Category Plants & Animals

          When they first hatch from the egg, baby birds are called nestlings. At this stage, many of them have no feathers. Blind and helpless, they are completely dependent on their parents for food and protection. As their feathers grow, they become fledglings, with open eyes and hearty appetites. When the fledglings have all their feathers and are strong enough, they are ready to learn to fly and begin to be independent.

          Fledging is the stage in a flying bird’s life between hatching or birth and becoming capable of flight. This term is most frequently applied to birds, but is also used for bats. For antiracial birds, those that spend more time in vulnerable condition in the nest, the nestling and fledging stage can be the same. For precocial birds, those that develop and leave the nest quickly, a short nestling stage precedes a longer fledging stage.

          All birds are considered to have fledged when the feathers and wing muscles are sufficiently developed for flight. A young bird that has recently fledged but is still dependent upon parental care and feeding is called a fledgling. People often want to help fledglings, as they appear vulnerable, but it is best to leave them alone. The USA National Phenology Network defines the phenophase (or life cycle stage) of fledged young for birds as “One or more young are seen recently departed from the nest. This includes young incapable of sustained flight and young which are still dependent on adults.”

          In many species, parents continue to care for their fledged young, either by leading them to food sources, or feeding them. Birds are vulnerable after they have left the nest, but before they can fly, though once fledged their chances of survival increase dramatically.

          One species, the ancient murrelet, fledges two days after hatching, running from its burrow to the ocean and its calling parents. Once it reaches the ocean, its parents care for it for several weeks. Other species, such as guillemots and terns, leave the nesting site while they are still unable to fly. The fledging behavior of the guillemot is spectacular; the adult leads the chick to the edge of the cliff, where the colony is located, and the chick will then launch itself off, attempting to fly as far as possible, before crash landing on the ocean.

Picture Credit : Google

          Birds are specially adapted for flight, whether skimming short distances between branches or flying for weeks at a time above the oceans. The shape of their wings gives a clue to the kinds of flight they make. Birds’ bodies need to be light enough for flight. The large surface area of their wings pushes air downwards as they flap to lift the bird. At the same time, birds need immensely powerful chest muscles to move their wings. Feathers are the ideal covering —they are light but strong and flexible. In flight, they can lie flat against the bird’s body to reduce wind resistance.

          Flying is possible for birds because of their strength, speed, weight and the way their bodies are created with parts such as wings. These are adaptations, or special and different features, that are designed to help birds fly. There are many different birds with different ways of flying.

          When you look outside, you probably see lots of different birds flying and soaring from place to place. Their wings flap and help them to fly high in the air. Then, their wings spread out in a strong, straight line to continue soaring.

          Birds’ bodies are usually lighter in weight than other animals. This is a necessary adaptation that helps them fly. Gravity is an invisible force that pulls heavier objects down toward Earth more than lighter objects. Therefore, the light weight of birds makes it easier for them to move up into the air since less gravity is working against them.

          Birds’ weight is also focused toward the center of their bodies. They don’t have too much weight on the sides, front and back of their bodies. This gives them the balance they need to fly.

          Your bones are thick and heavy. However, birds’ bones are hollow, or empty, on the inside, which causes less weight. They also have very light feathers. Mother birds lay eggs instead of carrying babies in their bodies, which helps them to stay lighter in weight as well. Additionally, birds have beaks instead of heavy teeth and noses; this also helps to reduce their weight.

          Have you ever walked around with a heavy, full stomach from eating too much? This causes you to feel heavier. Birds, on the other hand, eat lightweight foods such as berries, seeds and light meats that digest very quickly. Their bodies also get rid of wastes quickly so that they’re not too weighed down to fly.

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          Some male and female birds of the same species have very different plumage, with the male usually being more brightly coloured to attract females. Other species show little or no difference between the sexes. As well as having different plumage, birds may make displays to each other during the breeding season. Some dance in elaborate curving patterns, spread their feathers and strut, or sing. Male birds may fight to defend their territories during nesting.

          Once a budgie is a few weeks old, you will be able to tell the sex of the bird by looking at its cere (the nose and nostril area). In normal circumstances, a hen’s is brown, and a cock’s is blue. The hen’s cere becomes enlarged and scaly during the breeding season, and the male’s becomes a darker shade of blue. Simple!

          But there are a few complications. Hens sometimes have a light blue cere, when their breeding hormone levels are low. It will also be this colour, or white with just a hint of blue, if the bird is ill. In the wild the female’s cere is light blue, turning brown during the nesting season. In young hens, the cere is a light blue with white around the nostrils.

          Cock birds, although nearly always sporting a blue cere, may have a brown or brownish-pink one if his breeding hormones dip, or if he is ill. An ill male may develop a yellow-greenish tinge around the nostrils too. In immature cock budgies the cere is a blueish pink or light purple.

          Some budgie types are harder to sex. Albino, Lutino and Mottled birds, for example, have off-white, light pink or bluish pink ceres, and males of some of the pied varieties have light pink, blueish pink or white ones. With hundreds of variations on the basic types mentioned in the Budgie types section , there is always a chance that your bird will have an ‘ambiguous’ cere colour. In 90% of cases, however, the brown-or-blue rule applies.

          In spite of these complications, cere colour is still the easiest way of sexing budgies. There are a few gender-related differences in voice and behaviour, too; but these are not as consistently ‘male’ and ‘female’ as cere colour. If you inherit an adult bird of unknown sex and with an ambiguous cere, watch out for bonding behaviour – any excessive head-bobbing is likely to be a male and any excessive squawking, rather than chirruping and singing, is probably female.

          Many snakes throw themselves along the ground in waves that pass from head to tail. They have hundreds of pairs of ribs and strong muscles to enable them to do this, while their scales grip the ground. North American sidewinders, however, move as their name suggests, by throwing their coils sideways along the ground. Snakes have four ways of moving around.  Since they don’t have legs they use their muscles and their scales to do the “walking”.

Serpentine method:  This motion is what most people think of when they think of snakes.  Snakes will push off of any bump or other surface, rocks, trees, etc., to get going.  They move in a wavy motion.  They would not be able to move over slick surfaces like glass at all.  This movement is also known as lateral undulation.

Concertina method:  This is a more difficult way for the snake to move but is effective in tight spaces.  The snake braces the back portion of their body while pushing and extending the front portion.  Then the snake drops the front portion of their body and straightens a pulls the back portion along.  It is almost like they through themselves forward.

Sidewinding: This is a difficult motion to describe but it is often used by snakes to move on loose or slippery surfaces like sand or mud.  The snake appears to throw its head forward and the rest of its body follows while the head is thrown forward again.  (See picture.) 

Rectilinear Method:  This is a slow, creeping, straight movement.  The snake uses some of the wide scales on its belly to grip the ground while pushing forward with the others.

Picture Credit : Google

          It is likely that birds evolved from reptiles. Like reptiles but unlike most mammals, they lay eggs that hatch outside the mother. All adult birds have feathers, rather than fur or scales, and most can fly. However, birds are similar to mammals in being warsm blooded.

          When one thinks of the differences between mammals and birds, the first thing that comes to mind is that mammals give birth to their young whereas birds lay eggs. Now let us look at other differences between mammals and birds. The birds have feathers whereas mammals have only fur or hair. This feature is one of the main features of birds that differentiate them from mammals. Birds use feathers for controlling body temperature, flying, and attracting the opposite sex.

          As birds need to fly, they have porous or hollow bones. In contrast, mammals have denser bones. Birds have wings although mammals have paws, hands, and hooves. There is also a difference in the feeding of the young. Mammals feed their young milk produced by the mammary glands. On the other hand, young birds are fed by the parents regurgitating partially digested food.

          Birds and mammals have a larynx. The mammals produce sounds using the larynx. In birds, this organ does not produce sounds. Instead of using the larynx for sound, birds have a syrinx which serves as a voice box. The lungs of birds do not expand or contract as that of the lungs of mammals. In mammals, the oxygen and carbon dioxide is exchanged in the alveoli which are microscopic sacs in the lungs. In birds, the exchange happens in air capillaries which are walls of microscopic tubules. While there is only a single respiratory cycle in mammals, there are two cycles in birds.

          Now comparing the blood, birds have a nucleus in the RBS whereas it is not generally seen in mammals. If there is a nucleus in the RBS in mammals, then it is a sign of sickness. The RBS of birds are oval in shape whereas most of the mammals’ RBSs have a round shape.

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          The chameleon is able to change colour to match its surroundings by releasing or tightening special cells on its skin. As well as this remarkable ability, chameleons are amazing in other ways. They are able to grip very strongly with their toes and tails to balance on precarious branches. Their extraordinary tongues, which are able to shoot out as far as the chameleon’s body length, are sticky and able to scoop back prey like a piece of elastic. Finally, the chameleon’s eyes are bulging and can move in any direction, protected by an eyelid that is fused all-round the eye, leaving only a tiny hole in the middle. Even stranger, the chameleon can move each of its eyes in a different direction at the same time!

          Chameleons are famous for their quick color-changing abilities. It’s a common misconception that they do this to camouflage themselves against a background. In fact, chameleons mostly change color to regulate their temperatures or to signal their intentions to other chameleons. Since chameleons can’t generate their own body heat, changing the color of their skin is a way to maintain a favorable body temperature. A cold chameleon may become dark to absorb more heat, whereas a hotter chameleon may turn pale to reflect the sun’s heat.

          Chameleons will also use bold color changes to communicate. Males become bright to signal their dominance and turn dark in aggressive encounters. Females can let males know if they’re willing to mate by changing the color of their skin. Owners of chameleons can learn to read their pet’s mood based on the color of its skin.

          So how do they pull off these colorful changes? The outermost layer of the chameleon’s skin is transparent. Beneath this are several more layers of skin that contain specialized cells called chromatophores. The chromatophores at each level are filled with sacs of different kinds of pigment. The deepest layer contains melanophores, which are filled with brown melanin (the same pigment that gives human skin its many shades). Atop that layer are cells called iridophores, which have a blue pigment that reflects blue and white light. Layered on top of those cells are the xanthophores and erythrophores, which contain yellow and red pigments, respectively.

          Normally, the pigments are locked away inside tiny sacs within the cells. But when a chameleon experiences changes in body temperature or mood, its nervous system tells specific chromatophores to expand or contract. This changes the color of the cell. By varying the activity of the different chromatophores in all the layers of the skin, the chameleon can produce a whole variety of colors and patterns.

          For instance, an excited chameleon might turn red by fully expanding all his erythrophores, blocking out the other colors beneath them. A calm chameleon, on the other hand, might turn green by contracting his erythrophores and allowing some of the blue-reflected light from his iridophores to mix with his layer of somewhat contracted yellow xanthophores.

          With these layers of cells, some chameleons are capable of producing a dazzling array of reds, pinks, yellows, blues, greens, and browns. These bold statements won’t help them blend into the background, but they will allow them to get their message across to other chameleons loud and clear.

Picture Credit : Google