One and a half million people live in Barcelona, along with large numbers of regular or occasional visitors. We are, however, not alone. Animals and plants also thrive here. There are hundreds of thousands of residents of different species, all sharing the same space: sparrows, swifts, house martins, little owls, gulls, frogs, geckos, ants, crickets... all of them neighbours of Barcelona's two-legged residents.
Mud nest of barn swallow (Hirundo
The urban ecosystem, like any other ecosystem (forest, sea, farmland, etc.), is made up of a series of animals and plants which live together in the same physical space, which in this case are the streets, squares, terraces, roofs, parks and buildings. These species eat one another; compete with each other; parasite on each other... Very similar to what happens in any ecosystem in the world from the frozen Arctic tundra to parched, scorching deserts.
We spend most of our time in this urban ecosystem. We are accompanied by: ants which take advantage of the remains of food in the kitchen; house martins which build their nests in the façades of our buildings; earthworms which dig their galleries in the city's gardens; crickets which serenade us with their song; tadpoles which swim in the ponds of our parks while they await to turn into frogs; dogs, faithful at our side; canaries which keep us company with their virtuoso song; cats which refuse to lose their hunter instinct; and pigeons which proudly coo high up on their ledges.
Pigeons (Columba livia) on the façade
of Santa Maria del Pi church
Obviously, the most important and determining element of this ecosystem is the human being: creator and modifier of habitats and relief, generator the huge excess of food which attracts a proliferation of species (pigeons, rats, cockroaches, etc.), buyers of pets from around the world, builder of gardens in public and private spaces...the human species is at the same time the generator and regulator of an ecosystem created to suit our needs.
The human being is the most important element
of any urban ecosystem