AVES Flashcards
Amniota
is the lineage with this reproductive pattern – nonavian reptiles, birds, mammals
Aves
- Phylum: Chordata
- Subphylum: Vertebrata
- Class: Aves
- 10,500 species
- 40 orders
Living birds (Neonithes) Are Divided Into Two Groups…
- Paleognathae (old jaw)
- Neognathae (new jaw)
Paleognathae (old jaw)
- are large, flightless, ostrichlike birds and kiwis
Neognathae (new jaw)
- are all other birds
Structures All Birds Have
- Feathers
- Forelimbs modified as wings, although not all can fly
- All birds have hindlimbs adapted for walking, swimming or perching
- All birds have keratinized beaks.
- All birds lay eggs
Mosaic Evolution
- Evolutionary Change in one or more body parts without simultaneous changes in other parts eg. evolution of birds from dinosaurs.
Contour Feathers
- Consist of hollow quill (calamus) emerging from skin follicle and a shaft (rachis) bearing numerous barbs
- Up to several hundred barbs are arranged to form a flat, webbed surface, the vane
- Each barb resembles a miniature feather Numerous parallel filaments (barbules) spread laterally
- Barbules from two neighboring barbs overlap and zip together with tiny hooks
- When separated, they are zipped back together by preening
Pneumatized bones:
pneumatized bones, light but strong
* Total weight of a bird’s feathers may outweigh skeleton
* Pigeon skull: 0.21% of body weight
* Rat skull: 1.25% of body weight
Pneumatized bones:
- Stiffened cross-struts and air spaces replace bone marrow
- Thin walls
- Remarkably light and strong.
Central Pattern Generator
A neural circuit (or single neuron) that generates a behaviourally significant pattern of motor output in space and time without requiring temporally patterned sensory input
How Is Flight Patterns Controlled?
i) Peripheral control
ii) Central Control
The Musculoskeletal System of Birds - Legs
- Main leg muscle mass is in thigh with connections by long tendons to feet and toes
- This places main muscle mass near a bird’s center of gravity
- Feet are nearly devoid of muscles
- Toe-locking mechanism prevents a perching bird from
falling off a branch while asleep
Pectoralis Muscle
- Depress the wing in flight and are attached to the sternum keel
Supracoracoideus Muscle
- Raises the wing, is also attached to the sternum keel * Lays under the pectoralis muscles
- Pulls the wing up from below by way of a “rope-and- pulley” type of arrangement
Four Basic Forms of Bird Wings: 1) Elliptical Wings
Birds that must maneuver in forested habitats have elliptical wings
Wing Slots (2 kinds)
Stalling (e.g. during sharp turns, low-speed flight, and frequent landing and takeoff) can be delayed or prevented by wing slots
- Alula
- Gaps between primary feathers
Alula
- group of small feathers on the thumb which provides a midwing slot
Gaps between primary feathers
- which create wing- tip slots
Four Basic Forms Of Bird Wings: 2) High-Speed Wings
- Birds that feed during flight or make long migrations have high speed wings.
- wings sweep back and taper to a slender tip, reduces turbulence.
Four Basic Forms of Bird Wings: 3) Active Soaring Wings
- Albatrosses, gannets and other oceanic soaring birds have wings with long, narrow wings
- The high-aspect ratio of long, narrow wings lack wing slots and allow high speed, high lift and dynamic soaring
Four Basic Forms of Bird Wings: 4) Passive Soaring Wings
- Vultures, hawks, eagles, owls and other birds of prey that carry heavy loads have wings with slotting, alulas and pronounced degree of curvature
