Nocturnal behavior of orphaned Asian elephant (Elephas maximus) calves in Sri Lanka.

Many animals exhibit circadian variation in behavior; thus, studying nocturnal behavior is important to fully understand species activity patterns. The nocturnal behavior of Asian elephants, and specifically calves, has received little previous study. We carried out observational study of the nocturnal behavior of orphaned Asian elephant calves at three age groups: "infant" (0-24 months), "young juvenile" (25-36 months) and "old juveniles" (over 36 months). Project aims were to build a nocturnal activity budget, to investigate key age differences, and whether calves exhibited synchronous behavior patterns. We carried out focal animal sampling and instantaneous group scan sampling on 34 calves for 18 nights using an infra-red camera. Focal results indicated that calves spent the highest percentage of scans in lying rest (46.2%) and feeding (28.4%). There was no significant difference between lying rest in the three age groups. Calves spent the majority of time within 5 m of their nearest neighbor, with infants remaining in closest proximity to conspecifics compared to older calves. Synchronous behavior could not be proved statistically but two distinct lying rest periods between 2300 and 0100, and 0330 and 0530, were noted. We found that calves spent more time in lying rest than previously observed in adult elephants. Activity patterns observed suggest that the orphaned group behavior is similar to that reported in the wild and captive zoological collections, and appears to be in concordance with "natural" behavior patterns, a defining feature of animal welfare. This research provides valuable data as a preliminary study.