Limits...
The vocal repertoire of the African Penguin (Spheniscus demersus): structure and function of calls.

Favaro L, Ozella L, Pessani D - PLoS ONE (2014)

Bottom Line: The African Penguin (Spheniscus demersus) is a highly social and vocal seabird.Moreover, we used a principal component analysis, followed by signal classification with a discriminant function analysis, for statistical validation of the vocalisation types.The results show that four basic vocalisations can be found in the vocal repertoire of adult African Penguin, namely a contact call emitted by isolated birds, an agonistic call used in aggressive interactions, an ecstatic display song uttered by single birds, and a mutual display song vocalised by pairs, at their nests.

View Article: PubMed Central - PubMed

Affiliation: Department of Life Sciences and Systems Biology, University of Turin, Turin, Italy.

ABSTRACT
The African Penguin (Spheniscus demersus) is a highly social and vocal seabird. However, currently available descriptions of the vocal repertoire of African Penguin are mostly limited to basic descriptions of calls. Here we provide, for the first time, a detailed description of the vocal behaviour of this species by collecting audio and video recordings from a large captive colony. We combine visual examinations of spectrograms with spectral and temporal acoustic analyses to determine vocal categories. Moreover, we used a principal component analysis, followed by signal classification with a discriminant function analysis, for statistical validation of the vocalisation types. In addition, we identified the behavioural contexts in which calls were uttered. The results show that four basic vocalisations can be found in the vocal repertoire of adult African Penguin, namely a contact call emitted by isolated birds, an agonistic call used in aggressive interactions, an ecstatic display song uttered by single birds, and a mutual display song vocalised by pairs, at their nests. Moreover, we identified two distinct vocalisations interpreted as begging calls by nesting chicks (begging peep) and unweaned juveniles (begging moan). Finally, we discussed the importance of specific acoustic parameters in classifying calls and the possible use of the source-filter theory of vocal production to study penguin vocalisations.

Show MeSH

Related in: MedlinePlus

Plot of the discriminant scores generated by the first two discriminant functions to classify vocalisations of the African Penguin.Black dots are the centroids of the vocal categories.
© Copyright Policy
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC4116197&req=5

pone-0103460-g002: Plot of the discriminant scores generated by the first two discriminant functions to classify vocalisations of the African Penguin.Black dots are the centroids of the vocal categories.

Mentions: The stepwise, cross-validated DFA correctly classified 90.5% of the vocal signals according to the predicted vocal categories that we assigned by inspection of spectrograms. The analysis generated four discriminant functions which revealed a highly significant difference between call types (Wilks' λ DF1/4 = 0.002, χ2 = 2446.73, p<0.001; Wilks' λ DF2/4 = 0.088, χ2 = 934.53, p<0.001; Wilks' DFλ 3/4 = 0.519, χ2 = 252.48, p<0.001; Wilks' λ DF4 = 0.985, χ2 = 5.93, p<0.05). The six vocal categories form distinctive clusters in the space defined by discriminant functions 1 and 2 (Figure 2). The percentage of correct assignment of each signal to the predicted vocal category is presented in Table 4.


The vocal repertoire of the African Penguin (Spheniscus demersus): structure and function of calls.

Favaro L, Ozella L, Pessani D - PLoS ONE (2014)

Plot of the discriminant scores generated by the first two discriminant functions to classify vocalisations of the African Penguin.Black dots are the centroids of the vocal categories.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4116197&req=5

pone-0103460-g002: Plot of the discriminant scores generated by the first two discriminant functions to classify vocalisations of the African Penguin.Black dots are the centroids of the vocal categories.
Mentions: The stepwise, cross-validated DFA correctly classified 90.5% of the vocal signals according to the predicted vocal categories that we assigned by inspection of spectrograms. The analysis generated four discriminant functions which revealed a highly significant difference between call types (Wilks' λ DF1/4 = 0.002, χ2 = 2446.73, p<0.001; Wilks' λ DF2/4 = 0.088, χ2 = 934.53, p<0.001; Wilks' DFλ 3/4 = 0.519, χ2 = 252.48, p<0.001; Wilks' λ DF4 = 0.985, χ2 = 5.93, p<0.05). The six vocal categories form distinctive clusters in the space defined by discriminant functions 1 and 2 (Figure 2). The percentage of correct assignment of each signal to the predicted vocal category is presented in Table 4.

Bottom Line: The African Penguin (Spheniscus demersus) is a highly social and vocal seabird.Moreover, we used a principal component analysis, followed by signal classification with a discriminant function analysis, for statistical validation of the vocalisation types.The results show that four basic vocalisations can be found in the vocal repertoire of adult African Penguin, namely a contact call emitted by isolated birds, an agonistic call used in aggressive interactions, an ecstatic display song uttered by single birds, and a mutual display song vocalised by pairs, at their nests.

View Article: PubMed Central - PubMed

Affiliation: Department of Life Sciences and Systems Biology, University of Turin, Turin, Italy.

ABSTRACT
The African Penguin (Spheniscus demersus) is a highly social and vocal seabird. However, currently available descriptions of the vocal repertoire of African Penguin are mostly limited to basic descriptions of calls. Here we provide, for the first time, a detailed description of the vocal behaviour of this species by collecting audio and video recordings from a large captive colony. We combine visual examinations of spectrograms with spectral and temporal acoustic analyses to determine vocal categories. Moreover, we used a principal component analysis, followed by signal classification with a discriminant function analysis, for statistical validation of the vocalisation types. In addition, we identified the behavioural contexts in which calls were uttered. The results show that four basic vocalisations can be found in the vocal repertoire of adult African Penguin, namely a contact call emitted by isolated birds, an agonistic call used in aggressive interactions, an ecstatic display song uttered by single birds, and a mutual display song vocalised by pairs, at their nests. Moreover, we identified two distinct vocalisations interpreted as begging calls by nesting chicks (begging peep) and unweaned juveniles (begging moan). Finally, we discussed the importance of specific acoustic parameters in classifying calls and the possible use of the source-filter theory of vocal production to study penguin vocalisations.

Show MeSH
Related in: MedlinePlus