How do the foragers respond to masting?

Submitted by editor on 17 February 2017.Get the paper!

Masting is the synchronous production of large seed crops across individuals within a plant population, and is thought to have evolved (at least in part) as a mechanism to escape seed predators. How does this work? Theory predicts that superabundant, synchronous seed output during masting events decreases the risk of seed predator attack to individual plants. However, the degree of seed escape depends on the manner in which seed predators respond to resource abundance, measured as the rate of seed attack in relation to seed availability or functional response. Unfortunately, the functional responses of seed predators associated with masting tree species are poorly understood, but are presumably contingent upon seed predator traits such as mobility and foraging behaviour, as well as plant traits controlling the magnitude of seed output and synchrony.

Here we investigate and compare the functional responses of different groups of seed predators (birds, rodents and insects) recruiting to Quercus suber and Q. canariensis, two co-occurring oak species in southern Spain.

We found that the studied groups of seed predators responded similarly to seed availability for both oak species, with attack decreasing at a similar rate with increasing seed output. The fact that functional responses were relatively invariant suggests that tree and seed predator species trait variation do not fundamentally alter the nature (strength) of these interactions and therefore the expected benefits of masting via seed escape. 

Xoaquin Moreira

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