"MZE-RO0719"
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The effects of social separation, including vocalization, have been studied for a very long time in non-human primates under laboratory conditions. As part of the long-term research on the vocal behaviour of Nomascus gibbons in zoos, this study provides the first record of calls of the southern yellow-cheeked gibbon (Nomascus gabriellae) in response to involuntary separation. Our study revealed that calls were also emitted by an infant (aged 1 year 8 months), and that the acoustic structure of the infant's calls was similar to that of older individuals' calls. Separation-induced calls seem to have a shorter developmental convergence than vocalizations with a stable pattern (which are specific for species and sex). The acoustic structure of the calls reported here comprised simple syllables, and differed from the sex- and species-specific vocal patterns of this species. Our findings demonstrate a novel paradigm in this genus, and provide evidence of the ability of gibbons to express distress when socially separated.
- MeSH
- Hylobatidae fyziologie MeSH
- sociální chování * MeSH
- věkové faktory MeSH
- vokalizace zvířat * MeSH
- zvířata v ZOO fyziologie MeSH
- zvířata MeSH
- Check Tag
- mužské pohlaví MeSH
- ženské pohlaví MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
Overmarking remains an unstudied topic in juvenile mammals. We have previously documented a very high rate of overmarking by foals in four captive African equid species: mountain zebra (Equus zebra), plains zebra (Equus quagga), Grévy's zebra (Equus grevyi), and African wild ass (Equus africanus). African equids vary interspecifically in their social organisation. Since differences in social organisation affect many mammalian behaviours, in this study we investigated interspecific differences in overmarking behaviour of foals, analysing only cases where elimination of any other individual was explored by a foal. We hypothesised that the pattern of overmarking by foals should reflect either differences in social organisation of the species or phylogenetic relations among them. We found that in all species very young foals explored mostly maternal eliminations, and this preference declined with increasing age of the foal and reflected the social organisation of the species; the highest overmarking rate was in species with high intragroup aggression (mountain zebra) and lowest in species with low intragroup aggression and which form crèches (African wild ass). Similarly, the rate of overmarking of the mother, as opposed to other herdmates, was associated with social organisation of the respective species. Thus, we found interspecific differences in overmarking by foals, which were associated with variability in social organisation. Since we also revealed differences between African wild ass and zebra behaviour in early stages of ontogeny, we cannot refute the effect of phylogeny on overmarking behaviour. Additionally, our results supported the identity sharing hypothesis as an explanation of overmarking.
To elucidate the role of domestication, we used the impossible task paradigm to test Czechoslovakian Wolfdogs with a known proportion of 'wolfblood' in their DNA and, as a control group for our subjects, we used German shepherd dogs. We hypothesized that the difference between wolves and domestic dogs is based on genetics and modified by obedience; if so, the looking back performance of the subject should be linked to its proportion of wolf-genes. To prove that, we observed 73 Czechoslovakian Wolfdogs, and 27 German shepherd dogs, and analysed their human-directed gazing behaviour during our test. Our apparatus consisted of a glass container placed upside down over a small amount of food. The test proceeded with three solvable trials, in which the subject could obtain the food by manipulating the container, followed by an unsolvable one in which the container was fixed onto the board. Our results suggest that there is no significant correlation between the probability of looking back in Czechoslovakian Wolfdogs and their proportion of 'wolf blood'. However, the probability of looking back was higher in German Shepherd dogs than in Czechoslovakian Wolfdogs (odds ratio = 9.1). German Shepherd dogs showed not only a higher frequency of looking back, but also the duration of their looks was longer.
Overmarking occurs when one individual places its scent mark directly on top of the scent mark of another individual. Although it is almost ubiquitous among terrestrial mammals, we know little about the function of overmarking. In addition, almost all studies on mammalian overmarking behaviour dealt with adult individuals. Reports on this behaviour in juveniles are extremely rare, yet may elucidate the function of this behaviour. We tested four mutually non-exclusive hypotheses which might explain this behaviour in juveniles: (1) conceal the individual's scent identity, (2) announcement of association with other group members, especially the mother-i.e., sharing identity with the mother, (3) to prevent the next conception of the mother, i.e., parent-offspring conflict, and (4) an early expression of male sexual behaviour. We observed 43 foals (out of 108 individuals) from all African equid species (Equus africanus, E. grevyi, E. quagga, E. zebra) in five zoos. In total, we recorded 3340 eliminations; 260 of these events were overmarked by 38 individual foals representing all species. This represents one of the highest rates of overmarking ever recorded by mammalian juveniles. Foals of all species except African wild ass overmarked the mother more often than another herdmate: with male foals overmarked at a higher rate than female foals. Mothers preferred to overmark foals, but not exclusively their own foal. Our results provide support for the hypotheses that overmarking serves to share identity between foal and mother, and that it is an early expression of male sexual behaviour.
- MeSH
- feromony * MeSH
- koně * MeSH
- matky MeSH
- odoranty MeSH
- zvířata MeSH
- Check Tag
- mužské pohlaví MeSH
- ženské pohlaví MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
