Seasonal Survival Patterns in House Sparrows (Passer domesticus) in Urban Environments: a study case in a Mediterranean city

Abstract

Seasonality, driven by environmental changes, profoundly affects various biological processes in birds, including reproduction, growth, migration, and survival. The urban environment, expanding rapidly due to human population growth, presents challenges for urban birds. House Sparrows, a classic urban exploiter, face long-term population declines with multicausal factors. Limited data on adult and juvenile survival in Mediterranean countries like Spain adds to the complexity. The seasonal survival pattern of a House Sparrow population was studied in an urban ecosystem, a city park of Alcoy Eastern Spain. Ringing was carried out between April 2017 and September 2019 while resighting surveys were carried out until summer 2020. In total, 195 House Sparrows were captured and colour-marked during the four year study period and 145 (74.36%) were recaptured during the survey. Best models showed no differences in seasonal survival between sexes but a reduced survival in summer (end of breeding season). Annual survival shows a decline trend with time that overlaps with the survival seasonal cycle. The preliminary results show that House Sparrow in urban areas presents a negative trend in survival with time and that survival is lower in summer in adults. Our study suggests that urban sparrow decline might be linked to negative trends in survival and that breeding season is very demanding for individuals.