Box 10H Urban wildlife: fauna and flora

The heterogeneous structure of the city gives rise to a highly diversified mosaic of dispersed biotopes (Council of Europe, 1982). Cities support a relatively wide variety of plants and animals in comparison to the surrounding countryside. Some are specifically adapted to the urban climate, water and soils, and are an integral part of the urban landscape. More plant species can be encountered in urban spaces than on equally large surfaces of the surrounding areas. Of the approximately 80 to 100 breeding species of birds found in any one area of Britain, for example, about 70 to 80 can be found in cities.

The variety of the urban wildlife is due to two main factors:

  1. the greater diversity of the urban landscape, combining extreme ecological conditions;
  2. the human introduction of non-native species, directly by domestication of plants and animals, and indirectly by transportation of seeds and insects by cargo and cars.

The number of native and alien species is related to the size of human settlements (Table 10.10). Birds, occupying a special position in urban ecological food-chains, require detailed and differentiated habitat conditions. The vegetation structure is undoubtedly the major factor affecting birds in towns, but pollutants such as heavy metals and PCBs also influence bird life. The danger is greater around industrial areas and high traffic lanes. Birds are exposed to direct and indirect effects of air and aquatic pollution through the food-chain. In this way therefore, the number of bird species living in towns and cities can act as an indicator of urban environmental quality.

Source: Falinski, 1971


Table 10.10 - Proportion of native and alien species in villages and cities in Poland

Type of settlement Native (%) Alien (%)
Forest settlements 70­80 20­30
Villages 70 30
Small towns 60­65 35­40
Medium towns 50­60 40­50
Cities 30­50 50­70