Replacing natural grass with synthetic turf reduces the number of sparrows in cities, according to a study by the universities of Alicante and Valencia
In just four years, the population has been reduced by up to 60%
Experts call for urban planning measures to conserve this species
Alicante and Valencia, Wednesday 19 February 2020
Researchers at the University of ValenciaCavanilles Institute of Biodiversity and Evolutionary Biology and the University of Alicante Multidisciplinary Institute for Environmental Research have found a new reason for the decrease in the number of sparrows (Passer domesticus) in urban areas: the replacement of natural grass with synthetic turf in parks. For four years, they have found that the number of sparrows has been reduced to 60%.
The common sparrow is a species that is associated with humans since Prehistory. However, since the beginning of the twentieth century, its population has fallen dramatically in rural and urban areas throughout Europe due to many factors such as urban pollution, lack of space to nest, difficulties in finding food, diseases and predation. In central London, today it is practically extinct, when in 1925 the chronicles speak about more than one hundred million specimens.
Edgar Bernat-Ponce and José A. Gil-Delgado, of the Cavanilles Institute, and Germán M. López, of the University of Alicante, explain that many European cities have undergone redevelopment processes in recent decades and the effects of this on urban biodiversity are hardly known. In an article recently published in the Urban Ecosystems magazine, they studied for 4 summers (between 2015 and 2018) the impact of replacing the soil of the parks (grass, bare soil) with other artificial components (concrete, artificial grass, areas for dogs, pavements) on the abundance of the common sparrow.
Of the 32 Valencian parks studied in four locations, major remodelling occurred in 10 of them during the four years. In both types of parks, both those that were remodelled and those that finally stayed the same, the abundance of sparrows was similar at the beginning. However, in those that were not renovated during this period, the population declined 15%, while in those renovated the decline reached an average of 60% in the same period, leading to a peak of 62.3% after the year of the replacements.
Among the conclusions of the study, led by Edgar Bernat-Ponce, the remodelling of areas with natural grass is more harmful to sparrows than in areas of bare soil. This is explained by the fact that invertebrates and seeds -food- are much more likely to be present in grass than in areas without plant cover.
The researchers in their study have also measured the distance between the parks, since the remodelling of an urban park could have caused the sparrows to move to another nearby park. With an average distance between parks of 370 metres, most of the birds that disappeared from those urbanised parks either died or migrated to adjacent urban habitats, since it is a species with small roaming areas.
In their research, the three experts ask to implement new urban planning policies with the urgent need to preserve the common sparrow and other birds. However, they are also aware that the measures proposed by the city councils have had the effect of reducing water consumption and cost of the gardens. In this sense, they propose using native trees, or grass species with less water consumption for parks, which would increase the number of invertebrates available for the livelihood of sparrows. They also propose to improve the urban green roof and connect it to help in the movement of birds.
Bernat-Ponce, et al. «Replacement of semi-natural cover with artificial substrates in urban parks causes a decline of house sparrows Passer domesticus in Mediterranean towns». Urban Ecosystems (2020). https://doi.org/10.1007/s11252-020-00940-4
1. Common sparrow. Photo by Jana Marco
2. Edgar Bernat-Ponce and José A. Gil-Delgado, researchers of the Cavanilles Institute of the University of Valencia
3. Germán M. López, researcher of the University of Alicante
Universidad de Alicante Carretera de San Vicente del Raspeig s/n 03690 San Vicente del Raspeig Alicante (Spain)