Manufacture and use of allogrooming tools by wild killer whales

The manufacture and use of tools, while widespread in terrestrial animals¹, has been less frequently reported in marine taxa². In cetaceans, clear examples of tool use are largely restricted to foraging contexts, with no reports of cetaceans fashioning tools by modifying objects. Here, we report evidence of the widespread manufacture and use of allogrooming tools in a population of resident killer whales (Orcinus orca ater).