ABSTRACT
This chapter analyses the biological characteristics of the urban habitat, the features common to the urban flora and fauna and the extent to which they vary within the urban and between it and the non-urban habitat. The built environment attains its most complex expression in large, densely built-up urban areas. The increasingly high concentration of population in the large conurbations of the developed world and the very rapid rate of urbanisation in the developing countries have, particularly since the Second World War, focused attention on urban problems and stimulated the growth of urban studies. The wildlife of urban areas is attracting increasing interest related to its scientific, ecological and desirable aesthetic values, and concern about associated problems of pollution and human health. Any consideration of the urban ecosystem must inevitably raise the question of the scale, in terms of the size and degree of habitat diversity, at which a distinct urban biota develops.
