Seed fate and decision-making processes in scatter-hoarding rodents

Amechanistic understanding of seed movement and survival is important both for the development of theoretical models of plant population dynamics, spatial spread, and community assembly, and for the conservation and management of plant communities under global change. While models of wind-borne seed dispersal have advanced rapidly over the past two decades, models for animal-mediated dispersal have failed to make similar progress due to their dependence on interspecific interactions and complex, context-dependent behaviours. In this review, we synthesize the literature on seed dispersal and consumption by scatter-hoarding, granivorous rodents and outline a strategy for development of a general mechanistic seed-fate model in these systems. Our review decomposes seed dispersal and survival into six distinct sub-processes (exposure, harvest, allocation, preparation, placement, and recovery), and identifies nine intermediate (latent) variables that link physical state variables (e.g. seed and animal traits, habitat structure) to decisions regarding seed allocation to hoarding or consumption, cache placement and management, and deployment of radicle-pruning or embryo excision behaviours. We also highlight specific areas where research on these intermediate relationships is needed to improve our mechanistic understanding of scatter-hoarder behaviour. Finally, we outline a strategy to combine detailed studies on individual functional relationships with seed-tracking experiments in an iterative, hierarchical Bayesian framework to construct, refine, and test mechanistic models for context-dependent, scatter-hoarder-mediated seed fate.