1. VERTEBRATE ZOOLOGY (VZ Lecture24 – Spring 2012 Althoff - reference PJH Chapters 16-17)
Birds – Part II
Bill Horn

2. Body Form and Skeleton
Feathers: molded for aerodynamic forces; light, strong…very resilient for their weight
Skeleton: a) skull is remarkably light b) wing bones air filled c) leg bones heavier than same-sized mammal *overall: more mass is concentrated in ____________ than comparable sized mammals

3. Body organ “reductions”
Birds ______ urinary bladders
Most birds have only one ovary (or only one _______________ ovary)
_________ of both sexes are usually small (with hypertrophy or regression depending on time of year)

4. Muscle & Cardiovascular Output
Pectoral muscles (major wing muscles-downstroke) may account for ______ of total body mass of strong fliers power output per unit of mass for dove estimated to be 10-20x that of most mammalia muscles
_______ heart and high rates of blood flow coupled with complex lungs that a) maximize gas exchange b) dissipate heat produced by high levels of muscular activity during flight

5. FAVEOLAR
LUNG

6. Streamlining
Birds _____ vertebrates that move fast enough for wind resistance and streamlining to be important
“Fast birds” songbirds: up to 50 km per hour ducks & geese: up to km per hour peregrine falcon: 200 km per hour in dive
Structural characteristics like fast-flying aircraft: ______________ make smooth joints between wings and body, and head and body ___________ close to body in flight

7. Not-so-streamlined
Some birds are slow fliers….slow to launch into flight, slow in-flight
“Slow birds” spoonbills flamingos herons cranes
Structural characteristics opposite of fast-flying aircraft: long-legged with legs that trail behind and/or not tucked up under the body long-necks extended

8. Air-filled bones…fused and thinner bones
Also referred to as ____________ bones
Not present in all birds
Better developed in larger birds than smaller birds
Diving birds (penguins, grebes, and loons) have little pneumaticity in their bones
Skeletons of most birds exhibit some pneumaticity in pectoral girdle and humerous
Pelvic girdle: elongated with ischium and ilium broader and much thinner than ancestral reptile line….and combined with the synsacrum—a fusion of vertebrate…. pygostyle—fused caudal vertebrate

9. Fusion of vertebrae means more rigidity
Overall, reduction in number of vertebrae and fusion of vertebrae…and relatively immobile thoraic vertebrae…in combination with elongated, “roof-like” pelvis produce a nearly RIGID vertebral column.
The rigid “trunk” is balanced on the legs
Femur projects to the anterior…combined with articulation of with the tibiotarsus and fibula results in this being the bird’s center of gravity

10. center of
gravity

11. Other “skeleton” features of note….
Wings positioned above the center of gravity
Sternum greatly enlarged (most with keels…as noted) for greater amount of surface area
Scapula extends posteriorly above ribs and is supported by coracoid which is fused ventrally to the sternum
Clavicles project to anterior—usually fused to form the furcula (wishbone)… provides additional bracing
Hind foot typically greatly elongated with ankle joing within the tarsals
Tarsometatarsusmetatarsals of some toes fused with the distal tarsals
Tibiotarsustibia fused with proximal tarsal bones

12. Muscles – Mass distribution differences
Hummingbirds & swallows mostly flight
Predatory birds flight but use legs to capture prey
Swimming birds
“Terrestrial” birds --run instead of fly to flee
flight muscles ________ of
total body mass, legs _____
flight muscles ~_____ of
total body mass, leg _____
limb & flight muscles about
equal percentage, overall
_______ of total body mass
limb muscle mass ___ than
flight muscle mass

13. Muscles
Two basic processes “fuel” muscle contract: a) ____________ metabolic pathways --achieve “quick” response does not requires O more fast-twitch muscle fibers, relative
to slow-twitch muscle fibers b) ___________ metabolic pathways --achieve “sustained” response --requires O more slow-twitch muscle fibers, relative to fast-twitch muscle fibers --slow-twitch muscle fibers contain lots of _____________

14. Fast vs. Slow Twitch Muscle Fibers
Category Slow-Twitch Fast-Twitch
_____________ more fewer
_____________ more less
Myoglobin more less
Color appearance red-brown white
____________ build-up lower higher
Fatigue slower quicker

15. Muscles & Birds Other “flier” vs. “runner” differences
Composition of leg muscles indicates regular, sustainable activity
Composition of breast muscles (major muscle groups responsible for up- and downstroke of wings) indicative to long vs. short flight capabilities
Fliers—(think songbirds, waterfowl, etc.) a) legs: large amounts of myoglobin b) breast: large amounts of myoglobin
Runners—(think quail, pheasant, wild turkey) a) legs: large amounts of myoglobin b) breast: essentially lack myoglobin

16. Major Flight Muscles
↓ __________________ – origin on keel of sternum (lateral side) and inserts at humerus on ventral side
contracts for ______________ relaxes during upstroke
↑ _________________ – origin on keel of sternum (lateral side), passes through foramen triosseum, inserts (tendon) on dorsal head of humerus. Foramen trosseum formed by articulation of the furcula, coracoid, and scapula relaxes during downstroke contracts for ______________

17. pectoralis

18. supracoracoideus

19. Foramen triosseum __________________
Left humerus
Foramen
triosseum
right humerus
__________________

20. Major Feather Types on the Wing
Primaries (remiges = wing feathers)
Secondaries (remiges = wing feathers)
Major coverts – leading edge of wing
Alula—forms wing slot on leading edge (at carpal bones

21. Major Feather Types on the Wing
Fig p444, PJH