BIRDS - IIOther Characteristics of Birds:

B) Skeleton & Muscle

1) Skeleton combines lightness and strength

2) Bones are thin and hollow.

3) Sternum – breastbone is the attachment for flight muscles

Rock dove

4) Furcula – (wishbone) fused collarbones

5) Flight involves complex muscle movement (in some birds the flight muscles account for 50% of the bird’s weight.)

Wing muscles

C) Metabolism – Birds demonstrate endothermy (warm-blooded) which means they generate heat internally.

D) Digestions: No teeth, so they swallow food without chewing. Food passes into an enlarged portion of the esophagus called the crop, which stores and moistens food.

It then passes to the first part of the stomach called the proventriculus, where enzymes start to breakdown food.

• It then passes to the gizzard which is the muscular portion of the stomach. It contains small stones, which the bird has swallowed, to help grind food.

• It then passes to the small intestine where nutrients are absorbed.

• E) Excretion of wastes: Liquid wastes are not stored. Kidneys filter nitrogenous waste called uric acid from the blood. It travels to the cloaca where it mixes with undigested matter from the intestines and is then eliminated.

F) Respiration: -highly efficient

1) Birds use lungs and air sacs (which also decrease density)

2) Air sacs extend into long bones

G) Circulatory System

1) pulmonary & systemic circulation

2) 4-chambered heart ostrich heart beat 70 beats a minute hummingbird heart beats 600 times a minute chickadee heart beats 1000 times a minute

3) Bird red blood cells have nuclei

bird heart model

H) Nervous System & Sense Organs

1) large brains for their size a) highly developed areas to control flight-

related functions such as the cerebellum, which controls movement

2) Very good vision

a) necessary for taking off landing and spotting prey.

b) good color vision.

All About Foveae• The fovea is a teeny central patch about a millimeter across in the

center of the retina of your eye. In the fovea, rods and cones are packed way more densely together than over the rest of the retina. (This close-packing is achieved in part by making the rods & cones smaller.)

• The increased density of receptors allows for the formation of a sharper image. It’s always the focus of our vision, which is the reason why things are always clearest when we center our field of vision on them.

Of all the mammals, only primates have Foveae. And specifically only Simian primates, which means just monkeys and apes. So just like we have better color vision than pretty much all other mammals (“we” in this case being us and our ape/monkey cousins) we also have the only foveal vision among the mammals.

Second, just as birds blow us away in color vision, they similarly trounce us in foveal vision. Birds (and many reptiles) do have foveae, and the foveae of birds are packed way more densely with cones and rods than are human foveae, Our foveae have about 200,000 receptors per square millimeter. A hawk’s foveae have around 1,500,000 receptors per square millimeter.

Red-Tail Hawk

But lots of birds’ eyes have a second fovea, positioned to provide foveal vision outside of the forward-facing binocular field. This is monocular foveal vision and it greatly helps birds such as hawks and eagles identify motion and prey in their peripheral field of vision as well as judge speed and distance- both their own and that of things they’re watching/chasing.

c) birds with eyes on the side of their head have a wide field of view, while those with eyes near the front have good binocular vision to perceive depth of field.

3) Hearing – important to songbirds and owls (use sound to locate prey)

4) Sense of smell is well-developed.

• Bird noses are structurally quite similar to the general vertebrate plan, and many ornithologists have noted that different bird groups emit surprisingly strong scents. In other vertebrates, odors function in numerous social situations that involve an exchange of information between members of the same species. This can be as straightforward as a dog marking its territory, or perhaps more complex, such as two animals displaying while they simultaneously assess the odor of a prospective mate.

Assistant Professor of Biology Julie Hagelin,

I) Reproductive System:• Testes in males produces sperm that travels by the vas

deferens to cloaca • Females have single ovary that makes eggs • Eggs are fertilized in the oviducts • Shell added by shell gland & then egg moves into  • In mating, male presses cloaca to female to transfer

sperm (internal fertilization)

Amniote bird egg

chalaza turns embryo toward mother’s warmth

J) Care of Young:

1) Precocial birds – are active as soon as they hatch (ducks, quails,etc.)

2) Altricial birds – blind and naked after hatching and are helpless they depend on parents for several weeks.

• K) Migration: seasonal movement of some bird species to exploit spring and summer resources in temperate regions.

Geese Flocking to Mexico

L) Bird Vocalizations

• A songbird is a bird belonging to the suborder Passeri of the perching birds (order Passeriformes – about 4000 species)

• Uses a vocal organ to produce a diverse and elaborate bird song.

• There is evidence to suggest that songbirds evolved about 50 million years

• This 'bird song' is essentially territorial in that it communicates the identity and whereabouts of an individual to other birds and also signals sexual intentions. It is not to be confused with bird calls, which are used for alarms and contact, and are especially important in birds that feed or migrate in flocks. While almost all living birds give calls of some sort, well-developed songs are only given by a few lineages outside the songbirds.

Birds Using Tools - The Galapagos woodpecker finch grasps a cactus spine in its beak and pries grubs out of a branch.  The finch then drops the cactus spine and holds it under its foot while eating the grub.  The cactus spine is carried from branch to branch for reuse.

THE SHRIKE: A predatory songbird, the Northern Shrike breeds in

taiga and tundra and winters in southern Canada and the northern United States. It feeds on small birds, mammals, and insects, sometimes impaling them on spines or barbed wire fences.

It can kill its prey by impaling them on thorns or wedging them between branches. It cannot hold onto prey with its feet, so it is easier to use a thorn or similar structure to hold prey as it eats.

Impaled insects

An impaledchameleon.An impaled mouse

A bird wedged at the neck.