Sexual dimorphism in responses to unfamiliar intruders in the tamarin, Saguinus oedipus

Aspects of social structure in group-living species can be inferred by observing the responses of individuals to unfamiliar animals. This study examined the responses of mated pairs of cotton-top tamarins (Saguinus oedipus oedipus) to presentation of either unfamiliar conspecifics or members of a related tamarin species, the saddle-back tamarin (Saguinus fuscicollis fuscicollis). Male and female responses to intruders differed: resident males threatened, displayed piloerection, approached, and attacked intruders, especially males, while resident females showed increases in suprapubic scentmarking in the presence of intruders. Both males and females discriminated between the species of intruders, exhibiting more threats, scent-marking, piloerection, and approaches in the presence of conspecific intruders. There are pronounced sex differences in the signals and behaviour patterns that are elicited in an aggressive or territorial encounter with unfamiliar conspecifics in this monogamous primate.     

Social development during the first twenty weeks in the cotton-top tamarin (Saguinus o. oedipus)

Fourteen infant cotton-top tamarins from five captive family groups were studied during the first 20 weeks of life. We examined the roles of parents and of siblings of different ages as caregivers and as social companions for the infants, as well as the effects of group composition and group size on these roles. Parents and adult siblings played similar active roles in infant caregiving during the first few weeks after birth, with males showing a greater involvement than females. In groups without other offspring the two parents showed equal infant caregiving behaviour, whreas fathers carried more than mothers did in groups with offspring present. Although infants received more caregiving from males, they showed a preference for contact and proximity with their mothers. No sex differences were found in infant behaviour or in the direction of behaviour by caregivers toward infants. Twins showed greater amounts of both social and solitary play in weeks 15–20 than did singletons, and there was no effect of the number of older siblings on the amount of play shown by an infant.     

Variations in care for cottontop tamarin, Saguinus oedipus, infants as a function of parental experience and group size

We examined the effects of parental experience and group size on infant care and development. Ten cottontop tamarin families were followed across three consecutive births of offspring to examine differences in survival, quality of care, developmental maturation and physical development for infants in two experimental conditions: (1) in large groups with previous parenting experience and (2) in small groups with little or no parenting experience. Although we found no differences in infant mortality, parents treated infants differently between conditions. However, when we examined the cumulative care provided by parents and sibling helpers together across experimental conditions, there were no differences in the rates of retrieval or rejection of infants. Overall levels of infant transport and food transfers were similar between conditions, with fathers and sibling helpers contributing the bulk of care. Fathers in small groups carried infants and transferred food with infants much more than helpers but, as group size increased, helpers augmented this role. Infant development varied with the experience of the family both between conditions and within a family. The results indicate that infants receive similar levels of care regardless of group size and parenting experience, although the individual contributions of family members change with both factors. Parental experience with previous infants had effects on early infant development, but only for the first sets of infants. Copyright 2002 The Association for the Study of Animal Behaviour. Published by Elsevier Science Ltd. All rights reserved.     

Problem solving, inhibition and domain-specific experience: experiments on cottontop tamarins, Saguinus oedipus

We present the results of experiments on cottontop tamarins designed to explore the relationship between problem solving, inhibitory control and domain-specific experience. The colony was divided into two groups: tool-experienced (TE) and tool-inexperienced (TI). The TE group had previously participated in a series of tool-use experiments and revealed that, when selecting a tool, they used featurally relevant dimensions (e.g. shape, material, orientation) over featurally irrelevant dimensions (e.g. colour). The TI group, although experienced in other laboratory-based experiments, had never been tested on tool or other object manipulation problems. In Phase 1, involving three conditions, all subjects were tested on a series of means-end problems involving the use of a cloth to access a piece of food. Although the correct choice always involved picking the supporting cloth, we also built in an association between the correct cloth and its colour. Once the subjects reached criterion, we reversed the association between the cloth colour and the food reward in Phase 2. If the subjects solved the problems in Phase 1 by attending to cloth colour, then in Phase 2 they should have difficulty, especially given prior findings on tamarins demonstrating that reversal learning is difficult. If the subjects solved Phase 1 by attending to the functionality of the problem (i.e. the physical/causal relationship between the cloth and food), then reversing the colours in Phase 2 should have no effect on the subjects' performances. Finally, if the subjects attended to both colour and functionality, then reversing the colours should cause some decrement in performance, but less so than in the case where colour alone dominates. In Phase 2, although both groups showed a decrement in performance, indicating problems with reversal learning, TE subjects significantly outperformed TI subjects. Furthermore, the pattern of performance for TE subjects suggested that they had solved the initial problem by attending to a combination of colour and functionality or functionality alone, while TI subjects had attended to colour alone. We conclude that for tamarins with experience as tool users, colour represents a less salient feature, even when it is systematically associated with a food reward. For inexperienced tamarins, however, colour is salient and reversal learning is difficult. Together, these findings highlight the importance of exploring the relationship between inhibitory control and domain-specific problem solving. Copyright 2002 The Association for the Study of Animal Behaviour. Published by Elsevier Science Ltd. All rights reserved.     

Perception of harmonics in the combination long call of cottontop tamarins, Saguinus oedipus

A number of nonhuman primates produce vocalizations with time-varying harmonic structure. Relatively little is known about whether such spectral information plays a role in call type classification. We address this problem by utilizing acoustic analyses and playback experiments on cottontop tamarins‘ combi nation long call, a species-typical vocalization with a characteristic harmonic structure. Specifically, we used habituation-discrimination experiments to test whether particular frequency components, as well as the relationship between components, have an effect on the perception and classification of long calls. In Condition 1, we show that tamarins classify natural and synthetic exemplars of the long call as perceptually similar, thereby allowing us to use synthetics to manipulate components of this signal precisely. In subsequent conditions, we tested the perceptual salience and discriminability of long calls in which we deleted (1) the second harmonic, (2) the fundamental frequency, or (3) all frequencies above the fundamental; we also examined the effects of frequency mistuning by shifting the second harmonic by 1000 Hz. Following habituation to unmanipulated long calls, tamarins did not respond (transferred habituation) to long calls with either a missing fundamental frequency or the second harmonic, but responded (discriminated) to long calls with the upper harmonics eliminated or with the second harmonic mistuned. These studies reveal the importance of harmonic structure in tamarin perception, and highlight the advantages of using synthetic signals for understanding how particular acoustic features drive perceptual classification in nonhuman primates. Copyright 2002 The Association for the Study of Animal Behaviour. Published by Elsevier Science Ltd. All rights reserved.     

A nonhuman primate's perception of object relations: experiments on cottontop tamarins, Saguinus oedipus

Objects in nature often have spatial and functional relationships with other objects. For example, fruit may be connected to tree branches, bushes sometimes function as landmarks for home, and stones are functionally associated with nuts when they are used to crack the nuts open. Although animals may use the spatial and functional relationships between specific objects, it is important for ethologists interested in cognitive mechanisms to ask whether animals understand the spatial relationship between objects in a more general and abstract way. In this experiment, we ask whether a small New World monkey, the cottontop tamarin, is capable of perceiving the abstract relational concept of ‘connectedness’. Using a traditional operant paradigm, subjects were required to press one button to images with connected objects, and another button to images with separated objects. In Phase 1 of the experiment, subjects received training with only one connected and one separated image. Following training, probe images were presented in which features such as colour, texture and shape were systematically manipulated to determine which features were more important in stimulus classification. Accuracies and reaction times of responses were recorded. On the basis of their performance, the tamarins appeared to recognize that changes in the colour or texture of two objects plays no functional role in determining whether such objects are connected or separated. In contrast, changes in the shape and distance between two objects does play an important functional role, and the tamarins appeared to be sensitive to such changes. In Phase 2, subjects received training with a larger set of images. After this training, classification accuracy remained significantly above chance with most probes, suggesting that the tamarins had acquired a more general connectedness concept. In Phase 3, novel images were presented. Classification accuracy was significantly above chance for many of the novel images. Overall, results suggest that tamarins perceive spatial relationships between stimuli to some extent and can classify images based in part on their spatial relationship. Other recent experiments have shown that cottontop tamarins respond to spatial relationships even better than in the current experiment when they have to act directly on the objects. The difference between these results suggests that tamarins perceive the spatial relationships between objects more readily in the context of an ecologically valid problem.     

Ontogeny of tool use in cottontop tamarins, Saguinus oedipus: innate recognition of functionally relevant features

Adult cottontop tamarins are sensitive to the functionally relevant and irrelevant features of objects used as tools to gain access to food. We conducted four experiments designed to assess whether infant cottontop tamarins show comparable sensitivities to functionally relevant and irrelevant features. All subjects were reared in a species-typical social environment, but prior to the present studies had never participated in any experiments, and had no access to tools or other freely moving, manipulable objects with the exception of food. Despite their lack of experience, the pattern of object choice by infants precisely mirrored those obtained with adults. Specifically, having learned to use a hard blue cane to retrieve food (experiment 1), infant tamarins immediately generalized to other objects (experiments 2-4), recognizing that changes in colour and texture play no role in an object's functionality as a tool, whereas changes in size and shape do. These data suggest that for cottontop tamarins, a species that does not naturally use tools, and infrequently manipulates objects, that the capacity to distinguish between functionally relevant and irrelevant features develops in the absence of domain-specific experience.Copyright 2002 The Association for the Study of Animal Behaviour. Published by Elsevier Science Ltd. All rights reserved .     

Scent-marking in free-ranging coyotes, Canis latrans

From November 1977 to March 1978 we recorded the scent-marking behaviour of free-ranging coyotes in southern Québec. Fourteen animals were marked by foot-pad ablation, which made it possible to recognize individuals' tracks in the snow and therefore to relate scent-marking with social organization. We observed 949 scent-marks. The identity of the animals was known for 50% of the tracking distances. Animals living in territorial groups (pairs and pairs with juveniles) marked more than twice as much as solitary non-territorial individuals. In addition the former used stronger forms of marking significantly more often than the latter.     

Scent-marking behaviour in response to conspecific odours by the rat, Rattus norvegicus

The scent-marking behaviour of male and female rats in response to conspecific odours was investigated in two experiments. The results of the first experiment indicated that exposure to conspecific odours generally led to an increase in marking rates. However, no sex differences were found, and large differences in marking responses according to the sex of the odour donor were only found for dioestrous females. These results do not suggest that the primary function of scent-marking in this species is sexual. In the second experiment, odour sources differed not only in the sex of the donor, but also in their relative familiarity to the animal being tested. This experiment showed that males marked more in response to odours from familiar (non-related) females. Females did not differ significantly on measures of marking but did display greater interest in odours from unfamiliar males. The results are discussed in relation to possible functions of marking in this species.     

Sex differences in the development of the thyroid gland in human prenatal ontogeny

A comparative study of the thyroid gland development in the human male and female embryos and prefoetuses was carried out. The development of incretory part of the testicles was shown to occur earlier than the differentiation of follicles in the thyroid gland and the appearance of colloid in it. Sexual differences were noted in the appearance of follicles, connective tissue, nerve fibres in the thyroid gland (earlier in the male foetuses). The processes of organ differentiation in the male foetuses were more active than in the female ones during the whole prenatal period of development. A suggestion is put forward that the sexual hormones of embryonic testicles influence the thyroid gland differentiation.     

Scent-marking in the grey short-tailed opossum (Monodelphis domestica)

The characteristics and social determinants of scent-marking behaviour were studied in a laboratory colony of grey short-tailed opossums (Monodelphis domestica), a small Brazilian didelphid. Scent-marking was sexually dimorphic, occurring more frequently and displayed at higher levels in males. Sexually immature males did not scent-mark; males just past the age of puberty (5 months) marked at low levels; and older males marked at high levels using the head, flank and chest. Male M. domestica preferentially scent-marked objects and areas previously marked by other males. Females showed interest in the scent-marks of males. We discuss similarities in scent-marking behaviour between this marsupial species and commonly studied eutherian species, and the possible functional significance of scent-marking in M. domestica.     

Sex differences in begging vocalizations of nestling barn swallows, Hirundo rustica

Parents of sexually reproducing species should adjust their investment in production of sons and daughters in relation to the relative costs and reproductive value of offspring of either sex. Sex allocation mediated by differential allocation of care such as food provisioning, however, requires that parents can identify offspring sex. We analysed sex differences in offspring begging calls that may serve as a cue for parents to discriminate between sons and daughters. A combination of three sonagraphic variables of begging calls of nestling barn swallows allowed us to classify them according to sex at day 16, but not at day 12 after hatching, suggesting that sex differences in begging calls arise during the nestling period as the time of fledging approaches. Hence, parents may be able to discriminate between sons and daughters by auditory cues, which would enable differential allocation of food between offspring during the late nestling and early fledging stages. Copyright 2003 The Association for the Study of Animal Behaviour. Published by Elsevier Ltd. All rights reserved.      

Sex differences in the lipolytic activity of Galleria mellonella fat body

The sexual differences in the intensity of production and release of free fatty acids (FFA) as well as the differences in the absolute amount of FFA produced and released from the fat body are most conspicuous at the sixth day after the larval-pupal ecdysis. Furthermore, it is demonstrated that a significant difference exists in the lipolytic activity of the fat body between the two sexes.     

Scent-marking with the subcaudal gland by the European badger, Meles meles L.

European badgers, Meles meles, possess a large subcaudal gland which is used for scent-marking the territory and other members of the clan. It was shown experimentally that a badger can distinguish secretions from different individuals. Dominant males scent-mark most, and lactating females more than other females. Scent-marks are distributed along the border of the territory, on bedding materials and around the sett, and on all members of the clan, especially females and cubs. The data support, in many details, the hypothesis that scent-making in badgers serves to establish an asymmetry of contest during encounters with intruders.     

Sex differences of functional lateralization in the perception of verbal and emotional information in ontogeny

Experimental data show certain differences between men and women in perception of verbal and emotional information. They are revealed in the ability of correct perception of definite kind of information, in the degree of brain functional asymmetry in perception of the given information, in prevalence of domination type. The character of sex differences in functional asymmetry changes little with the age; quantitative correlations of the coefficient of asymmetry diminish with the age.     

Scent-marking behaviour in free-ranging golden-faced saki monkeys, Pithecia pithecia chrysocephala: sex differences and context

Scent-marking behaviour of golden-faced saki monkey, Pithecia pithecia chrysocephala , was observed intermittently between 1987 and 1990 for a family group in a Central Amazonian forest fragment. Of 95 scent-marking events (during 275.5 hours of observation), throat-and-chest rubbing accounted for all except one anogenital rubbing. Nine of the throat-and-chest markings also involved touching groin with hands and eight markings (including the anogenital), urinating on the marked branch. Marking behaviour is strongly sex related, with the adult male making 88.4% of the markings. Scent-marking frequency by the adult male increased during breeding periods. Scent-marking behaviour seems related to courtship, and possibly stimulates sexual behaviour. All regularly marked spots consisted of horizontal branches on commonly travelled routes. Eleven occurred in feeding trees and lianas, but none in sleeping trees. Scent-marking behaviour in the monkeys studied here was not related to intergroup encounters and probably did not have a territorial function, although it may do so where different groups interact.