Factors Influencing Travel Order as Proxy for Leadership and Trade-offs in Activity Budgets in Lactating and Nonlactating African Savanna Elephants
Nutritional and energetic needs of female mammals depend upon size or reproductive investment and shape individual activity budgets and behavioral patterns. To maximize nutritional and energetic intake females may increase time allocated to foraging or access resources through risk-prone behaviors, represented as aggression or leadership. Conversely, to minimize nutritional and energetic spending females may engage in risk-averse activities such as resting or nonaggressive social interactions. Females with the highest needs should exhibit activities and behaviors that facilitate the greatest nutritional and energetic returns or highest metabolic savings. The propensity for risk-prone behaviors may be greater among older as well as lactating females. Older individuals tend to be larger and more experienced than younger conspecifics. Moreover, lactating females are under substantially greater energetic, nutritional and water stresses than nonlactating individuals. Therefore, to fulfill greater nutritional and energetic needs, older and lactating females may allocate more time to foraging or rest or be more assertive during search for and defense of resources. I assessed the relative effects of age, reproductive condition and sex of nursing offspring on activity budgets, the frequency of risk-prone and risk-averse behaviors such as leadership propensity, and chemosensory inspection of the surroundings in female African savanna elephants (Loxodonta africana africana). To quantify activities and behavioral patterns I used focal animal sampling with continuous recording. I determined leadership by the position in a mobile herd, where the first and last positions were considered as ends, and the center was considered as a middle position. I discovered that older females stood more, were more aggressive, socialized less and traveled closer to the end of a traveling group than younger females. Females that were lactating spent more time foraging, were more aggressive and engaged in nonaggressive social interactions less frequently than their nonlactating conspecifics. Finally, females nursing female calves spent more time foraging than females nursing male calves, but the latter spent more time nursing and standing. These results elucidate how individual nutritional and energetic needs influence the activity budgets as well as the propensity to exhibit risk-prone and riskaverse behaviors in female elephants and thus add to a body of work examining mammalian female activity budgets shaped by individual differences such as age and reproductive condition.
mammal metabolic requirements, Addo Elephant National Park South Africa, mammal nutritional needs, Life Sciences, Other Animal Sciences, Other Nutrition
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