Nighttime behavior and the length of social relationships in male Asian elephants.

To evaluate elephant welfare, it is important to understand their use of time both during day and night. The length of social relationships can influence how much time they spend in different activities. We assessed daytime and nighttime activity budgets of male Asian elephants at Denver Zoo and examined how length of relationships influenced nighttime behavior. Using scan sampling we investigated activity budget and proximity to a conspecific, and used General Estimating Equations to compare them across day and night and across new and established dyads at night. During daytime, elephants spent significantly more time exhibiting affiliative and agonistic behaviors, and in proximity to a conspecific, and less time resting, compared to night. Overnight, the odds of resting were significantly lower in new social dyads compared to established dyads, and new dyads spent more time exhibiting agonistic behavior and in proximity to a conspecific compared to established dyads. Our study suggests that male elephants at Denver Zoo have developed strong relationships and highlights the importance of systematically observing elephants overnight so that managers make decisions that improve animal welfare.