf that supports the vanes o Flexible from side to side but stiff dorso-ventrally.  Septa present in the medulla along with the longitudinal grove on the ventral surface gives primary feathers flexibility and stiffness o Is a continuation of the feather tube above the dorsal side of the calamus o Spans from the superior umbilicus to the tip of the feather o Quadrangular in cross section o Two layers:  Outer cortex – thin and transparent, has ridges projecting from the dorsal surface

Inner medulla – comprised of pithy tissue that is firm and opaque o Ventral side of rachis has external pulp caps that extend through the superior umbilicus. These caps used to extend to the tip of the feather, seen when looking at the rachis longitudinally; there is a groove present with a ventral ridge on each side Vanes – two; one on each side of rachis o Outer vane – leading edge; narrower o Each vane is made up of a series of flattened, parallel plates whose end slope toward the distal end of the feather o Proximal part of each vane is rather downy 

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Two kinds of feathers:  Pennaceous feathers  Flight feathers  Have vanes where the barbules coming off the rachis interlock and form semi solid structures  When birds are preening they relock barbules  Calamus is the extension of the rachis that sticks into skin  Form the general outline of the bird – contour feathers  Flight feathers have asymmetrical vanes with the leading edge being more narrow  Contour feathers have symmetrical vanes o Have a plumulaceous base and a pennaceous tip  Plumulaceous feathers  Barbs do not interlock  Trap air to insulate  Rachis is absent or very small Aferfeathers  Rare on adult pigeons Semiplumes  Plumulaceous feathers that have a rachis  Found on egrets Downy  Plumulaceous  Not much of a rachis if any

Primaries  Primaries attach to carpometacarpus  Usually have I – X and are numbered in the order that they molt  As primary I is re-growing primary 2 will molt, etc so the bird isn’t flightless

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Secondaries  attached to ulna  also counted from the inside out in order of molt sequence Coverts lay over the base of the flight feathers and form the shape of the wings Scapulars are attached at the shoulder...