Changes in the House Sparrow Passer domesticus population in Valencia (Spain) from 1998 to 2008

Capsule The population of House Sparrow Passer domesticus has experienced a sharp decline in the municipality of Valencia. Aims To investigate the population trends of House Sparrows. Methods Between September 1998 and December 2008, House Sparrows were censused monthly in 22 urban parks covering a total of 118 ha. Additionally, birds in the wider urban landscape were censused in 24 plots of about 50 ha during the winter and spring of years 1998, 2003 and 2007. Results The House Sparrow population experienced a significant decline of about 70% over 10 years in urban parks, with monthly peak values decreasing from about 2000 birds in 1998 to about 500 in 2008. Between 1998 and 2007, a significant decline was detected in the urban landscape mostly during the winter. Conclusions Urban parks are a main feeding habitat for House Sparrows, and habitat structure of urban parks has remained similar throughout these years. Therefore, the decreasing number of sparrows recorded in parks probably reflects an overall population decline of the species in Valencia. This decline has coincided with high-intensity urban development i.e. an increase in the building density and a reduction in the amount of wastelands and other feeding habitats. Thus, shortage of nest-sites did not seem to be a limiting factor for the population, but a reduction of food availability may be partially responsible for the observed patterns.