Waves

The wave is a form of disturbance which transmits energy from one place to another without the actual flow of matter as a whole. Waves are of three types: Mechanical waves, Electro Magnetic waves, matter waves. Water waves or sound waves are called mechanical or elastic waves as they require a material medium for their propagation. A material possesses both elasticity as well as inertial. Light waves don’t require any material medium for their propagation. Light waves are electromagnetic or non-mechanical waves which can propagate through vacuum. Matter waves are associated with moving electrons, protons, neutrons and other fundamental particles and even atoms and molecules. The matter is constituted and other fundamental particles and even atoms and molecules. The matter is constituted by electrons, protons, and neutrons and other fundamental particles. The waves associated with matter particles are called matter waves. Matter waves arise in quantum mechanical description of nature. Wave motion in a form of disturbance which is due to the repeated periodic vibrations of the particles of the medium about their means positions. The motion is handed over form one medium particle to another without any net transport of the medium during wave motion. Mechanical waves are of two types i.e. transverse waves and longitudinal waves. A wave is said to be progressive or travelling waves if it travels from one point of the medium to another. The waves on the surface of water are of two types: capillary waves and gravity waves. The restoring force that produces gravity waves is the pull of gravity which tends to keep the water surface as its lowest level. The oscillation of the particles in gravity waves is not confined to the surface only, but extends with diminishing amplitude to the very bottom. The particle motion in water waves involves a complicated motion, they are not only moving up and down but also back and forth. The waves in an ocean are a combination of both longitudinal and transverse waves. Transverse and longitudinal waves travel with different speeds in the same medium. “k” is called the propagation constant or angular wave number. S.I unit of “k” is radian (rad) per meter.
Sound waves are mechanical waves which can’t propagate in vacuum. The speed of sound does not depend on the frequency or wave length. Sound waves can’t travel in saw dust or dry sand because the medium is not continuous. The damping of sound in wood is much larger as compared to that in metals. Higher the frequency of sound greater is the pitch of sound. The voice of ladies and children is of higher pitch than that of men. The sound is reflected and refracted according to the same laws as light does. The wave length for ultrasonic is very small, therefore they are not diffracted by ordinary objects or holes etc. The speed of mechanical waves is determined by the properties of the medium i.e. elasticity and inertia and not by the nature, intensity, amplitude or shape of the wave. Velocity of sound is largest in hydrogen among gasses. Monosyllabic sound is produced in about 0.2 s. The vibration of the prongs of a tuning fork is the transverse and that of the stem are longitudinal. The point where stem of a tuning fork is connected to the prongs is antinodes. The end of the prongs is also antinodes. There is node between them which is nearer to the stem than the ends of the prongs. The speed of sound in the air is not affected by the changes in pressure. For every 1⁰C rise in temperature, the speed of sound increases by 0.61 meter per sec. Due to change in temperature, the wavelength of sound waves is affected. Beats are not audible if beat frequency is more than 10Hz. If the prong of a tuning fork is loaded near the stem its frequency increases and when it is filled near the stem, the frequency decreases. The number of beats produced per second is equal to the difference in the frequencies of the superposing notes. In the progressive waves, the crest and troughs or compressions and rarefactions move with the speed of the wave. When there is no relative motion between the source and listener, the Doppler’s effects is not observed. When a source of sound moves, it cause change in wavelength of the sound received by the listener. If source and listener move in a mutually perpendicular direction no Doppler’s effect is observed.

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By teenstudents Posted in Biology

PLANT GROWTH AND DEVELOPMENT

PLANT GROWTH AND DEVELOPMENT

Growth is one of the most conspicuous events in any living organism. It is an

irreversible increase expressed in parameters such as size, area, length, height,
volume, cell number etc. It conspicuously involves increased protoplasmic material.
In plants, meristems are the sites of growth. Root and shoot apical meristems
sometimes alongwith intercalary meristem, contribute to the elongation growth of
plant axes. Growth is indeterminate in higher plants. Following cell division in root
and shoot apical meristem cells, the growth could be arithmetic or geometrical.
Growth may not be and generally is not sustained at a high rate throughout the
life of cell/tissue/organ/organism. One can define three principle phases of growth
– the lag, the log and the senescent phase. When a cell loses the capacity to divide,
it leads to differentiation. Differentiation results in development of structures that
is commensurate with the function the cells finally has to perform. General principles
for differentiation for cell, tissues and organs are similar. A differentiated cell may

dedifferentiate and then redifferentiate. Since differentiation in plants is open, the
development could also be flexible, i.e., the development is the sum of growth and
differentiation. Plant exhibit plasticity in development.
Plant growth and development are under the control of both intrinsic and
extrinsic factors. Intercellular intrinsic factors are the chemical substances, called
(PGR). There are diverse groups of PGRs in plants,
principally belonging to five groups: auxins, gibberellins, cytokinins, abscisic acid
and ethylene. These PGRs are synthesised in various parts of the plant; they control
different differentiation and developmental events. Any PGR has diverse
physiological effects on plants. Diverse PGRs also manifest similar effects. PGRs
may act synergistically or antagonistically. Plant growth and development is also
affected by light, temperature, nutrition, oxygen status, gravity and such external
factors.
Flowering in some plants is induced only when exposed to certain duration of
photoperiod. Depending on the nature of photoperiod requirements, the plants
are called short day plants, long day plants and day-neutral plants. Certain plants
also need to be exposed to low temperature so as to hasten flowering later in life.
This treatement is known as vernalisation.

“Cell” The structural and functional unit of life

All organisms are made of cells or aggregates of cells. Cells vary in their shape, size
and activities/functions. Based on the presence or absence of a membrane bound
nucleus and other organelles, cells and hence organisms can be named as eukaryotic or prokaryotic.
red blood cell
A typical eukaryotic cell consists of a cell membrane, nucleus and cytoplasm.
Plant cells have a cell wall outside the cell membrane. The plasma membrane is
selectively permeable and facilitates transport of several molecules. The
endomembrane system includes ER, golgi complex, lysosomes and vacuoles. All
the cell organelles perform different but specific functions. Centrosome and centriole
form the basal body of cilia and flagella that facilitate locomotion. In animal cells,
centrioles also form spindle apparatus during cell division. Nucleus contains
nucleoli and chromatin network. It not only controls the activities of organelles
but also plays a major role in heredity.
Endoplasmic reticulum contains tubules or cisternae. They are of two types:
rough and smooth. ER helps in the transport of substances, synthesis of
proteins, lipoproteins and glycogen. The golgi body is a membranous organelle
composed of flattened sacs. The secretions of cells are packed in them and
transported from the cell. Lysosomes are single membrane structures
containing enzymes for digestion of all types of macromolecules. Ribosomes
are involved in protein synthesis. These occur freely in the cytoplasm or are
associated with ER. Mitochondria help in oxidative phosphorylation and
generation of adenosine triphosphate. They are bound by double membrane;
the outer membrane is smooth and inner one folds into several cristae. Plastids
are pigment containing organelles found in plant cells only. In plant cells,
chloroplasts are responsible for trapping light energy essential for
photosynthesis. The grana, in the plastid, is the site of light reactions and the
stroma of dark reactions. The green coloured plastids are chloroplasts, which
contain chlorophyll, whereas the other coloured plastids are chromoplasts,
which may contain pigments like carotene and xanthophyll. The nucleus is
enclosed by nuclear envelop, a double membrane structure with nuclear pores.
The inner membrane encloses the nucleoplasm and the chromatin material.
Thus, cell is the structural and functional unit of life.

WHAT IS ‘LIVING’?

When I try to define ‘living’, I conventionally look for distinctive
characteristics exhibited by living organisms. Growth, reproduction, ability
to sense environment and mount a suitable response come to our mind
immediately as unique features of living organisms. One can add a few
more features like metabolism, ability to self-replicate, self-organise,
interact and emergence to this list. Let us try to understand each of these.
All living organisms grow. Increase in mass and increase in number
of individuals are twin characteristics of growth. A multicellular organism
grows by cell division. In plants, this growth by cell division occurs
continuously throughout their life span. In animals, this growth is seen
only up to a certain age. However, cell division occurs in certain tissues to
replace lost cells. Unicellular organisms also grow by cell division. One
can easily observe this in in vitro cultures by simply counting the number
of cells under the microscope. In majority of higher animals and plants,
growth and reproduction are mutually exclusive events. One must
remember that increase in body mass is considered as growth. Non-living
objects also grow if we take increase in body mass as a criterion for growth.
Mountains, boulders and sand mounds do grow. However, this kind of
growth exhibited by non-living objects is by accumulation of material on
the surface. In living organisms, growth is from inside. Growth, therefore,
cannot be taken as a defining property of living organisms. Conditions
under which it can be observed in all living organisms have to be explained
and then we understand that it is a characteristic of living systems. A
dead organism does not grow.
Reproduction, likewise, is a characteristic of living organisms.
In multicellular organisms, reproduction refers to the production of
progeny possessing features more or less similar to those of parents.
Invariably and implicitly we refer to sexual reproduction. Organisms
reproduce by asexual means also. Fungi multiply and spread easily due
to the millions of asexual spores they produce. In lower organisms like
yeast and hydra, we observe budding. In Planaria (flat worms), we observe
true regeneration, i.e., a fragmented organism regenerates the lost part of
its body and becomes, a new organism. The fungi, the filamentous algae,
the protonema of mosses, all easily multiply by fragmentation. When it
comes to unicellular organisms like bacteria, unicellular algae or Amoeba,
reproduction is synonymous with growth, i.e., increase in number of cells.
We have already defined growth as equivalent to increase in cell number
or mass. Hence, we notice that in single-celled organisms, we are not very
clear about the usage of these two terms – growth and reproduction.
Further, there are many organisms which do not reproduce (mules, sterile
worker bees, infertile human couples, etc). Hence, reproduction also cannot
be an all-inclusive defining characteristic of living organisms. Of course,
no non-living object is capable of reproducing or replicating by itself.
Another characteristic of life is metabolism. All living organisms
are made of chemicals. These chemicals, small and big, belonging to
various classes, sizes, functions, etc., are constantly being made and
changed into some other biomolecules. These conversions are chemical
reactions or metabolic reactions. There are thousands of metabolic
reactions occurring simultaneously inside all living organisms, be they
unicellular or multicellular. All plants, animals, fungi and microbes exhibit
metabolism. The sum total of all the chemical reactions occurring in our
body is metabolism. No non-living object exhibits metabolism. Metabolic
reactions can be demonstrated outside the body in cell-free systems. An
isolated metabolic reaction(s) outside the body of an organism, performed
in a test tube is neither living nor non-living. Hence, while metabolism is
a defining feature of all living organisms without exception, isolated
metabolic reactions in vitro are not living things but surely living reactions.
Hence, cellular organisation of the body is the defining feature of
life forms.
Perhaps, the most obvious and technically complicated feature of all
living organisms is this ability to sense their surroundings or environment
and respond to these environmental stimuli which could be physical,
chemical or biological. We sense our environment through our sense
organs. Plants respond to external factors like light, water, temperature,
other organisms, pollutants, etc. All organisms, from the prokaryotes to
the most complex eukaryotes can sense and respond to environmental
cues. Photoperiod affects reproduction in seasonal breeders, both plants
and animals. All organisms handle chemicals entering their bodies. All
organisms therefore, are ‘aware’ of their surroundings. Human being is
the only organism who is aware of himself, i.e., has self-consciousness.
Consciousness therefore, becomes the defining property of living
organisms.
When it comes to human beings, it is all the more difficult to define
the living state. We observe patients lying in coma in hospitals virtually
supported by machines which replace heart and lungs. The patient is
otherwise brain-dead. The patient has no self-consciousness. Are such
patients who never come back to normal life, living or non-living?
In higher classes, you will come to know that all living phenomena
are due to underlying interactions. Properties of tissues are not present
in the constituent cells but arise as a result of interactions among the
constituent cells. Similarly, properties of cellular organelles are not present
in the molecular constituents of the organelle but arise as a result of
interactions among the molecular components comprising the organelle.
These interactions result in emergent properties at a higher level of
organisation. This phenomenon is true in the hierarchy of organisational
complexity at all levels. Therefore, we can say that living organisms are
self-replicating, evolving and self-regulating interactive systems capable
of responding to external stimuli. Biology is the story of life on earth.
Biology is the story of evolution of living organisms on earth. All living
organisms – present, past and future, are linked to one another by the
sharing of the common genetic material, but to varying degrees.

Photosynthesis

 By looking at a plant externally can you tell whether a plant is C3 or C4?

Usually plants growing in dry conditions use C 4 pathways. It cannot be said
conclusively if the plant is a C3 or C4 buy looking at external appearance, some guess
can be made by looking at fleshy leaf structure.

 By looking at which internal structure of a plant can you tell whether a plant is C3 or C4?

The particularly large cells around the vascular bundles of the C4 pathway
plants are called bundle sheath cells, and the leaves which have such anatomy are
said to have ‘Kranz’ anatomy. ‘Kranz’ means ‘wreath’ and is a reflection of the
arrangement of cells. The bundle sheath cells may form several layers around the
vascular bundles; they are characterised by having a large number of chloroplasts,
thick walls impervious to gaseous exchange and no intercellular spaces.

 Even though a very few cells in a C4 plant carry out the biosynthetic –Calvin pathway, yet they are highly productive. Did you know why?

 C4 plants chemically fix carbon dioxide in the cells of the mesophyll by
adding it to the three-carbon molecule phosphoenolpyruvate (PEP), a reaction
catalyzed by an enzyme called PEP carboxylase and which creates the four-carbon
organic acid, oxaloacetic acid. Oxaloacetic acid or malate synthesized by this process
is then translocated to specialized bundle sheath cells where the enzyme, rubisco,
and other Calvin cyle enzymes are located, and where CO2 released by
decarboxylation of the four-carbon acids is then fixed by rubisco activity to the
three-carbon sugar 3-Phosphoglyceric acids.
The physical separation of rubisco from the oxygen-generating light reactions
reduces photorespiration and increases CO2 fixation and thus photosynthetic capacity
of the leaf.
C4 plants can produce more sugar than C3 plants in conditions of high light and
temperature. Many important crop plants are C4 plants including maize, sorghum,
sugarcane, and millet.

 RuBisCO is an enzyme that acts both as a carboxylase and oxygenase. You know why  RuBisCO carries out more carboxylation in C4 plants?
RuBisCO has a much greater affinity for CO2 than for O2. It is the relative concentration of O2 and CO2 that determines which of the two will bind to the enzyme. In C3 plants some O2 does bind to RuBisCO, and hence CO2 fixation is decreased.
Here the RuBP instead of being converted to 2 molecules of PGA binds with O2 to
form one molecule and phosphoglycolate in a pathway called photorespiration. In the
photorespiratory pathway, there is neither synthesis of sugars, nor of ATP. Rather it
results in the release of CO2 with the utilisation of ATP. In the photorespiratory
pathway there is no synthesis of ATP or NADPH. Therefore, photorespiration is a
wasteful process.
In C4 plants photorespiration does not occur. This is because they have a mechanism
that increases the concentration of CO2 at the enzyme site. This takes place when
the C4 acid from the mesophyll is broken down in the bundle cells to release CO2 –
this results in increasing the intracellular concentration of CO2. In turn, this ensures
that the RuBisCO functions as a carboxylase minimising the oxygenase activity.

 Suppose there were plants that had a high concentration of Chlorophyll b,
but lacked chlorophyll a, would it carry out photosynthesis? Then why do
plants have chlorophyll b and other accessory pigments?

 Though chlorophyll is the major pigment responsible for trapping light,
other thylakoid pigments like chlorophyll b, xanthophylls and carotenoids, which are
called accessory pigments, also absorb light and transfer the energy to chlorophyll a.
Indeed, they not only enable a wider range of wavelength of incoming light to be
utilized for photosyntesis but also protect chlorophyll a from photo-oxidation.
Reaction center chlorophyll-protein complexes are capable of directly absorbing light
and performing charge separation events without other chlorophyll pigments, but the
absorption cross section (the likelihood of absorbing a photon under a given light
intensity) is small. Thus, the remaining chlorophylls in the photosystem and antenna
pigment protein complexes associated with the photosystems all cooperatively
absorb and funnel light energy to the reaction center. Besides chlorophyll a, there
are other pigments, called accessory pigments, which occur in these pigment-protein
antenna complexes.

Natural resources and its conservation

 

 

 

 

Natural resources

Natural resources are those things that formed from the biotic and abioytic factors in the atmosphere, and which are used by man for various purposes. Natural resources are of two types’ renewable resources and non-renewable resources.

 

 

Renewable resource

They can make again and again according to the use.

E.g.: timber, paper, trees, fire woods, food crops etc…..

Non-renewable resources

They can’t be made once they are used up.

E.g.: metals, kerosene, petrol, natural gas, coal, diesel, minerals etc…..

Cause of depletion of natural resources

Man is exploiting the natural resources excessively as part of his existence. The main causes of depletion of natural resources are:

  -population growth

          -deforestation

          -natural calamities like flood and drought

          -over consumption

          -pollution

As population increases the depletion of natural resource will also increase. It is because of the necessary activities of man. Man over exploit natural resources for his comforts. This can ultimately lead to the scarcity of these resources in the near future. This can ultimately threaten the existence of life on the earth.

Due to the deforestation cause the decrease of rainfall and amount of firewood. Due to this, 200 cores of people suffer from the scarecity of water. Besides this, man over consuming the available source of water. This activity will definitely affect future generations.

Today the number of motor vehicles is increasing day by day. This needs a huge amount of petroleum and diesel. One liter of petrol will burned out when a motor car runs about 10 km of distance. How many such vehicles! The fossil fuels have been formed in the earth by steady process of cores and cores of years. Many years required to formulate 1kg of fossil fuels.

If this types of over consumption of fossil fuels continuous, the fossil and fuels will disappear from the world.

Only human constitute the steadily increasing resources. When human population increases, the use of natural resources also increases. Man over exploits natural resource for his comfort. This may lead to scarcity of these resources in the near future. This can ultimately threaten the existence of life on earth.

Man is a virus that destroys the resources, as cancer destroys the humans. Humans destroy the natural resource of the entire world.

Conservation of natural resources

Indiscriminate use of natural resources will be a threat even to the existence of man. But it doesn’t mean that we should not use natural resources. We cannot live without these natural resources. So we must use them patiently and have to conserve it.

The methods for keeping the quantity of natural resources steady without any loss are:

  • Take the responsibility to conserve natural resource.
  • Reduce the consumption of natural resources.
  • Renew in the same time the resource that can be renewed.
  • Use non-conventional energy instead of conventional.
  • Strictly control consumption of resources that are non-renewable.
  • Develop more energy resources.
  • Use smokeless fuel efficient motors.

If we could follow these, it’s a good thing for our future generation.

Trees and Nature

Perhaps the most important ecological function of trees is protecting the land against erosion, the wearing away of top soil due towing and water. Trees make the land fertile and help prevent floods. Trees are the lungs of nature. In addition, they play an important role in global climate and the atmosphere regulation; the leaves of trees absorb carbon dioxide in the air and provide oxygen that is necessary for life. Trees have an unending source of medicines.

But now a days we are facing problem called “deforestation”. The indiscriminate cutting or over harvesting of trees for construction of buildings, for pulp to make paper, or clear the land for agriculture, construction, or other human activities. This will reduce the rate of rain that we get and it will lead to water scarcity.  Global warming is also serious problem occurred due to the deforestation. It is due to the increasing of the amount of co2 in the atmosphere. By the smoke from the factories and by burning of oils, petrol, natural gas etc… The amount of co2 will increase in the atmosphere and there is no much trees for absorb excess co2 in the atmosphere. This will led to global warming.

If this situation continues our earth will reach to its end. All the living organisms will be destroyed. So we have to protect trees. We have to avoid deforestation and follow aforestation. We have to plant more trees. We need plants for our survival. We have to make people aware about the importance of trees. It is our duty to save our earth. So save trees …..Live peace fully  

The yaks

Yaks are widely used in the mountainous regions of the Tibet Plateau as transportation, and are relied upon as the main ingredients of the local diet. There are supposed to be as many as 13 million yaks populating the barren landscape at the foothills of the Himalayas .Yaks are members of the bovine family. They are unique animals that live mainly in Qinghai and Tibet plateau. They are two coated animals with a coat of long hair and a soft under down which sheds annually and is normally gathered. Yaks can weigh over 1200 pounds and have a lifespan of 20-25 years. One Yak produces only about 100gms of hair a year. This is pulled or combed in the spring when the animal moults.The

coarser outer hair and fine inner hair is then separated. Hair varies in color from black (wild yaks) to shades of brown. Most prized is inner down hair from yearling calves with a diameter of 15-17 microns and 4-5 cm in length, the adult down is 18-20 microns in diameter and 3-3.5 cm in length. It feels very soft and downy very like camel hair.

Throughout history, the domesticated yak of central Asia has provided Tibetan herders with wool, leather, meat, milk, and cheese. It is a beast of burden and its

 

dung is used as fuel and fertilizer. There are many of them. The larger wild yak, however, decimated by hunting, is an endangered species. Once widely distributed in the high valleys and plateaus of Tibet and the adjoining mountain country, the wild yak now survives in scattered, isolated herds in the most remote, inhospitable areas. Although officially protected from hunting and commercial trade, its future may depend on suitable reserves with good pastures and efficient protection.

 

The wild yak is a sturdy and bulky ungulate with high lung capacity and a thick coat, which are adaptations to the high-altitude environment of Tibet. The males have imposing, stately horns. Although in the past the animal occurred in a wider area of Ladakh, presently it is confined to the Chhang Chhenmo Valley. The historical distribution of the species was spread as far west as the Gya-Miru area, as indicated by the presence of several pit traps, targeted at wild yak, in the area. Species in the past suffered at the hands of trophy hunters, but competition with domestic livestock for the scarce rangeland resources is presently threatening the animal’s population in Ladakh. There is an estimated population of about 200 wild yaks in the region.

 

Some common birds in of our locality (A study)

Introduction

Birds have always fascinated mankind. They are described as “glorified reptiles” which denote their line of evolution. These warm-blooded vertebrates have a beautiful plumage and very interesting habits like courtship, nest-building, parental care and migratory flights. Their wonderful song calls make our mornings and evenings very pleasant. The branch of Zoology which deals with study of birds is called Ornithology. Dr. Salini Ali is the celebrated ornithologist of India.

Different birds and their habitat

  • House Crow (Crovus splendens)

Body with black plumage, grey around the neck. This is a scavenger inhabiting human dwelling areas and is highly useful to man (Commensal). Male and female are alike and show no sexual dimorphism. Omnivorous (Jungle crow does not have a grey neck). It builds nests and looks after its young ones.

 

 

  • Cuckoo (Eudynamis sp.)

Male shining metallic black feathers with a striking yellowish green bill and blood red eyes. Females are grayish brown and spotted and barred with white. So there is a well marked sexual dimorphism. Male has an attractive song call.  Female has no song. It does not build nests and lays its eggs in crow’s nest and the young ones are hatched and looked after by foster parents. Its song is not heard in winter, but becomes noisy in spring and summer.

 

 

 

  • Pigeons (Columbia livia)  

Commonly called blue-rock pigeon. Color is slaty grey with glistening metallic green, purple, and magenta sheen on neck and upper breast. Two dark bars on wings and a band across the end of the tail. No sexual dimorphism, semi-domesticated. Commensal of man.

 

 

 

  • Mynah (Acridotherus tristis)

Deep brown in color with bright yellow bill and legs. No sexual dimorphism. Always found in groups in groups of 2 to 10. Inhabits human dwelling areas. Builds nest.

 

 

 

  • Parrot (Psittacula krameri)

Commonly called rose-ringed parakeet. Body slender with pointed tail. Feather grass green in color. Male has a black and red collar which is absent in the females. Bill red curved adapted for nut-cracking. Builds nests in hollow tree-trunks, crevices and holes of buildings. Found often in large flocks. It is a popular cage bird and can be taught to talk.

 

 

 

  •  Owl (Bubo bubo)

Commonly called great – horned owl. Large, heavy and robust birds. Color is dark brown, streaked and mottled with tawny buff and black. Head is large and bears two conspicuous black ear-tuffs or horns. Eyes large and round, forwardly directed. Legs fully feathered. Mainly noctural but frequently seen during day time. They feed on rodents and harmful insects pests and so is helpful to agriculturalists and hence has no to be protected.

 

 

 

 

  • Woodpecker (din opium benghalensis)

Commonly called Golden – backed woodpecker. Small bird with distinctive golden – yellow and black plumage above and Buffy white with black streaks below. Entire crown and crest on the head is crimson in male and only party so in the female. Bill long, stout and pointed tongue protrusive and barb- tipped. Tails stiff and wedge-shaped. Wood boring habit.

 

 

 

 

 

  • Sparrow (passer domesticus)

Small bird with upper surface earthy-brown, streaked with black, under parts whitish. Male has a black area on the throat and breast. Feeds on seeds and grains. Unfailing Commensal of man. Nest is a collection of straw and rubbish stuffed into a hole in the wall. Useful to agriculture as it destroys several insects’ pests.

 

 

  • Bulbul (Hypsipetes Ieucocephalus)

Body grey- black or ash-brown. Beak and legs red in color. Head has a crest. Builds nests.

 

 

 

 

  • Kite (Milvus migrans)

Body brown in color. Tail frocked. No sexual dimorphism. Beak sharp, strong and curved. Carnivorous. Lives in the neighborhood of man. Nesting season from September to April.

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