Urban animal: exotic encounters

Apart from plants from other parts of the world that are invading the urban landscape, there are also exotic animals that have made the city their new home. These are often adaptable species that have escaped captivity or have been released into the wild by former owners (the urban legends about crocodiles and pythons in the sewers stem from these practices).

The Gray Squirrel can be found all over England (Sciurus carolinensis) is native to the eastern and midwestern United States.  This Eastern Grey Squirrel was introduced to England in 1876. The introduced species has few natural enemies and is slightly bigger in build. With a diet similar to that of the native Red Squirrel it is outcompeting this species. Many parks in England are now inhabited by Gray Squirrels only. The Egyptian Goose (Alopochen aegyptiaca) originated in Africa. They are not true geese, but take a position between true ducks and geese. Escaped captive birds have been breeding freely in the Low Countries since the 1960s and their numbers are still growing, especially it seems in the urban environment. The Ring-necked Parakeet (on the right) is another escapee. These birds (Psittacula krameri) originated in Africa and Asia. In most European cities there are feral populations of these vocal birds. Conversely natural populations are declining due to human influence.

Exotic bird species are most common in the urban environment. The very beautiful Mandarin Duck (middle) are to be found in the wild in China and Korea, but these perching ducks (Aix galericulata) have been bred in captivity for centuries. They prefer wooded areas with shallow lakes and marshland. An ideal species to populate urban parks in short. Chinese Geese can also be found on still and flowing water. These large birds (Anser cygnoides domesticus) are the domesticated form of the Swan Goose. The white form is often bred in captivity. Here a large group floating on the Kleine Dommel river in an urban park. There are also some exotic fish populating the waterways and ponds of our urban landscape. Most are rarely seen, except for feral populations of the Goldfish (Carassius auratus  auratus). These ornamental carp were originally bread in China for water gardens. They were introduced to Europe in the 17th century.  Like their wild ancestor the common goldfish can survive in any pond that doesn't freeze completely. Most feral goldfish were dumped in ponds or canals by pet owners, some have escaped from ponds after heavy flooding. The bright colour often fades as the fish reproduce outside cultivation because brightest fish are often eaten - they are easy prey for, for instance, herons.