Clutch and egg size variation, and productivity of the House Sparrow (Passer domesticus): effects of temperature, rainfall, and humidity

Abstract

This study was conducted on the campus of the regional department of the forestry service, encompassing 2.25 ha in Antalya city center. The area has gardens and is surrounded by trees, providing nesting and feeding opportunities for many songbird species. The study aimed to determine clutch and egg size variation, breeding success, and productivity of the House Sparrow (Passer domesticus), in terms of clutch size and breeding attempts, and to evaluate variation in temperature, rainfall, and humidity in terms of breeding attempts and years, and their possible effects on given parameters of the species. In total, 2016 eggs were laid in 393 clutches and clutch size varied from 1 to 11 eggs; the clutches most commonly contained 4-6 egg in the 3 consecutive years. Mean egg length, width, weight, volume, and sphericity index were 21.16 ± 0.03 mm, 14.99 ± 0.01 mm, 2.02 ± 0.01 g, 2.38 ± 0.01 cm^{3}, and 71.01 ± 0.09, respectively. Breeding attempts were affected by temperature (r = 0.97 P < 0.0001) and rainfall (r = -0.84 P < 0.001). Egg length was affected by rainfall (r = 0.60 P < 0.041), humidity (r = 0.59 P < 0.044), and temperature (r = -0.81 P < 0.002), and egg volume was affected by temperature (r = -0.68 P < 0.015). This study shows that the House Sparrow population in the study area exhibited important variation in clutch and egg size, which was affected by changes in temperature, rainfall, and humidity.