I am very intrested in Animals, but now a days there are very few animal are left in our earth… so how we can save the extinct animals as well as rainforest animals and so on..

When environmental conditions are no longer conducive to the continued survival of a species, extinction occurs. This fact has been documented throughout recorded history, and has likely been the rule since the beginning of life on this planet. Over 99% of all life that has existed on this planet is now extinct. Humans as an instrument for extinction is a relatively recent occurrence, and their ability to significantly affect environmental conditions has only existed for some tens of thousands of years. The scale of environmental change wrought by humans is rooted in their intelligence. With increased intelligence, came the control of fire and other technologies that led to societal development and civilization. The rise of human civilization was accompanied by an ever increasing rise in population and resource consumption, which unfortunately included many species of plants and animals along with their related habitats. Whether this trend will continue to doom further species to extinction will depend on the evolutionary nature of human civilization. The history of human civilization has shown some tendency of increased concern for the welfare of all members of humanity, and to a lesser degree the welfare of other forms of life. To reduce the present rate of human induced extinction, the balance in societal trends will need to change. Whether the growth of societal trends such as environmentalism, animal rights, and population concern will counter the traditional notions of manifest destiny and lebensraum remains to be seen.

It tends to be a local problem and the locals have the most influence on the outcome, but there are external forces that can have an effect and thus intelligent consumers need to be aware that their buying decisons can have an effect on the global ecology.

To that end understanding where things you buy come from is important.

http://rainforests.mongabay.com/1023.htm

Of course you have to be smart about this.

For instance, do you buy only wine with synthetic corks to save the endangered cork trees?

Well then you are only hurting the people who make a living harvesting cork, because when you harvest cork (~70% of which goes to the wine industry), the trees aren't cut down.
In fact, according to the WWF, harvesting cork out of a cork tree is "one of the most environmentally-friendly harvesting processes in the world,"

Arthur

We're running out of biodiversity, and the problem with losing biodiversity is that you have tipping points where everything goes to hell in a handbasket. It's like your diet, if you lose access to a certain type of food you're okay if you substitute, but if you lose more and more options then you're eventually screwed.

Ecotones are one of the best ways to maintain biodiversity, and the individual action route is really fruitful. Firstly, if when you buy food, try to buy food that's 'natural' to that area. Those natural species can then be homes to all the other local (and natural) species that have evolved in your environment. This is why I'm happy to purchase free-range (non-irrigated) organic buffalo.

I let my backyard grow wild (except I hand-pick rampant weeds that I see everywhere) , because I feel that small 'islands' of normalcy in our stratified cities will allow insects, bird and plants to have pockets of territory they can live and breed naturally. I don't see a need to be slaved to some monoculture of tightly cropped foreign grass.

By allowing Nature to own a plot of land, local extinctions are prevented (or reduced) because the natural land can support some biodiversity. This way, there are native weeds and plants that have a habitat, and thus is a habitat for native insects and their predators.