Factors Affecting Flight Initiation Distance in American Robins

Abstract

Both behavioral ecologists and wildlife biologists have shown considerable interest in the responses of animals to approaching humans. Behavioral ecologists have typically viewed humans as a means of simulating predators (reviewed by Lima and Dill 1990, Lima 1998a,b), whereas wildlife biologists have focused on animals' responses to humans because humans are often the major factor in disturbance and may have a particularly strong impact on sensitive species during breeding (Sekercioglu 2002, Taylor and Knight 2003). Animals respond similarly to approaching humans and predators, typically by becoming alert or fleeing, and either response can be costly. Both responses reduce the time available for other activities that benefit fitness (Kohler and McPeek 1989, Scrimgeour and Culp 1994, Hik 1995, Sinclair and Arcese 1995), and individuals that flee expend extra energy. Animals can reduce these costs by assessing risk and responding appropriately. One adjustment that many species make to different levels of risk is to vary flight initiation distance, the distance between an individual and an approaching threat when the individual flees.