Large-scale disturbances such as ice storms are predicted to increase in frequency and intensity under many climate change models. While disturbances are a natural component of forest ecosystems, climatically driven alteration to historical patterns may impart fundamental change to ecosystem function. A novel project at Hubbard Brook Experimental Forest, NH, applied experimental ice storms of varying severity to replicate northern hardwood plots to develop an empirical understanding of their effects on forests. As part of this experiment, we quantified effects of ice storm treatments on leaf-feeding Lepidoptera (caterpillars). As the most important herbivores in temperate forests, not only does this group performs vital ecosystem services, they serve as a critical food source for breeding birds. Natural enemies, including invertebrate predators, parasitoids, and insectivorous birds, help regulate their populations. As such, understanding dynamics of these groups after ice storms will aid in forest management and conservation following or in preparation for the predicted increase in frequency of these disturbance events. To assess responses to ice storm damage, we deployed and retrieved plasticine model caterpillars and estimated predation from characteristic ‘wounds’ to these surrogates. Insectivorous bird activity and identity were measured using point counts.
Pre-icing baseline data showed that 202 of 800 caterpillars (25.3%) were predated by birds (n = 63), invertebrates (n = 123), and small mammals (n = 23). We recorded 330 bird observations from 18 species. We predict that caterpillar predation and insectivorous bird use of iced areas will increase due to additional structural heterogeneity after icing. Comparison among predators (bird, invertebrate, small mammal) and functional bird groups (insectivorous vs. other) will provide us with information about their response to disturbance.