What bite marks can tell us: Use of on-fruit tooth impressions to study seed consumer identity and consumption patterns within a rodent assemblage

Abstract

Rodents have a highly specialized dentition, and incisor dimensions are very characteristic within each group. In this study we field-tested a rarely-used methodology – using marks left by rodent incisors in fruits and seeds to identify them. The width of the incisors marks made in Plasticine™ blocks using skulls from museum collections, were compared with the marks left on field-collected fruits and seeds. We confirmed the existence of allometric relationship between incisors width and body size. Furthermore larger and harder fruits showed larger bite marks compared with smaller and soft fruits/seeds, indicating the importance of fruit size and hardness in rodent food-plant selection. Based on tooth width measurements, the results also showed that smaller fruits/seeds are used by fewer rodent species, in comparison to fruits of larger size, these being more likely to be consumed and/or predated. Due to an overlap in body size between species, the method did not provide precise identifications of the rodent species consuming particular items, although it does reduce the likely suite of species responsible. However, when used in conjunction with the more commonly deployed tools, this method is highly viable due to easy use and low cost. Future studies using bite marks images and a greater range of morphological features could increase the precision of this technique.