Recreational activity, nature experience, observation and patience
Bee lining is an ancient technique used to find bee colonies. People used to do this in Europe and it's still common in other parts of the world today. An overview of the diverse methods from different countries and times is given by Eva Crane in her extensive book The World History of Beekeeping and Honey Hunting. More details about the methods and tools can be found in books or articles by Lockard, Donovan, Wenner and Seeley. Those books explicitly focus on the topic of bee-lining.