: Alarm calls

Thank you to Richard for correctly pointing out that “pinna” is singular and “pinnae” is plural. It appears that I and the authors of the scientific paper used “pinna” at times when “pinnae” would have been more appropriate. Kind regards, Stephen Stephen Ambrose Ryde NSW —–Original Message—– From: birding-aus-bounces@lists.vicnet.net.au [mailto:birding-aus-bounces@lists.vicnet.net.au] On Behalf Of Stephen Ambrose Sent: Tuesday, 17 December 2013 10:19 AM To: ‘Paul McDonald’; ‘Shirley Cook’ Cc: ‘Birding Aus’ Subject: Re: [Birding-Aus] : Alarm calls As an aside, in the 1970s in Western Australia, Ian Rooke (Uni of Western Australia) and Terry Knight (CSIRO) examined alarm calls of New Holland, White-plumed and White-naped Honeyeaters. They found that specialised ear-feathers were probably acting as pinna, assisting the honeyeaters to better perceive the directions, locations and intensity of sounds. The intensity and volume of the alarm call of individual honeyeaters are higher the closer the predator is to them. Therefore, if an aerial predator flies over a flock of honeyeaters, individuals can determine how close the predator is to them and the direction it is flying over the flock by listening to the intensity and volume of alarm calls of conspecifics in their immediate area. Stephen Ambrose Ryde NSW Reference: Rooke, I.J. & Knight, T.A. (1977). Alarm calls of honeyeaters with reference to locating sources of sound. Emu 77: 193-198. Abstract The alarm calls that are given in response to a flying hawk by the New Holland Honeyeater Phylidonyris novaehollandiae, the White-plumed Honeyeater Lichenostomus penicillatus and the White-naped Honeyeater Melithreptus lunatus are described. Animals locate sources of sound by comparing differences in intensity, phase and timing cues of the incident sound at each ear. These processes are explained and previous explanation is criticized. Some animals create more directional cues from incident sound with pinna. The structure of the alarm calls of honeyeaters makes them easy to locate and some honeyeaters possess specialized ear-feathers that may function as pinna. The function of the alarm calls is discussed with reference to survival value.