Cristina Giacoma, Viviana Sorrentino, Clement Rabarivola and Marco Gamba
(2010). Sex Differences in the Song of Indri indri. Intern. J. Primatol., 30
Abstract: In some primate species, males and females within a social group
emit loud calls in a coordinated manner or chorus. Indri indri emits a very
conspicuous loud call that elicits the loud calls of neighboring groups.
Previous investigations have hypothesized that the main functions of the
indri chorus are related to territorial announcement, intergroup avoidance,
and group cohesion. We investigated sex differences in indri song. We
recorded and analysed songs given by 10 different groups over 160 d. Overall
singing duration did not vary between the sexes. However, males emitted
significantly fewer but longer notes. Adult males and females of each group
participated in the song with sex-specific repertoires. Females had a song
repertoire of 8 note types; males shared all of their 6 notes with females.
Apart from the initial roars, in all note types shared by both sexes, male
notes were significantly longer than female ones, whereas variations in
frequency parameters differed according to the note type. These findings
suggest that indri song may provide cues to conspecifics, such as group size
and sex composition, which could influence interactions between groups.
For reprints please contact Marco Gamba (email:
Brandon C. Wheeler (2010): Decrease in Alarm Call Response Among Tufted
Capuchins in Competitive Feeding Contexts: Possible Evidence for
Counterdeception. . J. Primatol., 30 (4), 665-675.
Abstract: Animal signals function to elicit behaviors in receivers that
ultimately benefit the signaler, while receivers should respond in a way
that maximizes their own fitness. However, the best response may be
difficult for receivers to determine when unreliable signaling is common.
?Deceptive? alarm calling is common among tufted capuchins (Cebus apella
nigritus) in competitive feeding contexts, and responding to these calls is
costly. Receivers should thus vary their responses based on whether a call
is likely to be reliable. If capuchins are indeed able to assess
reliability, I predicted that receivers will be less likely to respond to
alarms that are given during competitive feeding contexts than in
noncompetitive contexts, and, within feeding contexts, that individuals
inside or adjacent to a food patch will be less likely to respond to alarms
than those further from the resource. I tested these predictions in a group
of wild capuchins by observing the reactions of focal animals to alarm calls
in both noncompetitive contexts and experimental feeding contexts.
Antipredator escape reactions, but not vigilance reactions, occurred
significantly less often in competitive feeding contexts than in
noncompetitive contexts and individuals adjacent to food patches were more
likely to respond to alarm calls than were those inside or further from food
patches. Although not all predictions were fully supported, the findings
demonstrate that receivers vary their behavior in a way that minimizes the
costs associated with ?deceptive? alarms, but further research is needed to
determine whether or not this can be attributed to counterdeception.
For reprints please contact Brandon C. Wheeler (email:
Bruna Martins Bezerra, Antonio S. Souto and Gareth Jones (2010): Vocal
Repertoire of Golden-backed Uakaris (Cacajao melanocephalus): Call Structure
and Context. Intern. J. Primatol., 31 (5), 759-778.
Abstract: The study of vocal behavior can reveal important aspects of how
and why a species communicates in relation to ecological and social
challenges. We here focus on vocal communication in golden-backed uakaris
(Cacajao melanocephalus), diurnal, pitheciine monkeys that exhibit
fission-fusion social organization and typically inhabit dense forests that
limit the potential for visual communication. Moreover, the species spends
little time engaged in tactile or olfactory communication, e.g., social
grooming and scent marking, respectively. Hence, vocalizations may be very
important for the coordination of social organization in these monkeys. We
1) categorized golden-backed uakari vocalizations, 2) ascertained their
behavioral context, and 3) investigated whether golden-backed uakari calls
can encode information about the signaler. We observed the monkeys during 2
wet seasons in the flooded igapó forest of Jaú National Park, Brazil. We
showed that golden-backed uakaris have 9 call types in their vocal
repertoire, all distinguishable by ear and from analysis of spectrograms.
Some calls, e.g., play-specific calls, were used only in particular
behavioral contexts, and by individuals of specific age, whereas others were
emitted under a range of situations. The structure of the loud tchó call
varied among individuals, and according to behavioral context, i.e., whether
individuals were foraging/feeding, traveling, or performing agonistic
interactions. This knowledge of the species? vocal repertoire is valuable
for surveying the monkeys acoustically in habitats where visual surveys are
For reprints please contact Bruna m. Bezerra (email:
Dr. Sonja Amoser