Surviving in the city: annual and seasonal survival variation in Mediterranean house sparrows Passer domesticus

Abstract

Seasonal environmental variation strongly influences bird reproduction, growth, migration and survival. The house sparrow, a characteristic urban species, is declining in parts of its native range, yet information on adult and juvenile survival in Mediterranean countries remains scarce. We examined annual (year-to-year) and seasonal survival patterns (between quarters defined by the biology of the species) in an urban population in eastern Spain. A review of published European annual survival estimates revealed a general decline in both adult and first-year survival over time, with lower values typically reported in local studies than in national assessments, suggesting that reduced survival may contribute to ongoing population declines. Robust, geographically representative survival estimates, together with updated productivity (annual reproductive output) data under current urban conditions, such as reduced food availability, limited nesting sites and high pollution levels, are essential to evaluate population trajectories and assess the long-term viability of the species across its European range.