Temperature and Rainfall Shape the Breeding Ecology of Barn Swallows Hirundo rustica in an Arid Region

Local weather conditions play a critical role in shaping avian reproduction, yet our understanding of these patterns in arid environments, where climate change is expected to increase drought frequency, is limited. This study investigated the effects of temperature, rainfall, and wind speed on the breeding ecology of Barn Swallows (Hirundo rustica) in an arid region of Algeria during 2023 and 2024. Using generalized linear mixed models (GLMMs), we assessed these effects for several life-history traits and breeding parameters including clutch size, incubation duration, hatching success, nestling period duration, and reproductive success. Our results indicate that clutch size decreased seasonally, while incubation duration increased with rainfall and was shorter for second clutches. Hatching success correlated positively with the amount of precipitation and was higher in second clutches. Nestling period duration increased both seasonally and with prolonged incubation. Reproductive success benefitted from greater rainfall but declined as the season progressed and when incubation was extended. Additionally, higher temperatures reduced renesting probability, suggesting that heat may limit Barn Swallows' reproductive efforts. Our results highlight the importance of rainfall in shaping reproductive success and reveal the negative impact of high temperatures on the breeding performance of Barn Swallows in this region. In a context of climate change and increasing drought frequency, these findings underscore the challenges that Barn Swallow populations might face in arid environments in the near future.