Types of Feathers.pptx

Types of Feathers

1. Advanced Ornithology by Maryam R iasat TYPES OF FEATHERS

2. Feathers fall into following broad categories based on their structure and location on the bird’s body Vaned f eathers Contour feathers Wing feathers Tail feathers Semiplume Filoplume Down Bristle

3. Vaned feathers The most conspicuous feathers are called vaned feathers They include the smaller contour feathers that cover the body surface and the larger flight feathers of the wings and tail The smooth overlapping arrangement of vaned feathers reduces air turbulence in flight The tiny, flat contour feathers that cover a penguin’s body create a smooth, almost scaly, surface reduces friction during swimming

4. Wing feathers The flight feathers of the wing, called remiges are large and stiff pennnceous feathers They primarily serve aerodynamic functions and have little importance in insulation Rows of smaller feathers, called coverts, overlap the bases of the remiges and cover the gaps between them to reduce air turbulance Coverts assists in flight

5. Primaries The long shafts of the outer (distal) remiges are called as primaries Primaries are attach to the bones of the hand and the second digit These feathers provide forward thrust on the downstroke of the wing during flight Most birds have 10 primaries but the number can variate from 1 to10

6. Secondaries The inner (proximal) flight feathers of the wing are called as secondaries S econdaries are attach to the ulna wing bone Numbering vary from 6 to 19 In some species, they have been modified for display purposes, essential for courtship

7. Tail feathers The flight feathers of the tail, called rectrices Rectrices are attach to the fused caudal vertebrae, or pygostyle The usual 12 rectrices function primarily in steering and braking during flight Numbering vary from 12 to 24

8. Rectrices vary from thin and flexible, like those in the display tail feathers of some hummingbirds to stiff rods, like those of the bracing tail feathers of woodpeckers

9. Down Unlike firm- vaned feathers, down ( plumulaceous ) feathers are soft and fluffy i.e. feathers of chicks Down feathers provide excellent natural thermal insulation A down feather typically lacks a rachis except few birds i.e. waterfowl Down feathers also lack hooked barbules On most birds, flexible plumulaceous barbs and barbules extend directly and loosely from the basal calamus Downy barbules entangle loosely, trapping air in an insulating layer next to the skin

10. Semiplume Semiplumes are intermediate in structure between down and contour feathers They enhance insulation, fill out the aerodynamic contours of body plumage, and serve as courtship ornaments A semiplume has a large rachis with loose plumulaceous vanes Some are close to down in structure, whereas others more closely resemble contour feathers

11. Semiplumes are located between the contour feathers and are usually hidden from view at the edges of the contour feather tracts Semiplumes are distinguished from down feathers by the length of their rachises, which are always longer than the longest barb

12. Filoplume Filoplumes  are very small hairlike feathers Contain a rachis and only a few sparse barbs at the tip A fine shaft, or rachis, thickens distally, ending in a terminal tuft of one to six short barbs with barbules Distributed inconspicuously throughout the plumage, they are most numerous near mechanically active or movable feathers Each flight feather may have from 8 to 12 filoplumes

13. They extend beyond the contour feathers of songbirds, particularly on the back of the neck, a region called the nape Filoplumes provide sensory information pertaining to temperature, wind speed, and feather movements needed for birds to fly efficiently Disturbance of a filoplume’s enlarged tip is magnified and transmitted by the long, thin shaft to sensory corpuscles at its base, which then signal the muscles at the base to adjust the feather’s position

14. Filoplumes associated with the flight feathers aid aerodynamic adjustments Filoplumes association with contour feathers help to monitor airspeed Filophimes are absent in penguins and in flightless birds such as ostriches

15. Bristle Bristles are specialized feathers with both sensory and protective functions Bristles are simplified feathers that consist only of a stiff, tapered rachis with a few basal barbs Bristles are found almost exclusively on the heads of birds They can located around the eyes and beak of a birds Most aerial insect eating birds have bristles and around their mouths Bristle feathers are also believed to be sensory in nature