The importance of chemical, visual and behavioral cues of predators on the antipredatory behavior of birds

Nesting mortality in birds is caused primarily by predation. The ability to use different predator cues to assess the level of predation risk could be essential to minimize the predation risk during the breeding period. Previous studies show that birds modified their parental behavior when they detected chemical or visual cues of predators in the surrounding of the nest. However, according to the threat sensitivity hypothesis, birds may use more than one predator cue in order to accurately assess the level of predation risk. In this assessment, the behavior of predators can provide important information to evaluate the motivation of the predator to launch an attack. However, there are no studies that examined the importance of chemical, visual and behavioral cues of predators on the antipredatory behavior of birds. We examined the antipredatory behavior of blue tit Cyanistes caeruleus parents when they were exposed to live predators or stuffed models of predators that also had predator chemical cues. Blue tits were able to detect the behavioral cues of predators and exhibited greater antipredatory behaviors when exposed to a live predator than to a stuffed model with chemical cues. The results suggest that birds use the chemical, visual and behavioral cues of the predators to assess the level of predation risk and adjust their antipredatory behavior accordingly.