Birds: An Adventure Into Endothermy

Birds Flying machine  all aspects of its anatomy and physiology are integrated for: 1. Maintenance 2. Growth 3. Reproduction BIRDS LIVE AN ENERGETICALLY COSTLY LIFE!

The Class Aves Approximately 10,000 species 29 orders Distributed over the Earth

Aves - Characteristics 1. Bipedal vertebrate 2. Keratinized beaks present (all birds)  toothless Shape of bill adapted for different feeding techniques.

3. Birds are endothermic! What does that mean? –high body temperature –Cost: times more energy

4.Birds Lay eggs. Elaborate of all vertebrates Dedicated parental care Monogamous pair bonds (some for life) Amniotic egg with much yolk and hard calcareous shell. Incubation external. Sex determined by chromosomes Females are heterogametic.

4.Birds Lay eggs. Precocial - young active at hatching Altrical – young helpless and naked ALTRUISM When parents get help in feeding and guarding young by other adults who have not bred that year. Seems contrary to “survival of fittest” But “altruistic” helpers must be closely related to parents – so still helping genes get passed one

5.Birds are the only animals with feathers. Nearly all birds can fly flightless birds (ostriches and penguins) did evolve from flying ancestors. ( 3:15) 6.Forelimbs modified into wings and hind legs (covered in scales) adapted for swimming, perching and walking.

7. Larger developed brains Large cerebellum and optic lobes Able to learn-vocalizations, social behavior Syrinx-sound producing organ Complex navigation (magnetic fields) Color vision

FEATHERS ! All birds are covered with feathers, collectively called plumage The main component of feathers is keratin, a flexible protein 1:50

Purpose flight strong yet lightweight surface area needed for aerodynamics insulation trapping pockets of air to help birds conserve their body heat Lab: Dissection of Feathers

Purpose … signal their age sex social status Species identity to one another Zy_NE DD4cM Birds preen their feathers/oil glands

Bristles specialized feathers perform a tactile function. found around the mouth or eyelids. Insect eater - act as funnels, helping the birds to scoop insects out of the air. Owls - act as sensors of nearby objects. Woodpeckers - act as a filter for the dust produced as they drill holes in trees.

Molting Feathers, like mammalian hair, are dead. Most adult birds molt gradually to avoid bare spots. Penguins molt all at once. Lose and replace their feathers—at least once a year usually after mating –Tail feathers lost in pairs in order to keep balance –Water birds lose plumage after mating - grounded

Flight Adaptations Skeletal system Muscles Respiratory System

Bird Flight - Skeleton Lightweight sturdy skeleton. Vertebrae are fused except in cervical and tail. Contain air cavities – make them lighter. Sternum bears a large, thin keel where flight muscles are attached. (not in flightless birds) Elastic Furcula (fused clavicles) – stores energy as it flexes when wings beat. Key forces- weight, lift, drag and thrust

Skeletal System Hallux present (rare among vertebrates) - the first toe / points backwards - perching / grasping

Bird Flight - Muscles 2 major flight muscles –Pectoralis  depress wing in flight – Supracoracoideus  raises wing in flight –Both are attached to keel Goal: overcome force of gravity Key forces – weight –lift –drag –thrust

Ways to Fly Thermoclines/gliding Flapping flight No flight at all: ratites - diverse group of large flightless groups – most now extinct

Respiration System Nostrils, tracheal system, lungs and air sacs Key: no residual air left in lungs, more efficient Unidirectional air flow Two complete cycles required to complete a breathe HIGHLY efficient

Geese Flight: The Art of Formation -save energy (up to 50%) -cancels wing turbulence (big birds)

Feeding Food swallowed whole Prey upon: –Insects – there is bird to eat every kind –Worms, Mollusks, Crustaceous Fish, Frogs, Reptiles and Mammals, as well as other Birds –Nectar Euryphagons – wide eating Stenophagons – narrow eating PROs and CONs “Eat like a bird.” Intense metabolism and voracious eaters

Digestive System Highlights Birds process food rapidly. Crop – enlargement of the esophagus –stores food soften Two chambered stomach –A. proventriculus – secretes gastric juices –B. gizzard – lined with keratinized plates for grinding food. Birds also swallow objects to help in grinding

HISTORY HISTORY

Archaeopteryx 147 million year old relative of modern bird Fossil discovered in1861 in Germany More reptilian-like except for the imprint of feathers

Birds and Reptiles have… –Skulls are similar –Single middle ear bone – stapes –Lower jaw composed of 5 or 6 bones –Excrete their nitrogenous wastes of uric acid –Lay similar yolked-eggs Feathers evolved from reptilian scales, bird feet / still scales