Aves (birds) Flashcards
TRUE or FALSE: Birds are endothermic
TRUE
What are the three parts of a feather?
Calamus: tubular base
Rachis: long, tapering solid shaft
Barbs: side branches that project from the rachis
What are the five types of feathers?
Contour: flight feathers of the wing/tail, form protective layer of outer plumage
Down: no rachis, loose bundles of filament for insulation
Semiplume: intermediate between contour and down feathers
Bristles: lack barbs or are greatly reduced
Filoplumes: flexible and rod like, few barbs at tips, sense the movement of other feathers around them (proprioception)
What are some other general features of birds?
Have beaks rather than teeth, usually fly, modified upper fenestra and lower mandibular fenestra, lower temporal fenestra joined with the eye, finger are fused or partially fused together to allow for rigidity, keeled sternum for flight muscles to attach to, vertebral ribs of the trunk carry uncinate processes made of bones, short tail with pygostyle, air filled pneumatic sacs pervading much of their bodies (a lot of skeleton), lung with unidirectional air flow
What is post-cranial pneumaticity in birds? How is this different from in tetrapods?
In typical tetrapods their bones contain internal spaces filled with marrow (combo of fat and blood producing tissue) and bones also may contain internal pneumatic spaces that represent air filled sacs branching from the respiratory tract.
In birds, their post cranial pneumaticity is formed by soft tissues of the pneumatic sacs invading into the internal spaces of the bones, and this is related to the pneumatic sacs assisting ventilation
Is the skeleton of a bird lighter than that of a mammal?
NO, bird skeletons are no lighter than that of a mammal (by percent body mass), they do have les bone material by volume BUT the material they do have is denser and thicker , and birds also have a smaller ratio of skeletal mass to body area
What forces must be equal during flight such that a bird will not sink or slow down?
Thrust must be equal to drag so the bird does not slow down
Lift must be equal to weight or else the bird will sink
Describe the process of gliding in birds.
There must be an initial movement to establish forward trajectory, the wing then produces lift by a combo of downwash (if tilted) and Bernoulli’s principle (if upper surface is convex), BUT the wing can never generate enough lift to equal the weight of the bird therefore the animal inevitably sinks, but potential energy is converted to kinetic which creates thrust and allows the airspeed to be maintained while sinking
How does a glider maintain constant speed while sinking?
The ratio of lift (determined by wing shape and susceptibility to drag) dictates the angle of descent and the lower the angle of descent means that the bird can glide longer distances (albatross can glide for 20km)
What is soaring?
A glider can regain altitude by exploiting air movements such as updrafts caused by air rising in the heat of the morning sun (dynamic and static soarers)
What is flapping?
This entails producing thrust/lift with muscular activity and converting chemical energy into kinetic/potential energy
What are thrust and lift produced by?
Thrust is produced by movement of the outer wing, usually where the longest feathers occur
Lift is generated by the inner part of the wing acting as an airfoil (like in gliding but aided by speed resulting from extra thrust)
What are flapping movements?
These are complex and adjustable, cause flight feather of outer wing to rotate around their length, and are analogous to propellers
What is respiration like in birds ?
They have a highly efficient lung with 9 pneumatic sacs through which air is pumped in and out in one direction and provides the bird with enough oxygen to sustain flight and maintain high body temp
What is feeding and digestion like in birds?
Feed with the beak and have 2 specialized digestive chambers. The crop is not always present but when it is, it is used as an expanded area for food storage. The gizzard has muscular walls that may contain gizzard stones to assist in mechanical breakdown of food. These gizzard stones are usually found in seed eaters and insectivores/omnivores
What is courtship and reproduction like for birds?
Birds use both visual and vocal signaling for mating, males may have colorful plumage and have more elaborate calls than females (female choice more important). Female birds have ZW and males have ZZ and this system in not homologous to humans. Take care of nests and young usually extensively
