People feeding porc senglar, or wild boar at the Mirador de Montbau in the Serra de Collserola, above Barcelona (1.6 million people), Catalonia, Spain. Feeding the wild pigs - which can be a dangerous activity, is actively discouraged by the authorities, as it leads to population booms, and the boar also get used to human food, meaning they come into suburban areas to feed at night. In September 2016, researchers from Universitat Autònoma de Barcelona (UAB) plan to start vaccinating some of the port senglars with contraceptives, to cut the population growth. Authorities estimate that the sustainable population for the Parc Natural de Collserola is around 300-400 - however, the current population is could have reached 1,500. Authorities have been hunting the pigs with dogs in order to control the population.