Table 1.

Definitions of the four possible digging-related events [play digging, digging, well-digging, and peering at well-digging (Peering)] coded from the videos

Behaviour	Definition
Play digging	Manually scraping the substrate or mud next to open water in an ineffective, playful manner–movements are variable and imprecise, and often involve the whole arm; fingers are held straight or relaxed
Digging	Manually scraping the substrate next to open water; small, controlled movements with slightly bent fingers. Even where a hole is produced, the individual does not drink from it
Well-digging	Manually scraping the substrate next to open water; small, controlled movements with slightly bent fingers. The individual drinks the water that filters into the resulting hole, either directly or with a drinking tool
Peering	Directly looking at another individual well-digging for at least 5 s at a close enough range that enables the peering individual to observe the action in detail; it is indicated by the orientation of the head of the observer when following the actions of the observed individual [in accordance with Schuppli et al. (2016)]