Ecological and evolutionary significance of bark feeding: implications for mammal and plant

Théodore Lefebvre , Tristan Charles-Dominique, Robert Buitenwerf, Kyle Tomlinson

Bark feeding is a widespread but under-reported form of mammalian herbivory that can buffer herbivores against seasonal food shortages while imposing disproportionate damage on woody plants. Despite its ecological significance, the drivers and adaptations underlying bark feeding remain poorly understood. Here we synthesise evidence for the ecological and evolutionary significance of bark feeding for both mammals and plants, and compile a global inventory of bark-feeding mammals to evaluate patterns across body size, dietary guild, biogeographic distribution and biome. We identify 215 bark-feeding mammal species (45 families, 10 orders), nearly half of which are large herbivores (≥ 5 kg), representing up to 20% of large mammals and 21% of woody plant feeders within those clades. Both current richness and estimated pre-human relative prevalence of bark feeders peak in seasonal systems, especially woodlands/shrublands, subtropical deserts and tropical seasonal forests/savannas. Although bark typically contributes a small fraction of annual intake, consumption often increases during resource bottlenecks, consistent with a fallback-resource strategy; available studies also link bark use to improved physiological condition in some herbivores. For plants, bark feeding can girdle stems, cause mortality, alter regeneration and canopy structure, and shift vegetation composition and openness, with consequences that can cascade to community and ecosystem dynamics. Taken together, bark feeding links seasonal scarcity to selection for dietary plasticity and foraging innovation in mammals, with downstream consequences for niche partitioning and community assembly, while recurrent debarking can impose strong selection on stem traits (e.g., bark structure) and, by filtering recruitment and survival, promote heterogeneous (‘mosaic’) vegetation structure.