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Monday, January 28, 2008

The Creatures of the Dark..!!



How and why do bats hang upside down all day?
Something made me pen down an article on this particular topic. The inspiration was when I was with my boy-friend,sitting on the grassy lawn,near Sanky Tank in Bangalore.It was around 6 o' clock in the evening and what I spotted was a splash of black mass,getting scattered with the rise of moon as the sun set and spreading like a bursting from some hell of black hole. Yes, thats nothing in the sky other than the huge bats. What makes them roost in colonies? Why do they roost and how?

The Name "Bat" comes from Old Norse "ledhrblaka," "leather flapper." It became "bakka" and then "bat."This Indian species, Pteropus giganteus, commonly called as Indian flying fox can be frequently spotted during the day roosting in large colonies, or "camps," high up in the trees. They spend the morning chattering and jockeying for preferred roosting sites on the branches, where they hang by their feet. They pass most of the day asleep with their wings wrapped around themselves. At night they fly to favorite foraging areas, where they feed in the trees on all sorts of ripe fruit (except citrus). The flying fox swallows only the juice, spitting out the pulp.


(The colony of hanging bats during daytime in Talacauvery WLS)



At night, bats swoop through the air, snatching up hundreds of insects and other small animals. But during the day, they hardly move at all. Instead, bats pass the time hanging upside down from a secluded spot, such as the roof of a cave, the underside of a bridge or the inside of a hollowed-out tree.







There are a couple different reasons why bats roost this way. First of all, it puts them in an ideal position for takeoff. Unlike birds, bats can't launch themselves into the air from the ground. Their wings don't produce enough lift to take off from a dead stop, and their hind legs are so small and underdeveloped that they can't run to build up the necessary takeoff speed. Instead, they use their front claws to climb to a high spot, and then fall into flight. By sleeping upside down in a high location, they are all set to launch if they need to escape the roost.





Hanging upside down is also a great way to hide from danger. During the hours when most predators are active (particularly birds of prey), bats congregate where few animals would think to look and most can't reach. This allows them to disappear from the world until night comes again. There's also little competition for these roosting spots, as other flying animals don't have the ability to hang upside down.

http://link.brightcove.com/services/link/bcpid1213900614/bctid1346591910

This is a beautiful link, I remember seeing it in Discovery Channel some years back down the line when I was a student of plant science doing by Bachelors degree.

Bats have a unique physiological adaptation that lets them hang around this way without exerting any energy. If you want to clench your fist around an object, you must contract several muscles in your arm, which are connected to your fingers by tendons. As one muscle contracts, it pulls a tendon, which pulls one of your fingers closed. A bat's talons close in the same way, except that their tendons are connected only to the upper body, not to a muscle. To hang upside down, a bat flies into position, pulls its claws open with other muscles and finds a surface to grip. To get the talons to grab hold of the surface, the bat simply lets its body relax. The weight of the upper body pulls down on the tendons connected to the talons, causing them to clench. The talon joints lock into position, and the bat's weight keeps them closed.

Consequently, the bat doesn't have to do anything to hang upside down. It only has to exert energy to release its grip, flexing muscles that pull its talons open. Since the talons remain closed when the bat is relaxed, a bat that dies while roosting will continue to hang upside down until something (another bat, for example) jostles it loose.

Saturday, January 19, 2008

Why do cats purr?



An Overview

When your cat climbs into your lap, tucks in his paws under himself, and begins to purr, all is right in his world. This is one of the things we love about our cats; that feeling of contentment they share with us. When cats become soft purring bundles of warm reassuring fur, we feel calmer and more peaceful ourselves. We may not always hear the purring – a soft vibrating rumble – but we can feel it. But why do cats purr? And what produces this characteristic sound?

According to veterinarian Bruce Fogle, author of The Cat's Mind, the original function of purring was to enable a kitten to communicate with his mother that things are well. A kitten is able to purr by the second day of life, and although he can't meow and nurse at the same time, he can purr and nurse. And the mother cat often purrs back, probably to reassure the kitty.

There are many theories to explain how the purr is generated. One study determined that purring involves activation of nerves within the voice box. These nerve signals cause vibration of the vocal cords while the diaphragm serves as a piston pump, pushing air in and out of the vibrating cords, thus creating a musical hum. Veterinarian Neils C. Pederson, author of Feline Husbandry, believes that purring is initiated from within the central nervous system and is a voluntary act. In other words, cats purr only when they want to.

Purring is an integral part of the feline communication system and occurs for a variety of reasons. It is classified with the "murmur vocalization" group, which involves sounds produced by a cat while the mouth is closed. In addition to purring, this group of sounds includes grunting, calling, and acknowledgment murmurs. Domestic cats and some wild cats, like pumas and mountain lions (almost any big cat that cannot roar), are all able to purr.

As the cat matures the meaning of the purr changes. Some cats purr to indicate contentment or pleasure, but badly frightened cats and severely ill cats also purr, and so do females while they are delivering their kittens. It is not uncommon for cats to purr when they are close to death. This final purring may indicate a state of anxiety or possibly euphoria, states that have also been described in terminally ill people.

Animal behaviorists believe that when cats purr under stressful circumstances, they are reassuring or comforting themselves, much as humans may sing to themselves or hum when they are nervous. Frightened cats may purr to communicate submissiveness or non-aggressive intentions. A feral cat may purr to signal that he will not attack and other cats need not feel threatened. Older cats may purr when they play or approach other cats, signaling that they are friendly and want to come closer.

A more recent theory about purring is that it is caused by the release of nature's own morphine-like substances (endorphins) in the brain. Since endorphins are released under circumstances of pain and pleasure, this would explain the seemingly ambiguous expression of purring. This theory jives with Pederson's reasoning, that purring is initiated in the brain, and is also compatible with the more mechanical explanations for purring, as endorphins activate one of the main action systems in the brain (so thought is translated into movement). Whatever the explanation for purring, it seems to indicate cats' contentment and is associated with improvement in their affect at times of stress. Purring is one of cats' most endearing qualities.

Why do cats have whiskers?



Also known as "tactile hairs" or vibrissae, whiskers are the long, thick, flexible hairs on a cat's face. These hairs are located in horizontal rows on the whisker pad, the puffy area between the top corners of your cat's mouth and the outer edges of his nose. Whiskers, like hair and nails, do fall out and are replaced. But whiskers are different from the cat's body hair in a few ways:

* Whiskers should never be cut or trimmed.
* Whiskers are two to three times thicker than the cat's hair.
* Whiskers are rooted very deep in the cat's face, in an area rich in nerves and blood vessels.

A cat's whiskers are so sensitive that they can detect the slightest directional change in a breeze.
In addition to having the long tactile hairs on their cheeks, cats also have shorter ones above their eyebrows, on their chin and on the back of their front legs. Since we are most familiar with facial whiskers, let's look at what they are good for. The role played by these whiskers are:

* Navigation
* Mood indication
* Measuring an opening

Whiskers help the cat feel his way around. Whiskers are so sensitive that they can detect the slightest directional change in a breeze. At night, for example, this helps a cat slink its way through a room and not bump into anything. How? The air currents in the room change depending on where pieces of furniture are located. As the cat walks through the room and approaches the couch, he'll know which direction to turn based on the change in air current around the couch.

In addition to having sensory properties, a cat's whiskers are also a good indicator of his mood. When a cat is angry or feels defensive, the whiskers will be pulled back. Otherwise, when the cat is happy, curious or content, the whiskers will be more relaxed and pushed forward.

(See the whiskers positioned in case of relaxed state)

( Whiskers raised in excited, angry state)


But the whisker's primary use is to help a cat judge whether or not he'll fit through an opening. A cat's whiskers are roughly as wide as his body -- sort of a natural ruler. The whisker tips are sensitive to pressure. One might probably notice a cat sticking his head in and out of an opening before he puts his body in. He's judging the width of the opening, and is determining if he can fit into it. An interesting note: cats don't have a true collar bone, like humans. This allows them to turn and twist their way through very narrow openings.

Friday, January 18, 2008

Birds: The Actors in the film of life, "Coevolutionary systems" !!

When organisms that are ecologically intimate -- for example, predators and prey, or hosts and parasites -- influence each other's evolution, we say that coevolution is occurring. Coevolution is a change in the genetic composition of one species (or group) in response to a genetic change in another. More generally, the idea of some reciprocal evolutionary change in interacting species is a strict definition of coevolution.Birds are often important actors in coevolutionary systems. For example, predation by birds largely drives the coevolution of model and mimetic butterflies. Some butterflies have evolved the ability to store poisonous chemicals from the food plants they eat as caterpillars, thus becoming distasteful. This reduces their chances of being eaten, since birds, once they have tried to devour such butterflies, will avoid attacking them in the future. Other butterflies have gradually evolved color patterns that mimic those of the distasteful butterflies (called "models"). It is disadvantageous for the models to be mimicked, because if the mimics become common then most of the butterflies with the model's color pattern taste good, the birds may resume attacking the models. Being tasted and spit out by a bird is a most dangerous experience for a butterfly. Therefore, mimicry presumably leads to a coevolutionary race -- the mimics evolving toward the color patterns of the models, and the models evolving away from the converging mimics. The birds actually may be directly involved in the entire coevolutionary complex, since they may be under selection for better powers of discrimination. Individuals that can tell the mimetic butterflies from the models will gain more nourishment at less cost in time and effort.
Birds, of course, are presumed to be directly involved in many coevolutionary relationships with their competitors, predators, prey, and parasites. The relationship of seed-hoarding Clark's Nutcrackers and Pinyon jays with pinyon pines is a relatively well-studied example; and the evolution of long bills and sickle-shaped bills in some Latin American hummingbirds which match the long or sharply curved flowers from which they sip nectar (and which they pollinate) is another obvious case of coevolution.



The oriental counter parts of the humming birds are the sunbirds that carry out the pollination in flowers like Loranthus.

Hermit hummingbirds and the curved flowers of the genus Heliconia (seen increasingly as horticultural cut flowers) provide widespread and conspicuous examples of the latter phenomenon throughout the lowland moist forests of Central and South America.In the image of the cardinal flower (Lobelia cardinalis) note the long tube which is adapted to the long beak of hummingbirds and the position of the stigma which receives pollen from the forehead of a visiting hummingbird. Note also the red color which hummingbirds learn to search for because many bees cannot see red, thus the nectar in the flower will not be depleted and will be "saved" for the hummingbirds.Hummingbirds (about 320 species in North and South America) and the flowers which they pollinate are a classical example of coevolution. The ancestral hummingbird evolved from a bird similar to a chimney swift. Swifts have short beaks and cannot hover. They feed entirely on insects which they catch in the air. To grasp hummingbird-flower coevolution, one must be able to postulate a series of steps in which from an ancestral bird like a swift, a hummingbird resulted. One must also postulate how a flower pollinated by other methods evolved to become a flower with specialized features that allow it to be mainly pollinated by hummingbirds.



(Loten's Sunbird)


(Flowers specialized to be pollinated by Sunbirds and Humming birds in the Oriental and Neotropical regions)




Many fruit-eating birds, especially in tropical rain forests are coevolving with the plants whose fruits they eat. The birds get nourishment, and in the process the plants get their digestion-resistant seeds dispersed by regurgitation or along with the birds' droppings. Many characteristics of the plants have evolved to facilitate dispersal, and the behavior and diets of the birds have responded to those changes. In particular, the plants have evolved conspicuously colored, relatively odorless fleshy fruits to attract the avian dispersers of their seeds. They are coevolving in response to the finely honed visual systems of the birds; plant species coevolving with color-blind mammalian seed-dispersers have, in contrast, dull-colored but smelly fruits. The bird-dispersed plants often have evolved fruits with giant seeds covered by a thin, highly nutritious layer of flesh. This forces the bird to swallow the fruit whole, since it is difficult or impossible just to nip off the flesh. In response, birds that are specialized frugivores (that is, that do not take other kinds of food) have evolved both bills with wide gapes (so they can swallow the fruit whole) and digestive tracts that can rapidly dissolve the flesh from the large impervious seed, which then can be regurgitated. Never to forget the Extinct Dodo and Calvaria co-evolution where the bird used to aid in seed dispersal and in lieu get its food in Mauritius island. The extinction of Dodo caused the decline in the seed dispersers and thus leading the path for extinction of Calvaria population.


(The extinct Dodo, a sketch)

The most dramatic examples of avian coevolution are probably those involving brood parasites, such as cuckoos and cowbirds, and their hosts. The parasites have often evolved eggs that closely mimic those of the host, and young with characteristics that encourage the hosts to feed them. In response, some hosts have developed the ability to discriminate between their own and parasitic eggs, and various methods of destroying the latter. As one might expect, Brown-headed Cowbirds have their most serious impact on hosts, such as Kirtland's Warblers, that are thought to have only recently been subjected to cowbird attack and have not yet had time to evolve defensive reactions.
Many examples of coevolution in response to competition between bird species can be inferred from studies of dietary habits and bill structures in various guilds of birds. Here, as in the other cases mentioned, direct evidence of coevolution is lacking. It is lacking for the same reason that there are very few cases of plain old single-population evolution actually being observed in nature. The process occurs over hundreds or thousands of generations, and extraordinary circumstances are required for it to be "caught in the act."
Rainforests are forests are characterized by high annual rainfall and are home to two-thirds of all the living animal and plant species on the planet. It has been estimated that many hundreds of millions of new species of plants, insects and microorganisms are still undiscovered.

Tropical rain forests are called the "Jewels of the Earth", and the "World's Largest Pharmacy" because of the large amount of natural medicines discovered there.


(Manjoli, the cloud forest)

In contradiction to popular belief, rainforests are not major consumers of carbon dioxide and like all mature forests are approximately carbon neutral. Recent evidence suggests that the majority of rainforests are in fact net carbon emitters. However, rainforests do play a major role in the global carbon cycle as stable carbon pools. Clearance of rainforest leads to increased levels of atmospheric carbon dioxide. Rainforests may also play a role in cooling air that passes through them. As such, rainforests are of vital importance within the global climate system.






(Kakachi Rain forest)

Tropical and temperate rain forests have been subjected to heavy logging and agricultural clearance throughout the 20th century, and the area covered by rainforests around the world is rapidly shrinking. Biologists have estimated that large numbers of species are being driven to extinction possibly more than 50,000 a year due to the removal of habitat with destruction of the rainforests.

About half of the mature tropical rain forests, between 750 to 800 million hectares of the original 1.5 to 1.6 billion hectares that once graced the planet have already been felled. The devastation is already acute in South East Asia, the second of the world's great biodiversity hot spots. Most of what remains is in the Amazon basin, where the Amazon rainforest covered more than 600 million hectares, an area nearly two thirds the size of the United States. The forests are being destroyed at an ever-quickening pace. Unless significant measures are taken on a world-wide basis to preserve them, by 2030 there will only be 10% remaining with another 10% in a degraded condition. 80% will have been lost and with them the natural diversity they contain will pass away forever.

Currently one the largest economic values of tropical rainforests comes in the form of tourism. People travel both nationally and internationally to experience rain forests firsthand. The economic benefits of tourism are the most promising way in which rainforests may be preserved. (More to continue in the coming posts)

Monday, January 7, 2008

A Tropical Old world Coraciiform Bird, Merops orientalis


"Charms of Green Bee Eater"




'Admirable' is the word for bee-eaters.Bee eaters are known to be small, brightly colored, tropical Old World Coraciiform birds (birds with a strong, sharp bill, fused front toes, and usually bright coloration including- kingfishers, hornbills and bee-eaters)*.Being birds of the sun, none live in Britain. Yet thoroughly attractive birds, they undoubtedly are sleek and graceful, melodious, restrainedly colourful, tractable, confiding and sociable.



The small green bee-eater is no exception to the rule. This is a petite little grass green colour bird no bigger than a sparrow (not more than 17 cm in size). Commonly called as Little Green Bee-eater (Merops orientalis), this bird is a widespread resident and summer visitor in India. Being a near passerine bird of Order Coraciiformes*, it belongs to the bee-eater family Meropidae. The presence of the two elongated central tail feathers is trademark for the adult’s id which are absent in juveniles, otherwise the sexes being alike.

Its green has hints of reddish brown on the head and neck which is ornamented with a prominent black ‘necklace’. The slender bill is slightly curved and could be called long, keeping in mind the size of the bird. The graceful look of the bird is well matched by a pleasant jingling `teet-teet’ or chirpy `tree-tree-tree’ which the bird constantly utters even in flight. They are the noisiest when they conjugate at dawn to roost in thick canopies fluttering and flying in all directions.

The bird has a rather graceful manner of predation making the entire exercise look almost effortless. This bee eater launches an aerial sortie after snapping its prey up in its bill and circling back gracefully on outstretched motionless wings to its perch where the victim is thrashed to death and gobbled up. Just as the name suggests, bee-eaters predominantly eat insects, especially bees, wasps and ants, which are caught in the air by sorties from an open perch. This species often hunts from low perches, maybe only a metre or less high, readily making use of fence wires and electric wires. Before eating its meal, a bee-eater removes the sting by repeatedly hitting the insect on a hard surface.


Their social behavior isn’t gregarious. Unlike most bee-eaters, these are often solitary nesters, making a tunnel in a sandy bank. The breeding pairs are often joined by helpers, thus sometimes forming small colonies, or nest near other bee-eaters. They lay 4 to 8 spherical white eggs. Both the male and the female take care of the eggs. These birds roost communally, lined up on a tree branch. The call is a soft trill.
The ability to look at a situation from another’s point of view was previously believed to be only restricted to the primate world but is also seen with this small eye catchy birdie also.


Often seen in pairs or with folks sitting on phone and electric wires(very common site infact) and fence in open country throughout the Indian subcontinent, this bird is also spotted in forest clearings and cultivated lands, not to leave the urban sightings(in garden and golf course) . This species should not be confused with the Little Bee-eater (Merops pusillus).

(A Little Bee eater, from South African open ground)(Collected from internet)

Migration is limited to seasonal movements depending on rainfall patterns. Conservation status is LC.


*Order Coraciiformes includes birds like rollers/ bluejay; kingfishers; hornbills; hoopoes; motmots; bee eaters; todies

Tuesday, January 1, 2008

A new sun with new rays of hope...!!

(wishing all the readers of this blogpage a great year ahead.. 2008)


A new day starts as the sun rises in the far east... with millions of new tiny rays growing into a great day with the heat rising and slowly setting in the deep sea, far in the west... the land where a newday awaits to born again .. with another day ahead... scattering its bright colorful lovely rays all across the blue sky giving it a tingy, viridian to brown chrome to yellowish orangeviridian red color to slowly cracking into a deep yellow to white aura circled by a sky blue pastel of color... well thatswhat a artist can paint on his canvas....
but capturing the real sorts need great patience... great passion and great enthu....

and thats hope to get a single best sort of the year, well last year thou.. i woke up at around 3 40 in the night andhalf dozing waiting to get the new year's grandsun rising from the Bay of Bengal....



Yup... thats the new sun... of 2008 as for the post schedules.. well thats last year's nearsun... captured in early dawn, in the chilka IB..

"The beauty always lies in the eyes of the beholder..!!

And this stands by to any ecologist and any one who is really concerned about the nature and thou the "MOTHER EARTH".Unless we are into the nature, it can be never ours and thus it goes very true that "Nature is the best healer".- For all thsoe who love the nature, its creatures, its aura, its escasity and who want it to be intact for a holy cause..!!

In the lap of the nature's valuable gift....we and ourco-creatures... !!

The passion for a good sort is the craze for a photographer...
the passion for being in the nature is the cravefor a naturalist...
and to understand the strands of the nature and the game of life, the wide spread diversity of the nature is the aim of an ecologist...
that forms the build up stone for the blog "Amecomania".
- My belief
Amtrips

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