Community-wide masting improves predator satiation in North American oaks

Abstract

Mast seeding, a phenomenon observed in numerous perennial plant species, is highly variable reproduction across years, synchronized among individuals within a population. One major fitness advantage of masting lies in the reduction of seed predation rates, achieved through alternating phases of seed scarcity and abundance that starve and subsequently satiate seed consumers. Proximately, the variability in seed production frequently correlates with weather conditions. Convergent responses among species to weather fluctuations often lead to synchronized masting events across species, which may help with predator satiation, but this hypothesis has been rarely tested. In this study, we address this gap by using 23 years of seed production and pre-dispersal seed predation monitoring in three North American oak species (\emph{Quercus rubra}, \emph{Quercus alba}, \emph{Quercus montana}). We found that spring and summer weather patterns correlated with masting events in all three species, resulting in intraspecific synchrony levels ranging from 0.21 to 0.38, depending on the species pair. Intraspecific masting synchrony facilitated efficient insect starvation in \emph{Q. rubra} and \emph{Q. alba}, while community-wide mast years were necessary for satiation in \emph{Q. montana}. Our findings present a rare empirical test supporting the hypothesis that intraspecific masting synchrony enhances reproductive efficiency by minimizing seed losses to generalist seed predators.