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Laughter is an ingroup display which, in humans, occurs in a large variety of forms. Especially its vocal features play a key role in social interaction, since they can trigger laughter on the basis of auditory perception, and so mediate the phenomenon of contagion (Provine and Yong, 1991, Ethology, 89, 115-12). Nevertheless, the acoustic features of laughter have received little attention by investigators in the past, as compared to its non-acoustic features. In our current study on laughter we are concentrating on both the dynamics of its signal parameters and its interactional role. Concurrently, we focus on comparative aspects. The results reported here refer to the sound patterns produced by humans who were tickled and others recorded from chimpanzees during playful encounters which included mutual tickling. In addition, we present data of vocalizations produced by Barbary macaques Macaca sylvanus engaged in playful wrestling (Todt et al., 1992, Primate Report, 32, 19-30). Beside some clear differences, we found a number of similarities among acoustic patterns uttered during such encounters. Differences concerned e.g. the relationship between vocalizations and facial displays: in the Barbary macaque, sound patterns were temporally segregated from the occurrence of a 'play face'. Whereas the latter predominantly preceded body contact of interactors, the vocalizations occurred after contact was established and wrestling became intensive. Congruencies concerned e.g. the rhythm, and specific variations of formant features. Our results contribute to hypotheses on relationships between laughter and playful ingroup behaviours. In addition they allow a novel discussion on laughter homologies as originated e.g. by R. Andrew (1963, Behaviour, 20, 1-109) and J. v. Hoof (1972, in R. Hinde, ed., Non-verbal Communication, Cambridge University Press), or continued by S. Preuschoft (1992, Ethology, 91, 220-236).

Individual recognition of infant vocalizations by the mother is described in several species. Beyond the information about the context (e.g. lost calls), the calls have to contain information about individual specificity, extracted by acoustic parameters. If these acoustic parameters underlie a trend within a calling sequence, it describes a part of the intra-individual variability. The aim of this study was to determine the temporal dynamic of those acoustic parameters which describe in the best way the individual differences in vocalization. In two captured groups of Japanese macaques Macaca fuscata vocalizations of infants (6 and 7 months old) were recorded in defined contexts. A compound call from the infant vocal repertoire, consisting of two acoustic elements, was selected to measure 18 parameters. These parameters were tested according to their ability to separate the recorded calls of nine infants. The procedure of a discriminance analysis was used. The maximal correct assignment was reached by using 9 out of 18 parameters. An increase in the number of parameters above 9 could not improve the result. The temporal development of these 9 parameters within a calling sequence was determined by trend analysis. It reveals an unrelated dynamic of the 9 parameters, e.g. the starting fundamental frequency was constant over time in all calling sequences of all animals, while other frequency points underlie trends. A relationship between the parameter dynamic and the detailed behavioural response is shown.

Organization inside a colony of social insects is based on complex communication media. At present acoustic communication is found to carry various meanings (alarming, reciprocal recognition, other behavioural effects) together with chemical and tactile ones. The five species studied were Ectatomma permagnum Forel, E. quadridens Fabn, E. ruidum Roger, E. tuberculatum Oliver, Pachycondyla apicalis Latreille. The Ectatomma genus, present with 12 species in the tropical forests of Central and South America, has never been studied previously in relation to acoustic emissions. Stridulations were only heard, in the four species considered in this paper, during artificial disturbance of individuals or of the whole colony; so the role of sound production during normal life is still uncertain. Pachycondyla apicalis, while belonging to Central American forests, is also occasionally present in cocoa and coffee plantations. Ultrasonic signals were acquired using a Bruel & Kjaer 2231 phonometer with a B&K 4135 transducer (frequency response up to 100 kHz). Signals were fed into an amplifier with anti-aliasing low-pass filter to be digitally recorded and analyzed on a Pc-based Digital Signal Processing Workstation. Sampling frequencies up to 200,000 s/s allowed the recording up to 87.5 kHz. The ants were picked up with a pincer and the microphone was kept at a distance of approx. 1 cm. All the recordings made under laboratory conditions revealed the emission of pulse trains with very clear pulses extending in frequency up to 75 kHz. The sounds recorded from the genus Ectatomma appeared homogeneous in their acoustic structure, They were typically emitted in long sequences and were made by pulse-trains consisting of two subunits (disyllabic chirps) characterized by pulses with opposite phase, produced by the alternate movement of the simple plectrum against the pars stridens. In Pachycondyla sounds we found sequences of monosyllabic chirps, made by a single train of pulses. Pictures and measurements on the stridulatory apparata were made with a Scanning Electron Microscope Cambridge S 250 TP.

The calls of Pipa carvalhoi were recorded with a hydrophone and analysed with a sound level meter, and the data compared with those measured in air. Three types of calls can be differentiated in males (females are not able to produce calls):

• the advertisement call which is composed of clicks followed by a series of rapid identical pulses; this series, called buzz by Weygoldt (1976), is named trill here;
•  the encounter call consisting of short trills, and
• a call which is very similar to the encounter call, but preceded occasionally by clicks. It is produced by males in response to amplexus.

The sound pressure level of trills reached 120 dB, that of clicks 90 dB. Corresponding data for the sound measured in air are 62 and 41 dB. Experiments with wall covers suppressing resections suggest that the high dB values measured in normal aquaria are unbiased. Calling activity is high at midnight and in the morning; it increases in the presence of receptive females. In a group, the dominant male calls; however, when a female becomes receptive, other males produce encounter calls.

The scarlet rosefinch Carpodacus erythrinus populates large areas of the Palearctic zone. Beginning more than 30 years ago, the species expanded from its population centre in Asia and Eastern Europe to Northern and Western Europe. New breeding populations were thereby established, not only in suitable environments on the Baltic coast, but also along the big rivers (Vistula, Warta, Odra) and in the Central European inland area (for example The Alps, Bohemian Forest and Ore Mountains). While the process of expansion is well documented, we have very little information about the origin of the founder birds. During the last 15 years, the songs of more than 800 individual scarlet rosefinches (the whole of the five subspecies) were recorded. The spectrographic analysis shows that two different song forms are used by the males:

• the so-called short song which consists of 4-6 notes and varies in pattern and arrangement of the notes between individuals;
• the so-called long song which contains at least 9 notes and has a more or less homogenous structure in the whole area of the recent distribution of the species.

An analysis of the different types of the short song shows an increase of variation from the final to the initial notes. The final note is used for the description of song types, which can be divided into sub-types using other notes. The basic structure of the short song is identical for all sub-species. While in the Siberian, Middle Asian and Caucasian breeding areas we found that the birds prefer only certain types of notes, in the small isolated Central European micro-populations dialect songs emerged. Dialect songs were probably established by founders of the local breeding population. During the stabilization of the micro-population and with the increase in the number of individuals, a uniformity of song type takes place. Each population is characterized by one dominant song type or dialect. It can be assumed that the dialect is a learned marker by a micro-population.

The poster shows vocalisations of four currassow species by sonagraphic analysis.  All sounds were recorded from caged birds in different behavioural situations in the Zoological Gardens of Berlin. The special meaning of the various vocal utterances given by curassows in the wild have not been completely investigated yet. This poster tries to illustrate the territory sounds of the great Crax rubra, razor-billed Crax mitu, northern helmeted Crax pauxi and nocturnal Notocrax urumutum curassows, and the vocalisations of the northern helmeted curassow at the beginning of the pair formation process.

The song of the little bunting from different parts of the species area was analysed. There was found to be a very high variability:

• Song bouts include 2 to 4 song types. Each song type consisted of phrases, which followed in stereotyped order.
• The duration of songs ranged between 1.0 and 2.8 sec.
• After 3 to 14 songs the birds switch to another song type. During the changing of song type only in a few cases could intermediate forms between two types be observed.
• Five song types could be found in the same matter in different individuals from different parts of the area.

It is concluded that the repertoire of the species is a pool of song types. The variability is based on the learning of the whole song type as a pattern.

Currently, there is a lively public discussion about the pros and cons of keeping dolphins in captivity, and a growing number of people demand the rehabilitation of these creatures. However, such an enterprise is difficult to achieve if one wants to do it in a biologically adequate manner. A few months ago we started to tackle this matter by studying a group of bottlenose dolphins (for details see Todt & Hultsch, 1995, Europ. Res. Cetaceans, 9). The Tursiops truncatus group is living in semi-free confinement adjacent to the Red Sea (site: Dolphin Reef/Eilat; size of site: > 10.000 m², depth: 18 m; size of group: 5 adults (2/3), 3 juveniles (2/1), 1 call). The site is separated from the open sea by a wide-mesh net only, and has been recently a gate to the sea is open for two hours per day. For a long time, however, and otherwise than expected, only one individual made use of the opportunity to swim out for an excursion, whereas the other ones repeatedly inspected the gate without passing through completely. In order to further investigate why the dolphins seemed to have problems with such physical barriers, we built a new enclosure and invited the animals to explore and also to use it by voluntarily passing a second experimental gate. Then, we recorded how the dolphins coped with this setting (recording equipment linked to videocameras and hydrophones). Behavioural data were evaluated in terms of correlations between the vocalizations and stress-causing events, such as problems preceding or following any trial to pass the gate (for details of parametric analysis see Janik, Dehnhardt, Todt, 1994, Behav. Ecol. Sociobiol., 23, 15-21, or Hammerschmidt & Todt, 1995, Behaviour, 132, 381-399). Our results confirmed that bottlenose dolphins may indeed have problems in passing physical barriers. But they showed also how these animals finally solve such problems. In addition, the study documented a variety of vocalizations which were correlated to the quality of the particular test episodes or the animals' intrinsic state, respectively.

The song of the chaffinch Fringilla coelebs is one of the best studied song patterns of any bird species. The geographic variation of song structure has received special attention and was investigated in detail in several parts of western Europe, especially England, Scotland and Germany. As far as we know, a thorough large-scale sonagraphic analysis of geographic variation in central and eastern Europe is still missing. Here we report aspects of song type distribution, of repertoire sizes, and of the occurrence of the widespread terminal song element kit in several chaffinch populations in Poland. During the breeding season 1994 we recorded 84 male chaffinches in five areas (average distance between areas: 330 km). We found a total of 57 song types, of which up to 21 were sung in the individual study areas. The basic song structure (several trill-like parts followed by a complex end phrase), duration and the overall distribution of song types (song type sharing between areas) matched those described for western Europe, but there were differences in the frequency distribution of song types within a population and to some extent in repertoire sizes. Specific results:

1) There was a negative correlation between the number of song types shared and the distance between two areas.

2) In each of the study areas, some song types were more frequent than others. However, even the most common song type within any study site was sung by not more than 20 to 33% of all males of that area, the lowest values reported so far for chaffinches. Such an unusual frequency distribution of song types may be due to factors like pronounced changes in song structure during song learning and/or a high exchange rate (immigration and emigration) of males with other areas. This, however, still needs to be investigated.

3) Males had a mean repertoire of 2.0 song types, which is significantly smaller than most of the repertoires reported for England, Scotland and Germany. There was a pronounced similarity between the study areas in the mean repertoire size of males (an average of 2.0 song types per male

in four areas and 1.9 song types in the fifth area).

4) The characteristic terminal song element kit was sung in all study areas. However, the proportion of males with kit differed significantly between the sites (8 to 100%), with highest values in the northwestern populations.

We plan to investigate the songs of chaffinch populations in central and eastern Poland to determine whether there is a geographic gradient in the kit frequency (from north to south?) or whether it varies in an irregular pattern.

As with many other songbirds, the singing behaviour of adult nightingales Luscinia megarhynchos is distinguished by a temporally very regular alternation of songs (strophes) and silent inter-song intervals (pauses). These pauses are essential for the vocal interaction among conspecifics, as they allow them to listen to and respond .to the songs of other birds (Hultsch & Todt, 1982, Beh. Ecol. Sociobiol., 11). In the past, many studies have dealt with how song patterns are acquired and developed. In contrast, the ontogenetic development of the time structure of singing has been a neglected issue. In nightingales, the most conspicuous change during this process occurs towards the end of the first year of birds, when they gradually switch from juvenile continuous singing to the adult discontinuous singing style. Our study examines the characteristics of this transition and the rules underlying its temporal patterning! We investigated the singing of seven male birds who had been trained as fledglings with different song strings (duration of intervals between successive master-song types: 4s). Six of these birds were kept in auditory isolation after the tutoring period. To check for influences of social experience on song development, one male was housed in auditory contact with other nightingales. A further male had no exposure to any song (acoustic isolate). In all tutored birds (i.e. including the 'contact' male), the transition from continuous to discontinuous singing started at week 45 posthatching (SD: 3 days). It lasted between 18 and 37 days (early April to early May). In the acoustic isolate, the beginning of temporal crystallisation was delayed (week 47 p.h.), but it took him only 13 days to develop the adult singing style. To further characterise the transition process, we measured for each male the duration of app. 100 consecutive inter-song intervals (0.85s-12s), starting with the first singing bout in the morning of 10 days during the period mentioned above. This analysis revealed that the transition process can be divided into two distinct phases. The first phase is characterised by a gradual increase of the pause durations from 1.7s to 2.8s (medians). This increase succeeded within max. 7 days. Interestingly it was followed by a marked decrease in pause durations, during which 5 birds even regressed to continuous singing again. In the second phase, the duration of inter-song pauses increased again and progressed to the adult time structure within 20.3 days (SD: 4.8 days). Inter-song pause duration ranged from 2.4s to 4.5s (medians) then. Temporal development in both the 'contact' male and the isolate male was consistent with these characteristics, i.e. they did not differ significantly in any aspect from the other birds. We conclude from these findings that the ontogeny of the adult time structure of singing follows a developmental program in which intrinsic, age related variables play an important role. In particular, the evidence from the onset and course of the transition from continuous to discontinuous singing, which was very consistent among the tutored birds, supports the assumption of an age trajectory in development. This trajectory, however, may not be independent from feedback from the individual's performance skill, as suggested by the delay in transition onset in the acoustic isolate. Further experiments are needed to substantiate this finding. Also, the ontogenetic regression in pause durations (end of phase 1) has to be examined for covariation with other variables in the singing behaviour during that period. Concomitant with temporal regression could be, for instance, a decrease in singing activity (Kopp, 1992, Ber., 125. Jahrestagung DO-G), or structural 'quality' of the performance. Elucidating the interaction or independence of such variables will further our understanding of processes and mechanisms involved in behavioural development.