Frugivores flock, but do carnivores follow? Multi-trophic responses to masting in a tropical rainforest

Pulses of plant resources can influence the spatial aggregation and population dynamics of primary consumers, but the extent to which these effects cascade up the food chain to affect secondary consumers remains poorly understood. Mast fruiting events in Southeast Asian dipterocarp forests, for example, are known to impact a wide range of bird and mammal granivores, but it remains unclear whether the predators of these vertebrates are indirectly affected by seed production. Here, we assess bottom-up effects of masting on a suite of primary and secondary consumers in a tropical rainforest in Borneo, using structural equation models to characterize a network of frugivore/granivores and carnivores. The models were parameterized using 10 years of camera trap and seed availability data collected between 2013 and 2024, spanning two major masting events. These models also account for an outbreak of introduced disease (African swine fever) and the reduced abundance of human visitors in the forest during the COVID-19 pandemic. Dipterocarp seed availability was correlated with the intensity of local site use by omnivorous Malay civets (Viverra tangalunga) and bearded pigs (Sus barbatus), but not granivorous murid rodents or pheasants. Leopard cat site use was correlated with murid rodents, but not pheasants. These findings suggest that masting in this ecosystem is associated with site use intensity of some large-bodied primary consumers but not smaller granivores, and therefore did not percolate up the food web to influence the predators of these taxa, in contrast to research from temperate masting systems.