The functions of tail flicking in birds: A meta-analysis

Tail flicking is a common behavior that can be observed in many bird species. Various studies have investigated this behavior in different contexts such as during foraging, social interactions, or during predator–prey interactions. Nonetheless, there has been no statistical synthesis of results concerning the most commonly hypothesized functions of tail flicking. We conducted meta-analyses of published studies reporting flicking rates of birds in different contexts to identify a general function of tail flicking across species. We found evidence that tail flicking does not serve only one function but most likely has various functions across species. We found the general trend for flicking being a reflection of vigilance and predation risk. Flicking was related to flock size as rates decreased with increasing flock size, which might be related to a decreased individual predation risk in larger flocks. Moreover, we found flicking to be related to body condition and prey flushing. However, effect sizes for these hypotheses were only available from very few studies (body condition k = 2, prey flushing k = 3). Hence, future research concerning these two functions are necessary. Finally, our results suggested that flicking is not used for social communication, as it was not related to the presence of a conspecific or social status of an individual.