On the Meaning of Alarm Calls: A Review of Functional Reference in Avian Alarm Calling

Abstract

A long‐standing question in animal communication is whether signals reveal intrinsic properties of the signaller or extrinsic properties of its environment. Alarm calls, one of the most conspicuous components of antipredator behaviour, intuitively would appear to reflect internal states of the signaller. Pioneering research in primates and fowl, however, demonstrated that signallers may produce unique alarm calls during encounters with different types of predators, suggesting that signallers through selective production of alarm calls provide to conspecific receivers information about predators in the environment. In this article, we review evidence for such ‘functional reference’ in the alarm calls of birds based on explicit tests of two criteria proposed in Macedonia & Evans’ (Ethology 93, 1993, 177) influential conceptual framework: (1) that unique alarm calls are given to specific predator categories, and (2) that alarm calls isolated from contextual information elicit antipredator responses from receivers similar to those produced during actual predator encounters. Despite the importance of research on birds in development of the conceptual framework and the ubiquity of alarm calls in birds, evidence for functionally referential alarm calls in this clade is limited to six species. In these species, alarm calls are associated with the type of predator encountered as well as variation in hunting behaviour; with defence of reproductive effort in addition to predators of adults; with age‐related changes in predation risk; and with strong fitness benefits. Our review likely underestimates the occurrence of functional reference in avian alarm calls, as incomplete application and testing of the conceptual framework has limited our understanding. Throughout, therefore, we suggest avian taxa for future studies, as well as additional questions and experimental approaches that would strengthen our understanding of the meaning of functional reference in avian alarm calls.

Semantic communication in birds: evidence from field research over the past two decades

“…Over the past three decades, researchers have explored functionally referential communication in many animal taxa including non-human primates (Zuberbu¨hler 2009;Manser 2013), ground-dwelling mammals (Townsend and Manser 2013), and birds (Gill and Bierema 2013). Similar to vervet monkeys (Struhsaker 1967;Seyfarth et al 1980a), these animals often produce different alarm calls for a variety of predators, and some of them can transmit many different types of information to receivers.…”

Common urban birds continue to perceive predator calls that are overlapped by road noise

“…Finally, one behavior; alarm calls, was not observed during any of our trials. This is somewhat expected since alarm calling generally functions as an aural warning upon visual detection of a predator (Gill and Bierema 2013). In our study, aural predator detection was easily made due to the playback of an identifying call.…”

Function of note strings in Japanese Tit alarm calls to the Common Cuckoo: a playback experiment

“…Predation is perhaps the most important threat to prey, as it may lead to death or mortal injury (Lima 2009). Therefore, predation pressure is one of the forces that may drive the evolution of alarm calls (Gill and Bierema 2013;Wheatcroft and Price 2015). The alarm calls of birds to different predators may vary depending on the context, such as predator type (aerial or terrestrial) and size or the predation threat level (Templeton et al 2005;Griesser 2008;Soard and Ritchison 2009;Suzuki 2012).…”