Environment makes major impact on each animal including human. It influences its life and well-being. Factors such as food and water available within the surroundings, the nature of the soil or the salinity of water are parts of environment. These factors when disturbed affect every animal.

Besides, light, heat, cold and various other such factors which we call as climate needs to be suitable for its living. Each animal is equipped with special physical condition to withstand different climatic conditions around the world.

Each of the animal that includes even human has to live and compete with other of it own kind and at the same time with other species. In death, it becomes the food to other living within the same environment.

All animals depend for their existence on an appropriate environment. Many are restricted by their structure and habits to a particular environment. Many have spread from the countries of origin over wide areas of the earth.

Thus they have extended their territories. By doing so they have chosen the areas or surroundings suited to their needs. This has enabled them to develop means to control or reduce in intensity factors in their environment.

For example most of the herbivores give birth to their offspring during or little after monsoon when the food is abundant and carnivores follows next that is after winter when the preys are plentiful.

Therefore, to take care of itself, the first and most important concern of an animal is to secure food in sufficient quantities.