Birds:%20An%20Adventure%20Into%20Endothermy

1
Birds An Adventure Into Endothermy
2
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!

3
The Class Aves

• Approximately 10,000 species
• 29 orders
• Distributed over the Earth

4
Aves - Characteristics

• 1. Bipedal vertebrate
• 2. Keratinized beaks present (all birds)?
  toothless https//www.youtube.com/watch?vXzHQ5-
  lYvrk

Shape of bill adapted for different feeding
techniques.
5

• 3. Birds are endothermic!
• What does that mean?
• high body temperature
• Cost 20-30 times more energy

6

• Birds Lay eggs. Elaborate of all vertebrates
• Dedicated
• parental care
• Monogamous
• pair bonds
• (some for life)
• https//www.youtube.com/watch?vo42C6ajjqWg
• Amniotic egg with much yolk and hard calcareous
• shell.
• Incubation external.
• Sex determined by chromosomes
• Females are heterogametic.

7

• 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

8

• Birds are the only animals with
• feathers.
• Nearly all birds can fly
• flightless birds (ostriches and penguins) did
  evolve from flying ancestors.
• ( http//www.youtube.com/watch?vA5kzxOtvCjc
  315)
• Forelimbs modified into
• wings and hind legs
• (covered in scales)
• adapted for swimming,
• perching and walking.

9

• 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
• https//www.youtube.com/watch?vXjAcyTXRunY

10
FEATHERS !

• All birds are covered with feathers, collectively
  called plumage
• The main component of feathers is
  keratin, a flexible protein

http//www.youtube.com/watch?vY2yeNoDCcBg 150
11
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

12
Purpose

• signal their age
• sex
• social status
• Species
• identity to one another
• http//www.youtube.com/watch?vL54bxmZy_NE
• https//www.youtube.com/watch?vlMbDjNDD4cM
• Birds preen their feathers/oil glands

13
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.

14
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 feathersat least
  once a year usually after mating
• Tail feathers lost in pairs in order to keep
  balance
• Water birds lose plumage after mating - grounded

15
Flight Adaptations

• Skeletal system
• Muscles
• Respiratory System

16
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

17
Skeletal System

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

18
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

19
Ways to Fly

• Thermoclines/gliding
• Flapping flight
• No flight at all ratites - diverse group of
  large flightless groups most now extinct

20
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

21
Geese Flight The Art of Formation

• -save energy (up to 50)
• -cancels wing turbulence (big birds)

22
Feeding
Eat like a bird. Intense metabolism and
voracious eaters

• 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
23
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

24
HISTORY
25

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

26

• 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