Data from: Large-scale patterns of seed removal by small mammals differ between areas of low vs. high wolf occupancy

Because most tree species recruit from seeds, seed predation by
small-mammal granivores may be important for determining plant
distribution and regeneration in forests. Despite the importance of seed
predation, large-scale patterns of small-mammal granivory are often highly
variable and thus, difficult to predict. We hypothesize distributions of
apex predators can create large-scale variation in the distribution and
abundance of mesopredators that consume small-mammals, creating
predictable areas of high and low granivory. For example, because gray
wolf (Canis lupus) territories are characterized by relatively less use by
coyotes (C. latrans) and greater use by foxes (Vulpes vulpes, Urocyon
cinereoargentus) that consume a greater proportion of small mammals, wolf
territories may be areas of reduced small-mammal granivory. Using
large-scale, multi-year field trials at 22 sites with high- and low-wolf
occupancy in northern Wisconsin, we evaluated whether removal of seeds of
four tree species was lower in wolf territories. Consistent with the
hypothesized consequences of wolf occupancy, seed removal of three species
was more than 25% lower in high-wolf-occupancy areas across two years and
small-mammal abundance was more than 40% lower in high-wolf areas during
one of two study years. These significant results, in conjunction with
evidence of seed consumption in situ and the absence of significant
habitat differences between high- and low-wolf areas, suggest that
top-down effects of wolves on small-mammal granivory and seed survival may
occur. Understanding how interactions among carnivores create spatial
patterns in interactions among lower trophic levels may allow for more
accurate predictions of large-scale patterns in seed survival and forest
composition.