The key points for understanding the place and chances of animal wildlife in ecosystem of the city are as follows:

• Wild animal life in the city is present everywhere and abundant - but poor in its variety, and a major part of it is hardly noticeable for us.

How many of them? (e.g. inner Warsaw - plot 52 sq.km)

• Birds:
  69-78 species breeding in density 800-1600 pairs/km sq. (=300-500 kg/km sq.)
  ca 60 species wintering, density 2500-4500 ind/km sq. (=700-1200 kg/km sq.)
• Mammals:
  ca 10 species regularly, density in some city parks - over 50 ind./ha
• Terrestrial invertebrates: (some groups studied, protozoan not included)
  over 800 species recorded in the area
• several thousands (!) of innoticeable animals (mainly insects) per 1 cub.m of the tree crown in city park (= several hundred "creatures" per 100 tree leafs)
• several hundreds of "unvisible" animals /1m sq. of park lawn
• several ten thousands (!) of them per 1 m sq. of soil in city park.

Urban park is full of "invisible" animals (e.g. inner Warsaw)

 

Urban fauna compared to "natural" one (e.g. Warsaw)

• Reduced diversity:
  In the inner city there live 15% of invertebrate species of the region, and 1/3 of breeding bird species
• Increased abundance:
  e.g. Density of breeding bird population in the inner city is 3-4x higher (in biomass - over 5x!) than in rural areas of the region. In winter the ratio is many times higher - the city is attractive as winter quarter.
• Dependence on man:
  e.g. in inner Warsaw 81% of bird population nests in buildings. 49% of the breeding bird population, and 90% of wintering one - depend in significant degree on human food resources.
• Unbalanced proportions:
  urban animal communities are dominated by few super-abundant species (e.g. feral pigeon and house sparrow account 73% of bird community in inner Warsaw). "Natural" communities have much more proportional structure.



Exotic components:

• The "most urban" animals in Central Europe are of non-native origin. E.g.: Domestic mouse, brown rat, feral pigeon, house sparrow, ring dove.
• Pet animals which escaped from domestic breeding, become often components of urban nature. E.g.: in Tokyo 71 feral bird species (20 of them breeding) were recorded recently as successfuly living in free nature.

• Fauna (i.e. wild animals) is important: as a part of urban nature, as a factor of psychological and sanitary environment of people.

• Animals are an active part of the web of organic matter transformations, which is the main natural function of every ecosystem. E.g.: in the centre of Warsaw consumption (daily/sq.km) of total breeding bird population was estimated for energetic equiwalent to 70-120 kg of bread (= ca twice as much of insects), and in winter - 160-260 kg(!)
• Urban vegetation depend on small "invisible" animals: Miliards of them (--->a) live in every sq.m of lawn, in soil and on every leaf. They are one of the main factors affecting soil fertility (by decomposition processes of organic matter), they are harmful vegetation pests, and they are also (e.g. ants, spiders, birds) reductors of pests.

Role in the city

• Sanitary conditions depend on animals:
  Animals, as efficient consumers (see above), utilize big amounts of food refuses and are mobile sources of infections. E.g.: Feral pigeons and flies are potential sources of a dozen man dieases.
  The term "wildlife" does not include parasites (e.g. fleas, bugs) and indoor pests (e.g. pharaoh’s ants, cockroaches, clothes moths), however cities are a site of great numbers of such animals.
• Value for recreation and ecological education: - Animals (both - "visible" and "invisible" ones) make urban landscape "living", which means psychological comfort of city dwellers. Some animals (particularly birds, some mammals, butterflies) are attractive as objects of hobbies (eg. bird watching. feeding). This is important factor of recreation and stimulation of friendly understanding of nature.

• Recent expansion of urban development is responded by accelerated adaptation of wild animal populations to existence in new type of environment - cities. This world-wide phoeno- menon was named "synurbization".

Increasing adaptation to cities

• Urban development destroys a great part of wildlife from original habitats.
  Cities are a new "empty" ecological space, which poses specific limitations and advantages to wild animals. More and more animal species and populations attempt to adopt to these new (urban) life conditions. E.g.: 11-17 new breeding bird species and at least two mammal species settled in inner Warsaw during the last decades. Dozen of bird species distinctly increased their population. Total bird population increased at least by 10% (but its diversity - decreased!).
• New term "synurbization" was coined to name adaptation of wild animal populations to specific urban conditions, which means often colonizing cities by new animal species. Synurbization is an increasing world-wide phoenomenon - it is a response of animal wildlife to global urbanization. Synurbization processes are known mainly in birds and mammals (but also in other animals).
• Synurbic populations show specific differences of ecology and behaviour, as compared with populations of the same species living in non-urban areas. E.g.: - much higher density of population, more sedentary life, prolonged breeding season, changes in circadian activity, increased longevity (but worse health parameters!), increased agression, tameness to man.

Cities are "new" in nature
Age of species of present fauna: 1,000,000-500,000,000 years
Age of urban landscape in global scale: 100-200 years

Terms used in "urban" zoology/ecology:

• Synanthropization: - adjusting of animals to man created conditions
• Synurbization: - adjusting of animals to specific urban conditions (response of animal wildlife to urbanization)
• Urbanization: - changes of landscape (habitat) under urban development

Animals adjust to urban conditions (synurbization)

• Increasing synurbization in animal wildlife is a chance for enriching urban nature, and to minimize negative impact of urbanization. Recent knowlege offers measures for making use of this chance.

Hopeful chance

• Colonizing of cities by new species - increases poor biological diversity of urban ecosystem. Adjusting of animal wildlife to urban conditions is also a chance for coexistence (or for diminishing conflict) between our urban civilization and nature.
• Ability of animal wildlife to adjust to urban conditions, should be considered in managing urban ecosystem. Synurbization processes should be stimulated not only in the aim to enrich biodiversity of urban nature, but also for controlling negative aspects of animals presence (pests, undesirable concentrations). Recent knowlege offers measures for these purposes, but they are not fully used

World ecological crisis affects urban fauna as a whole animal world, in spite of synurbization tendencies. E.g.: In inner Warsaw general diversity of avifauna decreased (ca 20 breeding sp. disapeared) in spite of settling 11-17 new species. Main reasons of these losses were changes of local habitats and general situation of the species in the region. Better adjusting to urban conditions could probably be a chance for some of those birds.





Maciej LUNIAK
Institute of Zoology
Polish Academy of Sciences
Warsaw, POLAND