Seed predator preferences are associated with seed traits but an unlikely mechanism of local extinction

Certain traits, including those that make species more vulnerable to consumption by predators, may make species inherently susceptible to population declines and local species loss (i.e. extirpation). To examine whether small mammal and arthropod granivory is a mechanism of community change via association with extirpation events, we studied seed predation on six phylogenetically paired extirpated and extant species from Kalamazoo, Michigan, using a seed removal experiment in a restored prairie. We also examined differences in granivore preferences for seed traits (seed mass, water content, C:N content) and differences in seed traits between extirpated and extant taxa. Granivory was independent of extirpation status but was affected by seed traits. Small mammals consumed more seeds than arthropods and preferentially consumed large seeds, while arthropods consumed small seeds and those with higher C:N ratios (lower nitrogen content). Extirpated and extant taxa did not differ in seed traits, perhaps explaining why they did not differ in granivory. Granivory was phylogenetically conserved, suggesting that certain plant families are more susceptible to granivores than others. This study indicates that granivory varies across species and seed traits in a prairie restoration, but does not likely influence extirpation in this system. Understanding granivore preferences may help managers predict establishment success for rare or extirpated species with particular traits being introduced into prairie restorations.