Diets and defenses: an examination of elephant foraging selection in Mapungubwe National Park, South Africa

Elephant populations in southern Africa have dramatically increased
recently, impacting vegetation structure and reducing tree diversity. We observed
and analyzed elephant foraging behavior to determine patterns in browsing
preference for male and female elephants in three age classes in relation to forage
characteristics. Elephants selectively browsed, generally preferring mechanically
defended tree species to those with chemical defenses. Elephants targeted trees
between 4 and 8 m tall significantly proportionally more frequently than any other
size tree, lending more evidence that elephants are fundamentally changing
vegetation structure. Females tended to have more selective diets due, we
speculate, to their physiology than did males, and adults had a much greater
impact on their environment than did juveniles or infants. Elephants have a
significant effect on the vegetation structure in their environment, and the
increasing populations are cause for concern. Patterns in environmental impact
according to sex and age are necessary to inform decisions on elephant
management, while patterns regard plant susceptibility are helpful in predicting
changes in vegetation structure and composition.

近期，非洲南部的大象种群数量大幅增长，对当地植被结构造成显著影响并降低了树木多样性。本研究通过观察与分析大象的觅食行为，旨在探究三个年龄组的雌雄大象在觅食特征相关的取食偏好模式。结果显示，大象具有选择性取食行为，通常更偏好具备机械防御机制的树种，而非化学防御型树种。大象对树高介于4至8米的个体的取食频率显著高于其他尺寸的树木，这进一步佐证了大象正从根本上改变植被结构。我们推测，相较于雄性大象，雌性因生理特征而表现出更强的取食选择性；成年大象对环境的影响也远大于亚成体与幼象。大象对其栖息环境的植被结构具有显著影响，种群数量的持续增长令人担忧。明确按性别与年龄划分的环境影响模式，可为大象管理决策提供科学依据；而与植物易感性相关的取食模式，则有助于预测植被结构与组成的变化。