Interspecific audience effects on the alarm-calling behaviour of a kleptoparasitic bird.
Audience effects are increasingly recognized as an important aspect of intraspecific communication. Yet despite the common occurrence of interspecific interactions and considerable evidence that individuals respond to the calls of heterospecifics, empirical evidence for interspecific audience effects on signalling behaviour is lacking. Here we present evidence of an interspecific audience effect on the alarm-calling behaviour of the kleptoparasitic fork-tailed drongo (Dicrurus adsimilis). When foraging solitarily, drongos regularly alarm at aerial predators, but rarely alarm at terrestrial predators. In contrast, when drongos are following terrestrially foraging pied babblers (Turdoides bicolor) for kleptoparasitic opportunities, they consistently give alarm calls to both aerial and terrestrial predators. This change occurs despite no difference in the amount of time that drongos spend foraging terrestrially. Babblers respond to drongo alarm calls by fleeing to cover, providing drongos with opportunities to steal babbler food items by occasionally giving false alarm calls. This provides an example of an interspecific audience effect on alarm-calling behaviour that may be explained by the benefits received from audience response.
Ridley
Amanda R
AR
Percy Fitzpatrick Institute, DST/NRF Centre of Excellence, University of Cape Town, Rondebosch, Cape Town 7701, Republic of South Africa. amanda.ridley@uct.ac.za
Child
Matthew F
MF
Bell
Matthew B V
MB
D000818:Animals; D046109:Passeriformes / Q000502:physiology*; D012919:Social Behavior; D014828:Vocalization, Animal
Am Nat. 2006 Dec;168(6):E180-204
17109314
Curr Biol. 2006 Sep 5;16(17):1700-4
16950106
Proc Biol Sci. 2004 Apr 7;271(1540):755-9
15209110
J Theor Biol. 1977 Aug 7;67(3):603-5
904334
Annu Rev Psychol. 2003;54:145-73
12359915