Small granivores remove the seeds of 25 plant species at similarly high rates in an old-field plant community

Plant species vary in the number, size, and character of seeds produced; consequently, there is considerable reason for granivores to differentially target the seeds of some species, impacting plant species abundance and coexistence. In an old-field plant community, we set out trays of seeds for 25 plant species to test for the influence of plant species identity, seed size, native status, and time across the growing season on granivory (i.e., seed removal rates). Most seeds (83%), regardless of species identity, were removed by granivores, and removal rates were higher earlier in the growing season. Forb seeds were removed at slightly higher rates than graminoid seeds (∼4% more seeds removed, on average), but seed removal rates were not influenced by seed size or plant native status. Seed removal rate differed for only 4% of plant species pairs and these differences were small (∼3 out of 20 seeds). Seed removal per plant species was not associated with the field abundance of that plant species. Similarly high removal rates of differently sized seeds suggest that several granivore guilds with different size preferences are present in the community. Temporal variation in removal rates suggests a strong influence of seed availability on granivore behaviour.