Birds -Notes by Yogini Soman

Animals are classified into two Kingdoms:

1. Protista

2. Animalia

Animalia have two major divisions:

a. Invertebrates:

b. Vertebrates: Animals having a vertebral column.

Vertebrates are further divided into six classes:

i. Protochordata

ii. Pisces

iii. Amphibia

iv. Reptilia

v. Aves

vi. Mammalia

Table 1.1 Difference between vertebrate classes

Ref. www.slideshare.net

Class Aves includes all birds and study of birds is termed as ‘Ornithology’.

What is Bird?

A Bird has been described as ‘Feathered Biped’ or vertebrate warm blooded animal

having two legs, wings and feathers on the body. This description is precise and cannot be

applied to any other animal.

Classification of birds are as follows:

Generally, there are about 9032 species of birds in the world. Most of the ornithologists

agree on dividing world birds into 28 orders, 170 families and 120 subfamilies. These families

contain from 1 or more than 300 species. Out of these, 21 orders, 11 subfamilies, 432 Genus and

1342 bird species are recorded from Indian subcontinent.

Fig 1.1 Classification of Birds

Ref. facinatingamazinganimals.wordpress.com

Fig 1.2 Example of bird classification

Ref. www.slideshare.net

Morphology of bird:

Morphology is a branch of biology dealing with the study of the form and structure of

organisms and their specific structural features.

Morphology includes:

1. External morphology or eidonomy:

Outward appearance means shape, structure, color, pattern, size.

2. Internal morphology or anatomy:

Form and structure of the internal parts like bones and organs.

Fig 1.3 Morphology of Bird

Ref. www.infovisual.info

Different kinds of Feathers:

Fig 1.4 Kinds of feathers

Ref. www.studyblue.com

Fig 1.5 Different kinds of feathers

Ref. www.poultryhub.org

Fig 1.6 Flight feathers of the wing

Ref. d--h.info

Fig 1.7 Flight Feathers of the wing their structure

Ref. www.britannica.com

Structure of feather:

Fig 1.8 Structure of feather

Ref. www.birdwatching-bliss.com

Anatomy of Birds:

Fig 1.9 Internal anatomy of bird

Ref. universe-review.ca

Respiratory System:

Fig 1.10 Respiratory System

Ref. people.eku.edu

Fig 1.11 Working of respiratory system

Ref. www.darwinismrefuted.com

Fig 1.12 Inhalation and Exhalation

Ref. science.kennesaw.edu

Circulatory System:

Fig 1.13 Circulatory System

Ref. www.slideshare.net

Fig 1.14 Circulatory System of bird

Ref. birds688.weebly.com

Nervous System of Bird:

The nervous system consists of nerve cells and nerve fibers forming gray matter and white

matter. Brain has nerve cells on its outer side or periphery while nerve fibers are in the core of it.

While in spinal cord the nerve fibers are outer side while the nerve cells are on the inner side.

The nervous system is divided into three regions:

1. Central Nervous Sysytem (CNS)

2. Peripheral Nervous System (PNS)

3. Symphathetic or Autonomous Nervous System

1. Central Nervous Sysytem:

It is well protected by the skull and vertebral column. It consists of brain which is lodged in

cranium and spinal cord. Brain as well as spinal cord are covered by a watery fluid i.e.

cerebrospinal fluid which protects them from shocks and injury.

Brain is further divided into three parts:

a. Fore brain: Consists of olfactory lobes, cerebrum and dicephalons.

b. Mid brain: Consists of optic lobes.

c. Hind brain: Consists of cerebellum and medulla oblongata.

2. Peripheral Nervous System:

It consists of paired nerves arising from brain and spinal cord. From the brain 12 pairs of cranial

nerves arise and enter in different parts of head and neck region. Some nerves are sensory, some

are motor while some are mixed type. From spinal cord paired spinal nerves arise. Generally

there is one pair per body segment in that region. All spinal nerves are of mixed type which carry

sensation and orders through them.

3. Symphathetic or Autonomous Nervous System:

It is represented by a pair of chains made up of sympathetic ganglia and sympathetic nerves

forming sympathetic cord which lies on either sides of vertebral column. It controls activities of

visceral organs (heart, lungs, liver, stomach, kidney etc.) with the help of spinal nerves.

Fig 1.15 Nervous System of bird

Ref. www.poultryhub.org

Fig 1.16 Brain of Pigeon

Ref. www.readorrefer.in

Fig 1.17 The organization of nervous system

Ref. people.eku.edu

Fig 1.18 Visceral Organs

Ref. www.rnpedia.com

Urinogenital System of Bird:

Fig 1.19 Excretory system of bird

Ref. slideplayer.com

Fig 1.20 Reproductive system of bird

Ref. slideplayer.com

Avian adaptations for flight are as follows:

1. Spindle shaped body.

2. Lack of teeth and mobile neck.

3. Beak with horny sheath.

4. Tail is short and used as steering organ or rudder and functions as a break and also helps

to maintain their balance.

5. Forelimbs modified as wings and presence of hind wings only.

6. Presence of feathers, scales and claws as exoskeleton. The non- conducting coat of

feathers prevents surface heat.

7. Endoskeleton fully ossified, spongy and light in weight but equally strong. There is

fusion of vertebrae. Bones are rod like, stout and pneumatic.

8. Absence of urinary bladder, hence excreta are in the form of semi-solid state.

9. Absence of right ovary in case of female birds.

10. Oviparous i.e. lay eggs.

11. Pectoral muscles of flight are well developed and in general all muscles are fully

developed, most energetic and powerful.

12. A very powerful heart with four chambers. Percentage of hemoglobin is much more.

Circulatory system is very efficient and serves as power station.

13. Body temperature is internally regulated and is generally between 38°C and 44°C. Hence,

they are called as warm blooded or homoeothermic animals.

14. Air does not remain in lungs so respiration is complete.

15. Presence of internal air sacs in the body, not only help to increase the buoyancy but also

serve as efficient aerial mode of life, balancing and steering device to the bird.

16. Extra energy and sustained power is obtained through rapid and complete combustion of

the fuel.

17. Sight and hearing are highly developed whereas taste and sense of smell are very poorly

developed.

Bird Beak:

Fig 1.21 Beak shapes of different birds

Ref. www.infovisual.info

Fig 1.22 Different types of beak

Ref. www.pinterest.com

Fig 1.23 Types of beaks depending upon the type of food

Ref. www.filamentgames.com

Colour of feathers:

Importance:

1. Camouflage for concealment

2. Recognition as an individual

3. To differentiate between male and female

4. Sexual display and stimulation of reproductive development

Different parts of legs:

Fig 1.24 Parts of leg

Ref. en.wikipedia.org

Types of bird foot:

Table 1.2 Type of bird foot and adaptation and life style

Ref. www.sciencebuddies.org

Fig 1.25 Evolution of foot

Ref. blog.hmns.org

Types of nests:

Fig 1.26 Various types of bird nests

Ref. www.lookanimals.com

Fig 1.27 Various types of bird nests

Ref. birdnest.my

Eggs:

Fig 1.28 Eggs of various birds:

Ref. www.angelfire.com

Why flight evolve?

1. To help escape from predators

2. To help catch flying or speedy pray

3. Leaping or glinding

4. To free hind legs for use as weapons

5.

Aerodynamics of Avian Flight:

Four basic forces come into play when a bird wants to fly. These are opposing set of forces.

1. Lift: Force that enables a bird to go in the air.

2. Gravity: Force that pulls the bird down towards the earth.

3. Thrust: Force that propels the bird forward in flight.

4. Drag: Force that pulls the bird backwards in flight.

To fly, the lift should exceed gravity and thrust should exceed drag.

Daniel Bernoulli in 1738 described the forces acting on a body moving through fluid in a

scientific paper called ‘Hydrodynamica’. The principles are also valid for forces in flight.

Fig 1.29 Forces important for flight

Ref. vireo.ansp.org

Fig 1.30 Interactions among various components in avian flight

Ref. people.eku.edu

Fig 1.31 Downstroke and Upstroke

Ref. kpubs.org

Types of flight:

1. Flapping

2. Gliding

3. Soaring

4. Hovering

5. Dive

6. Pitch-up

7. Maneuvering

8. Fly under water

9. Flying in formation

Fig 1.32 Different types of flight

Ref. people.eku.edu

Types of Wings:

Fig 1.33 Major types of wings

Ref. www.birds.cornell.edu

Flightless Birds:

During the process of evolution, some birds now called as Paleognathae (Kiwi, Ostrich, Emu),

did evolve with some adaptations to fly, but did not actually fly and remained flightless.

Others did evolve to fly and did actually fly in the early years; these birds are now put in the

group called Neognathae (Penguins, Parrots, Owls and Cormorants etc.).

Why some birds are flightless?????

1. Absence of predators

2. Less competition

3. Adapted to fit in different ecological functions

4. Defense against predators

Fig 1.34 Examples of flightless birds

Ref. www.exploringnature.org

Migration of Birds:

Fig 1.35 Reasons of bird migration

Ref. www.slideshare.net

Patterns of Bird Migration:

1. Horizontal Migration:

a. North- South Migration:

In harsh cold climate of northern winter when food is depleting, the birds migrate

southwards to warmer climates.

e.g. Swallows of Scandinavia migrate while those from Italy are resident.

b. Partial Migration:

Birds living in latitude belts where temperature do not drop too much, but produce

moderate food scarcity, migrate partially. Some birds benefit by staying others have

migrated because the remaining scarce food is just enough for them to overcome

winter. Usually the young birds migrate and the adults stay.

e.g. Evening Grosbeaks.

c. South to North Migration:

e.g. Vermillion Flycatchers of South America. They breed in Pampas grasslands of

Uruguay in the southern summer and migrate to savannas of Brazil in winter.

d. Inter-polar Migration:

Arctic terns migrate over the longest distance, since they chase the summer in both

hemispheres by travelling from one pole to the other.

e. Circumpolar Migration:

Most species of Albatross migrate around the South pole and they usually do not

cross the 40 degrees latitude and keep between the roaring forties and furious fifties

but may move further south.

f. East to West Migartion:

e.g. Redwings. They breed in Russia and adjacent northern Europe and in winter they

migrate to the West and Southern Europe.

g. Migartion in any Direction:

Several water birds migrate in any direction that leads them to warmer conditions on

water bodies, approach either inland water bodies in lower altitudes with abundant

food or coastal areas where temperature is relatively warmer.

e.g. Shore birds migrate along the coasts.

h. Oceanic Migration:

Ocean birds from southern hemisphere migrate to procure more food where it is

available but their movements are dictated not only by the ocean currents but also by

the favourable winds.

e.g. Shearwaters, Petrels.

i. Leapfrog Migration:

When for food compulsions, resident birds develop migrant members, they have to

jump or leapfrog adjacent resident bird occupied areas to find less populated feeding

areas that can sustain their demands.

e.g. Fox Sparrows of North-west America and Canada.

2. Vertical Migration:

a. Altitudinal Migration:

In the Himalayas, Andes and the Alps many pheasants, grouse and chaffinches are

altitudinal migrants.

b. Reverse Migrantion:

Due to adverse weather, depletion of energy, migrating birds reverse their direction of

flight.

Birds orient and navigate themselves during migration with the help of

several compasses such as:

1. Magnetic Compass

2. Sun Compass

3. Star Compass

4. Road Map Compass

5. Olfactory Compass

6. Sound Compass

7. Ancillary Compass

Different Flyways:

Fig 1.36 East Asian- Australian Flyways

Ref. www.wetlands.org

Fig 1.37 Asian Migratory Bird Flyways

Ref. en.wikipedia.org

Fig 1.38 Different bird flyways

Ref. wgbis.ces.iisc.ernet.in

Fig 1.39 North and South flyways

Ref. www.pinterest.com

Fig 1.40 Migration of different birds

Ref. northern.org

Fig 1.41 Migration of different birds

Ref. en.wikipedia.org

Fig 1.42 Migration map of Indian Subcontinent

Ref. Salim Ali, The Book of Indian Birds, BNHS India, 13th

Edition, 2002

Habitats of Birds:

1. Atlantic & Gulf Shores:

a. Bays & Estuaries

b. Beaches & Dunes

c. Gulf/Rocky Shores & Open Ocean

2. Eastern Forests:

a. Boreal/Coniferous Forests

b. Deciduous/Mixed Forests

c. Pine Barrens & Pinelands

3. Grasslands:

a. Eastern Grasslands

b. Farmlands

c. Prairies

4. Suburb/Urban Areas

5. Wetlands:

a. Bogs

b. Lakes & Ponds

c. Marshes & Swamps

d. Rivers & Streams

Birds food and feeding:

Classification of birds according to diet types:

1. Piscivorus: Terns, Gulls.

2. Carnivorus: Owls, Eagles

3. Carrion Eaters: Vultures, Eagles, White Ibis

4. Insectivorous: Bee- eaters, Swallows

5. Molluscivorous: Shorebirds, Asian Open Bill Stork

6. Avivorous: Perigreen Falcon, Shikra

7. Ophiphagous: Owls, Short toed snake eagle

8. Kleptoparasitic: Raptors, Gulls, Terns

9. Aquatic Filter feeders: Greater and lesser flamingo, Ducks

10. Granivorous: Dove, Sparrows

11. Nectivorous: Sunbirds, Oriental white eye

12. Frugivorous: Hornbills, Parrots

13. Omnivorous: Ducks, Bulbuls

Types of foraging:

Simple act of gathering food, either for immediate consumption or future storage.

1. Scratching: sparrows, grouse

2. Gleaning: Nuthatches, chickadees and tits glean in trees, warblers often glean from

leaves and thrushes often glean from the ground.

3. Hawking: Warblers, Flycatchers

4. Sallying: Flycatchers, Rollers

5. Scanning: Raptors

6. Probing: Sandpipers, Shorebirds

7. Lunging: Plovers, Herons

Plant- bird interactions:

Two types of plant and bird interactions:

1. Direct Interaction:

a. Pollination

b. Seed dispersal

2. Indirect Interaction:

a. As a pest controller

b. Nesting and roosting sites

c. Escape from predation

Breeding Behavior of Birds:

1. Monogamous: One partner

2. Polyandrous: One female mate with many males

3. Polygynous: One male mate with many females

4. Promiscous: No partnership with anyone. Combination of polyandrous and polygnyous

5. Lek or Communal:

6. Communal Courtship: Flamingo

Bird Communication:

Birds produce a variety sounds to communicate with flock members, mates (or potential mates),

neighbors, & family members. These sounds vary from short, simple call notes.

Classification of vocalizations:

1. Songs:

a. Primarily under the influence of sex hormones

b. Generally important in reproduction (e.g., defending territories & attracting

mates)

2. Calls:

a. Generally concerned with coordination of the behavior of a pair, family group, or

flock (e.g., several vocalizations of Carolina Chickadees)

b. Not primarily sexual, but important in 'maintenance' activities, such as foraging,

flocking, & responding to threats of predation

c. Usually are acoustically simple (e.g., contact notes of Northern Cardinals)

d. May serve a variety of functions: location/contact/individual recognition

Statistical analysis:

Used to quantitate the event.

Central tendencies used are as follows:

1. Mean

2. Mode

3. Median

For measuring diversity different indices are used:

1. Margalef’s Index

2. Simpson’s Index

3. Shannon’s Index

4. Evenness in diversity

5. Jaccard Index

6. Bray- Curtis Index