From among all groups of animals birds are the most recognized one. They are liked, do not evoke aversion or fear. It is easy to spot them, you can watch them long and regularly. In comparison with other animals birds can be easily observed. They are big enough to be seen from the distance of a few hundred meters, often they do not hide from humans, most of them are diurnal, they often make loud and characteristic sounds. For many species even from the distance you can tell their sex and distinguish adult specimens from the young ones. Thousands of amateurs watch birds for pleasure and gather information of scientific value concerning occurrence of birds, changes in their number, their migrations and different aspects of their biology. That is how we know more about birds than other animals.

Researches conducted in various parts of the world show that areas where rare, endangered species of birds live are also places of occurrence of numerous rare and endangered species of other animals and plants. Therefore by learning about bird habitats in need of protection we can mark out areas where protection will secure survival of whole great sets of species, ecosystems most threatened by changes created by humans.

Accordingly, although they are not the most important part of nature birds are the most visible one. Thus we can most easily (quickly and cheaply) identify areas in need of immediate protection. In that way birds are representatives of the whole nature.

Birds are good indicator of the state of environment for the following reasons:

• they directly use resources of natural environment, so that every change within this environment affects their composition of species, location and number;
• they are better than other groups of animals researched in terms of biology, living requirements and links with different components of natural environment;
• they are easy to notice, recognize (species, sex, age) and count, which gives possibility of easy and quick (and thus cheap) as well as frequent verification of their presence and number;
• they commonly occur on large areas, which gives possibility of comparison.

Both number of occurring species and size of population of different species depend on availability and abundance of relevant habitats. Decrease in size of population and dying out of species indicate negative changes within ecosystems. Stable or improving state of indicatory species proves proper relations in natural environment.

If due to our efforts to protect habitats we will succeed in protecting some bird species it will mean that we have managed to preserve or improve state of dozens or even hundreds different species (from great trees to microscopic fungi and bacteria), consequently creating conditions for proper development of crops and farm animals and making environment healthier for us.