PS 19-264 - Seasonal variation in seed removal by small mammals in northeastern forests

Abstract: Seasonality has implications for community ecology on many different levels, as changing environmental conditions can alter habitat structure, animal activity, and access to resources. For example, granivorous small mammals in temperate forests face seasonal changes in food availability, as plants disperse seeds at different times of year. Winter conditions can also impose metabolic constraints on small mammals, which, when coupled with seasonally-dependent seed availability, may influence foraging behavior. In response to this gap in knowledge, we conducted a small-mammal seed removal experiment through the fall and winter in forests in central New York. We offered three seed species: Lonicera spp., Acer saccharum, and Tsuga canadensis, in three week-long trials in October and December 2022 and January 2023. We hypothesized that seed removal rates would change seasonally due to variation in natural seed availability, metabolic requirements, and amount of small-mammal activity. We conducted our seed removal experiment at 14 long-term monitoring sites throughout a heterogeneous, forested landscape at Hamilton College, and we monitored seed removal activity with all-season camera traps that allowed us to identify seed predators and observe subnivean activity in the winter.




Seed removal varied seasonally, being highest in December (0.266 ±0.0932, mean proportion of seeds removed ± SE) and October (0.256 ± 0.0932), followed by January (0.187 ± 0.1048). Regardless of season, Lonicera spp. seeds were removed most frequently (0.5037 ± 0.1735), followed by A. saccharum (0.3392 ± 0.1233) and T. canadensis (0.0746 ± 0.0363). The most common seed predators across all seasons were Peromyscus spp. (n = 224 videos). Tamiasciurus hudsonicus also appeared in all months (n = 35 videos), while Tamias striatus was only present in October and December (n = 2 videos). These preliminary results support the hypothesis that overall seed removal changes seasonally. However, the consistent pattern of high Lonicera spp. removal is interesting, as Lonicera spp. is an invasive shrub in this area. Overall, the observed patterns of seed removal across fall and winter highlight the importance of multi-season studies in capturing seasonal variation in foraging behavior.