Structural equation modeling analysis elucidates the pathways through
which parent birds optimize their reproductive success
Abstract
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.