Integrated Analysis of Morphological and Reproductive Traits Across Reproductive Stages in Mallards (Anas platyrhynchos): Insights into Reproductive Ecology and Success

Seasonal progression of breeding activities in waterfowl is accompanied by marked adjustments in nest construction and reproductive allocation. In this study, I examine how breeding stages shape nest characteristics and reproductive performance in Mallards (Anas platyrhynchos) breeding on Oued Charef Dam Island, northeastern Algeria. Nest dimensions, egg traits, clutch composition, and reproductive success were monitored across successive breeding stages throughout the season. Temporal variation in these traits was analysed using univariate statistical tests (ANOVA with Tukey HSD) and multivariate approaches (Principal Component Analysis and non-metric multidimensional scaling (NMDS). Results indicate a consistent increase in nest size, egg dimensions, and clutch size as the breeding season advanced. Egg volume and mass peaked during the incubation and brood-rearing stages, coinciding with higher hatching and overall reproductive success in later breeding phases. Multivariate analyses revealed that breeding stage strongly structured the observed patterns of reproductive investment, with PCA identifying a dominant gradient of allocation intensity and NMDS confirming its positive relationship with reproductive outcomes. These findings highlight a progressive and coordinated adjustment of reproductive traits in Mallards breeding under semi-arid Mediterranean conditions. The study provides new insights into the temporal organization of reproductive investment in waterfowl and offers a valuable baseline for evaluating the effects of environmental variability and human disturbance on breeding performance.