Camouflage via leaf mottling among North American Erythronium species increases with forest cover and deer abundance

Abstract Premise Camouflage is a common plant strategy to avoid herbivory in sparsely vegetated environments. In temperate deciduous forests, leaf mottling is hypothesized to camouflage the nutrient‐rich leaves of spring‐active understory plants against the sparsely vegetated background of leaf litter. However, tests of this hypothesis remain limited to few species at small spatial scales. Methods I used texture metrics to quantify leaf mottling variation across gradients in canopy cover (as a proxy for leaf background) and deer abundance (as a proxy for herbivore pressure) in five Erythronium species in central and eastern North America. Inter‐ and intraspecific leaf mottling roughness and evenness were quantified from iNaturalist community science observations. I then used ANOVA and multiple regression to determine whether mottling increased with canopy cover and deer abundance, as expected from the camouflage hypothesis. Results Mottling roughness and evenness were greatest in Erythronium species known to occur in forests and diminished (i.e., leaves became less mottled) in prairie and woodland species. Mottling also varied intraspecifically for three species (and nearly so for a fourth), tending to increase with greater canopy cover. This mottling–canopy‐cover relationship was strongest in areas of high to very high deer abundance. Conclusions Greater Erythronium leaf mottling with canopy cover and deer abundance indicates that this trait may act as an herbivore avoidance strategy in forests. While mottling has also been hypothesized to facilitate photoprotection in high‐light environments, minimal leaf mottling in prairie and woodland species suggests photoprotection is an unlikely mechanism for the genus studied here.