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Behaviour 142, 1
(Abstracts below)
Bond, AB & J Diamond (2005) Geographic and ontogenetic variation in the
contact calls of the kea (Nestor notabilis). Behaviour 142: 1-20.
Guerra, PA & AC Mason (2005) Male competition and aggregative behaviour are
mediated by acoustic cues within a temporally unstructured aggregation.
Behaviour 71-90.
Cirillo, J & D Todt (2005) Perception and judgement of whispered
vocalisations. Behaviour 142: 113-129.
Behaviour 142, 2
Collins, KT, TL Rogers, JM Terhune, PD Mcgreevy & KE Harcourt (2005)
Individual variation of in-air female 'pup contact' calls in Weddell seals,
Leptonychotes weddellii. Behaviour 142: 167-189.
Vettin, J & D Todt (2005) Human laughter, social play, and play
vocalizations of non-human primates: an evolutionary approach. Behaviour
142: 217-240.
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Bond, AB & J Diamond (2005) Geographic and ontogenetic variation in the
contact calls of the kea (Nestor notabilis). Behaviour 142: 1-20.
Regional and ontogenetic variation in the contact calls of the kea ( Nestor
notabilis), an omnivorous and socially complex New Zealand parrot, were
examined throughout the range of the species. We recorded samples of kee-ah
contact calls from sixteen resident adults and eleven juveniles and
demonstrated significant differences between age classes in the acoustic
form of the vocalization. Canonical correlation analysis revealed a
gradient in the form of the kee-ah call in both adults and juveniles along
and across the escarpment of the Southern Alps, the primary longitudinal
mountain range on the South Island of New Zealand. Although the juvenile
call varies geographically along the same axes as the adult version, the
aspects of the call that vary geographically are strikingly different,
suggesting that the variation results from independent processes of vocal
learning in the two age classes. A similar analysis of squeal
vocalizations, which are only produced by juveniles, fo!
und even greater levels of geographic variation. We suggest that the
immediate social environment may serve as the primary factor shaping the
vocal patterns of both juveniles and adults, producing localized
homogeneity in call form within each age class.
Guerra, PA & AC Mason (2005) Male competition and aggregative behaviour
are mediated by acoustic cues within a temporally unstructured aggregation.
Behaviour 71-90.
We investigated the dynamics of temporally unstructured acoustic signalling
aggregations, where direct interactions among males appear to be absent.
The short-winged meadow katydid, Conocephalus brevipennis Scudder
(Orthoptera: Tettigoniidae), is a species whose males form dense, aphasic
singing aggregations. By studying both phonotactic responses and male
calling behaviour towards conspecific, heterospecific, and aggregate
signals (combined songs of many individuals), we examined how males might
respond to acoustic signals within such aggregations, and whether such
apparently unstructured groups do in fact possess spatial or temporal
structure. Phonotactic bioassays demonstrate that males and females are
attracted to conspecific and aggregate, but not heterospecific song. When
given a choice between individual conspecific and aggregate song, females
prefer conspecific song, whereas males preferred aggregate song, but only
if it was presented at a lower relative intensity th!
an the individual song. Response to aggregate song also depended on male
size—the largest males approached the broadcast speaker more closely than
smaller males. Experiments examining male calling behaviour show that they
respond differently to playback of conspecific song, as compared to
heterospecific and aggregate signals. For heterospecific and aggregate
song, males decrease their singing rate, but recover after playback ceases.
Playback of conspecific song resulted in a decrease in singing that
persisted after the end of playback when males were initially weak singers,
but little effect for males that were initially strong singers. Males also
varied the number of species-specific 'tick' elements they included in
songs. Weaker singers reduced the number of ticks per song in response to
playback. Stronger singers increased tick rates for conspecific and
heterospecific playback, but decreased during aggregate song playback. Our
results demonstrate that calling song, in !
addition to attracting females, may be used by males to facilitate agg
regation and mediate the segregation of large and small signallers. Males
also compete acoustically with one another by varying their overall singing
rate and the frequency of tick elements relative to competing signallers.
Cirillo, J & D Todt (2005) Perception and judgement of whispered
vocalisations. Behaviour 142: 113-129.
Whispering is regarded as a close-contact vocalisation which, in structural
terms, clearly differs from normal (phonated) speech. Here, we present the
first experimental evidence for specific functional differences that
additionally exist between these two forms of human vocal communication.
Such evidence was collected by an inquiry into the perception and also the
social judgement of whispered vocalisations. Subjects were young adults
(mainly students; N=202) who were exposed to auditory stimuli which, for
exclusion of verbal effects, were given in artificial vocal patterns only.
To test for possible social effects, our stimuli (whispered phrases or, for
control, phonated phrases) simulated exposures to three socially different
situations: 'monologues', 'dialogues', and 'dialogues including laughter'.
Evaluation of self-report data collected after each stimulation revealed
that only the whispered stimuli received significant numbers of socially
negative judgements or votes,!
that documented 'feelings of social segregation'. Such judgements were
most frequent after exposures to 'dialogues including laughter', but less
frequent after 'monologues'. Taken together our study suggests that
whispering is not just a mere close-contact vocalisation, but a vocal
expression with specific social side-effects. To explain these effects we
presume that whispering signals primarily a strong affiliation of its
users, and that such role may make other listeners feel to be excluded from
a whispered interaction.
Collins, KT, TL Rogers, JM Terhune, PD Mcgreevy & KE Harcourt (2005)
Individual variation of in-air female 'pup contact' calls in Weddell seals,
Leptonychotes weddellii. Behaviour 142: 167-189.
Vocal recognition may function as a critical factor in maintaining the
phocid mother-pup bond during lactation. For vocal recognition to function,
the caller must produce individually distinct calls that are recognised by
their intended recipient. Mother-pup vocal recognition has been studied
extensively in colonial otariids and appears to be characteristic of this
family. Although less numerous, empirical studies of phocid species have
revealed a range of recognition abilities. This study investigated whether
Weddell seal (Leptonychotes weddellii) females produce individually
distinct 'pup contact' calls that function during natural pair reunions.
Fifteen calls from each of nine females recorded in the Vestfold Hills,
Antarctica were analysed. One temporal, nine fundamental frequency and five
spectral characteristics were measured. Results of the cross-validated
Discriminant Function Analysis revealed that mothers produce individually
distinct calls with 56% of calls assign!
ed to the correct individual. The probability of achieving this level of
discrimination on novel data by chance alone is highly improbable. Analysis
of eight mother-pup reunions recorded near McMurdo Sound, Antarctica
further demonstrated that these 'pup contact' calls function during natural
pair reunions. Behavioural analysis also revealed that pups were chiefly
responsible for establishing and maintaining close contact throughout the
reunion process. Our study therefore demonstrates that Weddell seal females
produce calls with sufficient stereotypy to allow pups to identify them
during pair reunions, providing evidence of a functioning mother-pup vocal
recognition system.
Vettin, J & D Todt (2005) Human laughter, social play, and play
vocalizations of non-human primates: an evolutionary approach. Behaviour
142: 217-240.
It has been hypothesized that the evolutionary origin of human laughter
lies in the facial play signals of non-human primates. Recent studies
dealing with human laughter have stressed the importance of the acoustic
component of this nonverbal behaviour. In this study, we analysed the
occurrence and some acoustic parameters, such as interval durations and
fundamental frequency, of Barbary macaque and chimpanzee play vocalizations
and human laughter during tickling. Play vocalizations occurred most often
during play with close bodily contact, i.e. wrestling and tickling. In both
Barbary macaques and chimpanzees, they were serially organized and had a
high intra-bout variability in their acoustic parameters. These are
characteristic features of human laughter which are crucial for deciding
whether a given utterance will be classified as laughter in humans. Besides
intra-bout variability, there was substantial intraindividual variability
which was as high or higher than the inte!
rindividual variability in all three species. Interval durations of
Barbary macaque and chimpanzee play vocalizations and human laughter during
tickling lay in a similar range. These results provide further evidence for
the hypothesis that human laughter evolved from a play signal of non-human
primates and raise questions about the importance of and the relationship
between facial and vocal play signals in the evolution of human laughter.
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