In the modern promptly changing conditions the natural balance quite often is broken. In a certain area appear or vanish the whole bird species, animals, insects. Often the reasons of change of borders of an area consist in human activity, but sometimes the answer to a riddle of the nature is unexpected.
Instruction
1. Each living organism looks for for itself and the posterity the safe, nourishing and cozy residence. Therefore if a certain place became dangerous, it try to leave, find other territory for dwelling. For example, if near a den of a fox the hunting base appears, she will go to the neighboring forest, thus, borders of an area of a fox will change. About 100 bird species since 1600 were completely destroyed by hunting as were not able to fly and trusted the person - it is a wingless auk, a golubeobrazny dodo, the wandering pigeon and others. Today, if the area is reduced too quickly and ecologists will sound the alarm in time, habitats of rare animals most often begin to be protected, hunting for them is forbidden.
2. Leads to change of the residence also change of a food supply. Intensive deforestation everywhere leads to reduction of areas and even to total disappearance of some species, for example, of a komorsky flying fox or dwarfish hippopotamuses. In America the population of chernonogy polecats as their main food are gophers is sharply reduced – and their destruction is important for agriculture.
3. In general, development of agriculture has a huge impact on areas of living organisms of this area. Use of pesticides and other chemicals, artificial irrigation or drainage, construction of many kilometers fences, spraying of toxic agents for insects and rodents – all this considerably influences the whole populations of plants and animals.
4. Sometimes leads emergence of a large number of competitors, and other types to change of borders of an area. A simple example – weed plants which are for a short time capable to force out cultural landings from a bed.
5. If living conditions become more favorable, look number so increases that there is inevitable a resettlement to those areas where earlier did not even hear about these animals or plants. It is known that Europeans delivered rabbits to Australia, and literally in 10 years they so bred, as today yield losses in millions of dollars, and will get rid of them very difficult.
6. Climatic changes are considered not as such noticeable, but not less effective reason of change of an area. Gradual increase or decrease in average annual humidity and temperature first of all influences plants and insects, then those for whom they are a forage, etc. For example, thanks to global warming in Great Britain a rare butterfly the brown golubyanka had an opportunity to lay eggs on geranium leaves, the season of growth of caterpillars considerably increased, in 20 years their area extended on 80 km.