ABSTRACT
The imbalances and stresses created by urban activities have many repercussions. Diseases transmitted from wildlife to humans and from humans to wildlife occur more easily when people and animals share limited space in the absence of natural controls. Some diseases are carried by wildlife and transmitted to people. For instance, rabies is widely distributed in rural areas in North America, skunks and foxes being the principal maintenance hosts. The free movement of animals into cities makes the disease a continuing threat to urban and rural people and is expensive to control. Salmonella occurs in English sparrows during cold weather and can be transmitted to pets and people.12 Some diseases may be carried by pets as well. Toxoplasmosis is particularly infectious to children and is picked up from the faeces of domestic cats in sand-boxes and play areas.13
Urban pets create problems of health and security in crowded city conditions. Feral or stray dogs have been known to attack people; defecation is injurious to plants and is a major source of stormwater pollution. Most major cities regard this as a health hazard, since many older drainage systems discharge stormwater untreated into receiving rivers and lakes in heavy rainstorms. Consequently, overpopulation and uncontrolled breeding, particularly among strays, have become major management problems. The conflicts between people and wildlife range from questions of safety to aesthetics. Birds are hazardous around airports, squirrels damage telephone lines, pigeons make a mess of building cornices and statues in squares, and in Venice they are known to contribute to severe deterioration of stone ornamentation and sculpture on historic buildings. Large flocks of urban gulls can temporarily close down lake beaches because of the pollution they create by defecating. This raises questions about what is valuable or a nuisance, and thus of our perceptions of wildlife in cities.
