Beautiful Birds!

Classification Kingdom Animalia Phylum Chordata Subphylum Vertebrata Class Aves 27 Orders

Evolution Evolved from dinosaurs (theropods). Best known link between dinosaurs & birds is the fossil Archaeopteryx - had traits of both: large skull w/ teeth, non-hollow bones, forelimbs w/ claws, scaly legs, long tail (reptile/dinosaur), feathers & furcula (birds).

Archaeopteryx

Evolutionary Success of Birds Flight - escape, exploitation of new niches, dispersal, long-distance migration. Endothermy - “warm bloodedness”. Parental care of offspring.

Characteristics of Birds Body mostly covered in feathers. Most species use forelimbs for flight. Bipedal, w/ clawed toes. Bones thin & hollow, skeleton rigid in places. Keeled sternum. Furcula - fused clavicles, a.k.a. “wishbone” Toothless, horny beak composed of keratin. Endothermic - body temp. generated & regulated internally. 4-chambered heart, keeping oxygenated blood separate helps with energy needs. Amniote eggs in hard, calcium-based shell. Eggs incubated by parents in nest.

Feathers Modified scales provide lift, control, aerodynamic shape, insulation. Shaft (quill) separates feather into 2 vanes. Each vane composed of many barbs. Barbs have many barbules. Hooks attach adjacent barbules to each other so feather keeps its shape & strength.

Types of Feathers Down feathers - fluffy, no vanes, no hooks on long, flexible barbs. Contour feathers - provide streamlines shape, coloration, & extra insulation. Flight feathers - specialized contour feathers on wings & tail for lift and control.

Feather Maintenance Preening – major behavioral activity using beak to straighten feathers & rub w/ oil from preen gland for conditioning, waterproofing. Molt – major molt (late summer) replaces worn flight feathers prior to migration/winter. Some species have spring molt prior to courtship.

Skeletal/ Muscular Systems Bones thin & hollow, strengthen by bony struts inside. Fewer bones than other vertebrates – many fused for rigidity – provides stability in flight. Keeled sternum – large surface area for attachment of large flight muscles. Furcula – “Wishbone” – fused clavicles, supports shoulder joints. Pygostyle – supports tail feathers for lift and steering. Lightweight beak made of keratin. Skeletal/ Muscular Systems

Digestive System Quick & efficient Crop – temporary food storage, moistens food. Proventriculus (stomach), chemical digestion begins. Gizzard – muscular, grinds food, increases surface area of food. Uses gravel bird has ingested. Duodenum – receives bile from liver & enzymes from pancreas. Intestine – nutrient absorption. Cloaca – undigested food exits. Digestive System

Excretory System Efficient, lightweight Kidneys filter uric acid from blood. Concentrated uric acid moves via ureters to cloaca exits with undigested food. No bladder (saves weight), so birds eliminate often. Excretory System

Respiratory System Lungs + 9 air sacs, reduce bird’s density. Inhales, some air goes to lungs, 75% to posterior air sacs Exhales, air from posterior air sacs moves into lung. Bird gets fresh O2 both inhaling and exhaling.

Circulatory System 4-chambered heart, 2 separate ventricles keep oxygenated & deoxygenated blood completely separate. Heart larger than mammals relative to body size. Rapid heartbeat (smaller birds 1000 bpm).

Bird Identification Field marks by sight: Overall size Beak size & shape Foot characteristics Leg length Overall color, isolated patches Stripes/streaks/bars on various areas (head, breast, wings, tail)

Bird Identification Behavior Posture Movement – walking, perching, and/or flight Nest site/type Habitat Geographic area Feeding habits Songs and calls Bird Identification

Reproductive System Weight-saving – eggs laid as they are formed, not held in body. Internal fertilization (advantages?) Shell gland within oviduct surrounds egg with calcium carbonate shell. Shares opening (cloaca) with digestive and excretory systems.

The Amniote Egg Adaptation to life on land Miniature self-contained “aquatic environment” prevents water loss. Amnion – surrounds embryo amniotic fluid (salts & electrolytes). Yolk sac – encloses yolk, food source rich in proteins & lipids (fats). Allantois – stores nitrogenous waste products until egg hatches. Chorion – lines outer shell, encloses embyro & other membranes Chorion allows for gas exchange with environment. Albumen – Water & protein – suspends & protects the embryo.

Beaks

Feet Usually covered with scales. Specialized to fit lifestyle of bird - often matched with a particular type of beak. Grasping - stout toes w/ sharp talons. Wading - long, slender toes distribute weight over lg. area. Swimming - broad, flattened toes or webbing in between. Climbing - 2 toes forward, 2 back for grasping vertical surface. Perching - small, delicate toes for grasping twigs. Feet

Fish-eating beak: long, slim, strong, and pointed to reach into the water and to grasp slippery creatures Insect-catching beak: small beak that can open wide to grab insects in flight Seed-eating beak: arched into the shape of a cone; stout and sharp to crack seeds Insect- and Fruit-eating beak: narrow and pointed to grab insects or reach for fruits, and slightly arched to crack seeds; larger than an insect-catching beak but shorter than a fish- eating beak; sleeker and longer than a seed-eating beak Straining beak: wide and shallow; comb-like strainers on edges filter out bits of food in the water Chisel beak: sturdy and sharply pointed to chisel into wood; accompanied by an extremely long, barb-tipped tongue to pull insects and insect eggs out of tunnels in bark or wood Preying beak: stout, sharp, and sharply hooked to tear into the flesh of animals Probing beak: thin and long to reach insects and other small animals buried in mud or sand