In king penguin colonies, several studies have shown that both parent-chick recognition and mate-pair recognition are achieved by acoustic signals. The call of king penguins consists of strong frequency modulations with added beats of varying amplitude induced by the two-voice generating process. Both the frequency modulation pattern and the two-voice system could play a role in the identification of the calling bird. We investigated the potential role of these features in individual discrimination. Experiments were conducted by playing back altered or reconstructed parental signals to the corresponding chick. The results proved that the king penguin performs a complex analysis of the call, using both frequency modulation and the two-voice system. Reversed or frequency-modulation-suppressed signals do not elicit any responses. Modifying the shape of the frequency modulation by 30 % also impairs the recognition process. Moreover, we have demonstrated for the first time that birds perform an analysis of the beat amplitude induced by the two-voice system to assess individual identity. These two features, which are well preserved during the propagation of the signal, seem to be a reliable strategy to ensure the accurate transmission of individual information in a noisy colonial environment.

REFERENCES

Aubin
T.
,
Jouventin
P.
(
1998
).
Cocktail-party effect in king penguin colonies.
Proc. R. Soc. Lond. B
265
,
1665
–.
Aubin
T.
,
Jouventin
P.
,
Hildebrand
C.
(
2000
).
Penguins usethe two voices system to recognize each other.
Proc. R. Soc. Lond. B
267
,
1081
–.
Dooling
R. J.
,
Brown
D. D.
,
Park
T. J.
,
Okanoya
K.
,
Soll
S. D.
(
1987
).
Perceptual organization of acoustic stimuli by budgerigars (Melopsitacus undulatus). I. Pure tones.
J. Comp. Psychol
101
,
139
–.
Jouventin
P.
,
Aubin
T.
,
Lengagne
T.
(
1999
).
Finding its parent in a king penguin colony: the acoustic system of individual recognition.
Anim. Behav
57
,
1175
–.
Lengagne
T.
,
Aubin
T.
,
Jouventin
P.
(
1999
).
Finding one's mate in a king penguin colony: efficiency of acoustic communication.
Behaviour
136
,
833
–.
Lengagne
T.
,
Aubin
T.
,
Jouventin
P.
,
Lauga
J.
(
1999
).
Acoustic communication in a king penguin's colony: importance of bird location within the colony and of the body position of the listener.
Polar Biol
21
,
262
–.
Lengagne
T.
,
Aubin
T.
,
Jouventin
P.
,
Lauga
J.
(
2000
).
672Perceptual salience of individually distinctive features in the calls of adult king penguins.
J. Acoust. Soc. Am
107
,
508
–.
Lengagne
T.
,
Aubin
T.
,
Lauga
J.
,
Jouventin
P.
(
1999
).
How do king penguins (Aptenodytes patagonicus) apply the mathematical theory of information to communicate in windy conditions?.
Proc. R. Soc. Lond. B
266
,
1623
–.
Weary
D. M.
(
1990
).
Categorization of song notes in great tits: which acoustic features are used and why?.
Anim. Behav
39
,
450
–.
White
S. J.
(
1971
).
Selective responsiveness by the Gannet (Sula bassana) to played-back calls.
Anim. Behav
19
,
125
–.
This content is only available via PDF.