What makes new housing development unsuitable for house sparrows (Passer domesticus)?

Abstract

As a species closely associated with people and urban areas, the house sparrow (Passer domesticus) was expected to prosper with increased urbanization. Over the past few decades, however, house sparrow populations have decreased in many towns and cities around the world. The most commonly mentioned reasons for these decreases are lack of food, especially invertebrates, and fewer nesting sites and shelters. Given the need to evaluate the role of newly built homes and their effect on sparrow habitat, our overall goal was to evaluate if new housing areas are inhabited with a lower density of house sparrows than old housing areas and, if so, to identify factors responsible for the differences. We carried out observations in 60 small settlements in the greater municipal area of Prague, Czech Republic. Our results indicate house sparrows’ high preference for old parts of settlements and unsuitability of newly built-up areas. Backyard poultry’s presence and sufficient green space were both important factors related to house sparrow abundances. Specifically, house sparrow abundance was highest in sites with 20% to 30% greenery cover (trees and shrubs) and they exploited sites that had backyard poultry. We found no effect of other granivorous birds acting as competitors. Instead, house sparrow abundance was higher where another granivorous species were present. As a measure to sustain greater biodiversity in modern housing development, we suggest increasing trees and shrubs cover in newly built-up areas to a minimum of 20%.