Increasing urbanization can attract unwanted visitors such as wild animals that move into cities due to the loss of their habitat and food resources. As humans encroach on natural habitat, there is little separation between where humans live and where animals live. Further, any type of corridor that connects natural habitat to cities, such as road margins, railways, and telephone lines make it easy for animals to accidentally wander into cities looking for food and suitable habitat. However, in the classic case of “if you give a mouse a cookie,” giving these animals access to the lavish lifestyle of food scraps, urban parks and gardens, and safety from natural predators might make it difficult to get them to leave…
A group of researchers from Spain and Portugal conducted a study to determine factors that favor wild boar presence in cities. Their study focused on the wild boar population in Collserola massif, a 11,000 ha natural area just outside of Barcelona. These boars are moving into Barcelona, establishing populations, and becoming extreme nuisances by ransacking gardens and trashcans, causing increased traffic incidents, and increasing the risk for shared diseases. The researchers looked at a variety of factors that might influence wild boars to move into urban areas and found that natural streams acted as corridors for the boars. Source populations are usually found near streams as these are humid areas with dense vegetation. These streams become corridors as boars move along them in search of food. Boar infestation is highest during the dry months when food is scarce as the boars follow the streams into the city where they can feast on cat food from feral cat colonies, vegetation in urban parks, and trash.
The original management practice was to capture and euthanize the boars, but this strategy is not fully effective at reducing populations if boars prefer city life over the nearby forest. The authors of this study have been working with the city council to ensure that appropriate management efforts are implemented to reduce boar access to cities. Vegetation clearings are applied in a 100 m wide border between the Collserola massif and the city limits in order to reduce connectivity. Since wild boars are attracted to the city due to the abundant food supply, the city is also raising public awareness about the consequences of wild boar presence within cities and encouraging people to buy boar-proof devices when feeding feral cat colonies (which is a whole other issue on its own!).
There are other cities throughout France, Germany, Italy, and Spain that have even worse problems with wild boars moving from natural habitats into cities via corridors. For example, Berlin has been dubbed “The Capitol of Wild Boar” due to the extensive wild boar population and the growing number of attacks on humans. The methodology used in this study might therefore help the city with their planning, to not only reduce the boar population but to also prevent them from entering the city in the first place.
Castillo-Contreras, R., Carvalho, J., Serrano, E., Mentaberre, G., Fernández-Aguilar, X., Colom, A., González-Crespo, C., Lavín, S. and López-Olvera, J. R. 2018. Urban wild boars prefer fragmented areas with food resources near natural corridors. Science of The Total Environment. 615: 282–288.
Sánchez, F. “Wild boars close in on Spanish City of Oviedo.” El País. September 14, 2016.
Vincent, C. “Survival of Europe’s fittest.” The Guardian. October 19, 2010.