The predictable daytime gathering
During daylight hours, the social lives of Asian elephants (Elephas maximus) appear relatively straightforward. At Lahugala Tank, a large reservoir within the Lahugala Kitulana National Park, their behavior follows observable patterns. The park itself is one of Sri Lanka's smallest, covering about 1,554 hectares, but it is a critical feeding ground. The elephants are drawn to the tank's abundant supply of a semi-aquatic grass, Sacciolepis interrupta, which flourishes in the shallow, silted waters.
Elephant society is matriarchal. Daytime observations typically show family units led by an older, dominant female, composed of her daughters and their calves. Adult males, or bulls, are generally solitary or form small, temporary groups with other males. Their association with the female-led herds is transient. This fission-fusion social structure, where groups merge and split, means the composition of a "herd" seen at any moment is a temporary snapshot of a much larger, more fluid social network. The gathering at Lahugala Tank during the dry season, particularly in July and August, can be substantial, with congregations of over 150 individuals drawn to the food and water.
An alternate society after dark
The development of thermal infrared imaging has allowed researchers to observe elephant behavior without using intrusive artificial lights. Studies using this technology at locations like Lahugala Tank have showed a nocturnal social world that operates differently from the one seen during the day. While daytime interactions are more frequent and visible, the patterns of association change after sunset.
At night, elephants shift their priorities. Foraging remains a primary activity, but social dynamics reorganize. Research in other locations has shown that elephants in human-dominated landscapes often become almost exclusively nocturnal to avoid people. At Lahugala, the infrared cameras reveal that the social networks formed at night are distinct from the daytime matriarchal groups and solitary males. The composition of groups and the individuals they choose to associate with can change significantly. This suggests a second, hidden social life, structured by different needs and relationships that are only expressed under the cover of darkness. This nocturnal activity is part of a 24-hour behavioral cycle that is essential for their welfare.