Ornithology Exam 2 Lecture Study Guide

What are some unique features of a bird skeleton?

• talons 

• beak - used for tearing meat

• backwards looking legs 

• wing/arm-like structures 

How many tissues is the bird skeletal system composed of?

two tissues

Bones of the bird skeletal system

living cells in a matrix (osteoid) of fibrous protein

blood supply deposits and moves minerals 

calcium is resorbed and deposited in different bones as needed 

What is the overall purpose of the bones?

structure, directing the forces of muscles 

Cartilage/tendons/ligaments

connective tissue, cushioning, acts as pads between the joints

Ossification

becoming bone

Rigidity (Adaptation)

highly adapted for a life of flying

What is a unique feature of the bird ribcage?

they have an extra piece of bone that sticks backwards and overlaps the rib behind it

this creates an actual cage, adding additional rigidity to their bodies 

What are most of the adaptations to the bird skeleton tied to?

flight

Uncinate processes

finger-like protrusions in the rib cage

Pelvic region of a bird

strongly fused together, several vertebrate fused into one rigid structure 

adds rigidity to the skeletal system

“Hand” of a bird

fused together into a rigid structure

SUPER rigid, because of the upward force that lifts the bird into the air

length of humorous is shorter in birds 

Avian Skull

contains rings, bone inside the eye

aerodynamic-like shape made for flying 

pointed, long jaw

bones are very reduced, and the skull is open

sutures cannot be physically seen in bird skulls

Sclerotic Ring

ring around the eye that keeps the eyeball from deforming due to pressure changes 

Why do birds lack teeth?

since they have a gizzard located in their stomachs that chews and crushes food for them

this redistributes mass towards the center gravity around their wings

Pneumatized Bones

not all, but some bones are hollow

contain bone marrow for blood cell production

density of the bones is higher than the overall density of mammal bones

What runs through the hollow bones?

scruts, they create hollow chambers and air sacs where air can enter 

What issues may hollow bones cause for birds?

lungs or air sacs can be punctured due to breaking a bone, this can cause harm to the respiratory system

Furcula (wishbone)

clavicle

comes together and fuses at the end

air sac in the middle that gets pumped like a billow

energy is stored on the downstroke, and on the upstroke, it is released

Tail

cottle vertebrae are located here

sticks out, plate-shaped

Pygostyle

muscles that control a bird’s tail

Keel of the Sternum

most prominent bone in a chicken

massive blade, because it holds the muscles

a lot of muscle, because they generate flight, pulls a lot of Mass to the center of the wings 

smaller keel in birds that do not fly 

Why is a Casuary’s skull unique

has a feature called a “casque”

Casque

made of bone, useful for thermoregulation, heat can dissipate off the big bony plate, can conserve heat during the cold season

Skeletal Muscles

thousands of muscle fibers bound together with fascia

antagonistic function

voluntary

Smooth Muscle

“visceral",” spindle-shaped cells found in digestive system and small blood vessels

Cardiac Muscle

heart muscle

Contents of a bird muscular system

skeletal system

smooth muscle 

cardiac muscle 

Where is the muscular system located, and what is it mostly considered to be?

located near the pectorals/chest

mostly vascular 

Why do most ground nesting birds have unusually large flight muscles?

to enable fast escape, since they are on the ground and exposed, and so that they can take off quickly 

What would happen to a bird if the pressure to fly is removed?

pectoral muscles will shrink in size

flight muscles will also reduce

flight would also be quite weak 

Head and Neck of bird

semispinalis

muscles and jaw are very important for eating

contain complexus muscles

What do complexus muscles allow a bird to do?

allows them to rotate their heads all the way around and to be able to look upward

Pectoral girdle

sternum has a big blade for pectoral attachment 

Why do birds need to acquire food constantly?

birds exist on a very thin energy margin (always risking starving to death)

How do beaks vary between birds?

some birds have highly evolved beaks that pertain to the type of eating they do

Tomial Tooth

used for tearing flesh of prey

Why is it important to have habitat islands across the bird’s flight path?

habitat fragmentation

How can birds eat large food items with ease?

since they have a uniquely shaped esophagus

What is the bird esophagus connected to?

the trachea, and as long as they are not blocked, the bird can still breathe

Tongue

important part of digestion

very few taste receptors 

taste is not a deciding factor in what a bird eats, the texture of the item is more important to them

very few salivary glands 

What are different features found in berry-eating birds?

gross beaks tend to be more weaker, since berries are easier to grind up

they have highly reduced gizzards

Gut Fermentation

a bird has a massive crop, with multiple chambers