Avian reproductive strategies exhibit remarkable plasticity in various scenarios, posing challenges in determining the optimal pathway through which parents enhance their reproductive success. we addressed this question by employing structural equation modeling (SEM) analysis in a long-term field survey for the azure-winged magpie (Cyanopica cyanus), which had accumulated datasets for multiple reproductive components, including extra-pair fertilization (EPF), hatching failure, nest predation by predators and conspecific raiders, and offspring starvation. Our initial findings revealed a significant variation of these additional reproductive components with the nest’s reproductive initiation time (RIT). Subsequently, SEM analysis was conducted to investigate the interplay among female and male breeding conditions, cooperative breeding, nest RIT, and individual reproductive success. The results from our SEM analysis suggest that both sexes predominantly rely on conventional reproductive pathways – females tend to favor early RIT while males prefer forming social partnerships with higher-quality females – instead of adopting alternative reproductive strategies to enhance their reproductive success. Furthermore, considering intra-sexual variations in breeding conditions observed in both sexes, our findings also indicate that early RIT may be adaptive for experienced females and those males pairing with higher-quality females; whereas delayed RIT is advantageous for inexperienced females and males with a higher probability of acquiring EPF. Overall, our study demonstrates how integrating various aspects of avian reproduction through multivariate analysis provides a comprehensive understanding of avian reproductive success rather than focusing solely on a single strategy.

In social animals, when conspecific individuals use limited resources differently jealousy will occur. To address whether jealousy is an environmental variable underlying negative evolutionary responses to superior phenotypes, we investigated jealous behaviours in the azure-winged magpie, Cyanopica cyanus, under natural and experimental conditions. Within a triad composed of a feeder, a target and three differently-ranked third-party individuals, the target was fed exclusively to experimentally imitate a scene of uneven resource distribution. Three jealousy-type behaviours were exhibited by the third-party (i.e., raiding and assaulting the target, ingratiating themselves with the feeder) and target (expelling and flaunting the worm to third-party, ingratiating itself with the feeder), respectively, that were significantly affected by their social ranks. It suggests that uneven distribution of limited resources should account for the occurrence of jealous behaviours, and that jealousy may function as a reverse evolutionary force to neutralize the potentially too quick diffusion of superior phenotypic traits.