J. A. R. A. M. van Hooff

Chronic stress in dogs subjected to social and spatial restriction. II. Hormonal and immunological responses.

Two groups of beagles, accustomed to spacious group housing, were subjected to social and spatial restriction and studied for manifestations of chronic stress with a time interval of 7 weeks between the groups. The change from outside group housing (the control period) to individual housing in small indoor kennels resulted in sustained decreases in urinary adrenaline/creatinine and noradrenaline/creatinine ratios for the total group. Urinary dopamine/creatinine and noradrenaline/adrenaline ratios were statistically unaffected. Socially and spatially restricted dogs that had experienced pleasant weather during the control period showed (a) increased salivary and urinary cortisol concentrations, (b) a diminished responsiveness of the pituitary-adrenal axis to a sudden sound blast or exogenous CRH, (c) intact plasma ACTH and cortisol suppressions after dexamethasone administration, and (d) increased concanavalin A induced lymphocyte proliferations. When social and spatial restriction was preceded by a control period during which the weather was bad, these physiological responses were either augmented (lymphocyte proliferation), or offset (salivary and urinary cortisol), or directed oppositely (CRH-induced ACTH and cortisol responses). Together with the previously presented behavioral observations, these data suggest that bad weather conditions during spacious outdoor group housing induced early stress that attenuated the negative appraisal of the subsequent period of social and spatial restriction. In comparison to male dogs, bitches showed increased HPA responses to a sound blast or exogenous CRH. Their increased attenuations of the ACTH and cortisol responses to CRH after 5 weeks of restricted housing indicates that bitches are not only more susceptible to acute stress, but also to chronic housing stress. It is concluded that the quality of circumstances preceding a period of affected well-being determines the magnitude and even the direction of the behavioral and physiological stress responses. Basal salivary and urinary cortisol measurements are useful for the assessment of chronic stress, and of poor welfare in dogs. The use of urinary catecholamine, peripheral leucocyte, and lymphocyte proliferation measures requires further investigation.

Ecological constraints on the grouping of wild orang-utans (Pongo pygmaeus) in the Gunung Leuser National Park, Sumatra, Indonesia

The orang-utan (Pongo pygmaeus)is an interesting subject on which to base an evaluation of the costs and benefits of social life in apes, since grouping in this heavy, arboreal frugivore is facultative. In the Ketambe area of Sumatra, Indonesia, the food sources of wild orang-utans display a clear seasonality. The two main food types— figs and other, nonfig, fruits— fulfill different functions. The huge fig trees meet the high caloric requirements of the ape and are therefore visited regularly throughout the year. Nonfig fruits are an additional food source but become a really important alternative when figs are in short supply. Since fig trees are relatively rare, it is only in the nonfig fruiting season that food is relatively abundant. Two types of orang-utan groupings could be distinguished. During lean periods, groups formed in the few productive fig trees available can be explained as forced aggregations taking place in spite of centrifugal forces caused by competition. Only when a temporary surfeit of food slackens these centrifugal forces (i.e., during the fruit season) does the tendency to form spontaneous social groups (the second type of grouping) reveal itself. It is suggested that the development of social skills is an important aspect of grouping in adolescent orang-utans. For the adult male, safeguarding his reproductive success by protecting females against sexually aggressive subadult males is probably the only reason for being in groups.

The vocal expression of feeding motivation and frustration in the domestic laying hen, Gallus gallus domesticus

Thwarting of feeding behaviour in the laying hen results in an increase in stereotyped pacing, displacement preening, and the gakel-call. These behaviours therefore reflect the frustration arousal caused by the thwarting of feeding behaviour. This raises the question whether the level of frustration also varies with the intensity of the motivation to perform the thwarted behaviour. This study investigated the relationship between the intensity of the motivation and level of frustration on the one hand and the gakel-call on the other hand. In Experiment 1, the strength of the motivation to feed was varied by thwarting hens in their feeding behaviour in an operant procedure after different durations of food deprivation (0, 8, 23 and 47 h). Trend analysis showed that with increasing hunger state, an increasing number of gakel-calls was given. No effect of treatments on temporal characteristics of the gakel-call was found. In Experiment 2, the level of frustration was varied by reducing or increasing the duration of access to food for food-deprived hens compared to the duration of access during training. It was assumed that a shorter duration of access to food compared to training would elicit frustration, which in turn would affect the performance of behaviours indicative of thwarting. However, we found neither a relation between the number of gakel-calls nor the temporal features of the gakel-call and the duration of access to food. Possibly, the differences between treatments were not large enough to induce differences in frustration level. Also, other factors that might have influenced the motivation are discussed.

Aging, Dominance History, and Social Behavior in Java-Monkeys (Macaca fascicularis)

The aim of this study was to investigate the influence of the dominance history of socially housed Java-monkeys on the aging process. In monkeys, social subordinance is generally associated with elevated levels of cortisol, which, in turn, have been suggested to influence cognitive decline. As cognitive skills are necessary for successful social life, we investigated the effect of old age in relation to the dominance history of the animals on their social behavior by comparing old females with their younger daughters. Old age, especially in combination with a history of low rank, led to a withdrawal from social interactions with unfamiliar animals and to a decrease in amounts of aggression received. Still, however, old animals showed an increase in behaviors associated with arousal. A reduced ability to deal with complex social interactions, caused by a decline in information processing abilities, is suggested as an explanation for these results.

Life-Phase Related Changes in Male Loud Call Characteristics and Testosterone Levels in Wild Thomas Langurs

Males in many primate species give loud calls. Lifetime changes in loud calls may be due to either age or social changes. We examined loud call characteristics, loud call production and levels of fecal testosterone among 4 life-phases of male Thomas langurs (Presbytis thomasi): all-male band (AMB), early, middle, and late life-phase in mixed-sex groups. Discriminant analyses showed that a high percentage of loud calls could be assigned correctly to the proper life-phase. The most significant change in loud call characteristics is an increase in tonal units and duration from the AMB to the early life-phase, accompanied by a decrease in non-tonal units. Since adult AMB males have a similar age to that of early life-phase males, we suggest that social rather than age-related changes underlie the loud call differences between AMB males and early life-phase males. This could also be related to the increase in testosterone levels from the AMB to the early life-phase. In addition, we postulate that females may use loud call characteristics as a cue to choose between young and old males once they decided to leave their current male, and possibly also as a cue to decide to leave their current male as he enters his late life-phase.

A case of the adoption of an infant chimpanzee by a suckling foster chimpanzee

Chimpanzees in captivity have grown up in a rather unnatural social environment and there frequently are problems when they have to nurse their own offspring. It is most remarkable that a chimpanzee mother in a captive colony, who had lost her child almost immediately after birth, adopted without problems a five-week-old infant, which had been reared by humans from the day of its birth. Successful adoption has not been reported for feral chimpanzees; similar cases in captivity are not known.

Differences in cortisol response affect the distinction of observed reactive and proactive aggression in children with aggressive behaviour disorders

Summary.Various researchers distinguished two categories of aggressive behaviour, namely reactive and proactive aggression. Reactive aggression is an aggressive response to a perceived threat or provocation, whereas proactive aggression is behaviour that anticipates a reward. In the present study, including both a sample of disruptive behaviour disordered (DBD) and normal control (NC) children, we observed reactive and proactive aggressive behaviour during an experimental dyadic play session. DBD children showed more observed reactive and proactive aggression. Subsequently, we investigated whether the observed measures correlated with parent-rated measures of reactive and proactive aggression in. We distinguished in both NC and DBD children a subgroup showing a rise in cortisol level, i.e. responders, and a subgroup who did not show a rise in cortisol, i.e. non-responders. Results suggest that differences in the cortisol response affects the correspondence between observed and parent-rated reactive and proactive aggression since only DBD non-responders showed the expected correlations.

Behavioral aspects of puberty in group-living stumptail monkeys (Macaca arctoides)

Behavioral changes before and around the time of puberty were studied in a longitudinal manner in male and female stumptail monkeys. Around the time of testicular descent (mean age: 3.3 years) males started to become more aggressive towards adult males. Within two years following testicular descent males rose in rank with the support of others and reached stable (sub)top positions in the dominance hierarchy. In the female rank-stabilization took place gradually between one year before and two years after first ovulation (mean age: 3.7 years). Copulatory activity began about two (in females) to two-and-a-half years (in males) before reproductive capacity was attained. Female copulatory activity began to rise about six months before first ovulation, when they started to copulate with adult males. In males copulatory frequency rose sharply between six and twelve months prior to testicular descent. Until a few months after testicular descent males could copulate openly in the group without interruption; from about 1 year following testicular descent virtually all copulations had to take place surreptitiously to avoid interruption by higher ranking adult males. It is postulated that this decreasing tolerance of adults may contribute to the process of peripheralization and migration of young adult males which occur in free ranging macaque groups.

The Orangutan: A Social Outsider

At first sight, the orangutan may well be the least spectacular of the great apes. In comparison with its African cousins, this solitary creature seems to lead a far less exciting life. Superficially, its social organization is exceptional in comparison with that of other diurnal primates. It is precisely this exceptional characteristic which makes the red ape an interesting test case for socio-ecological theorizing.

Deficits in social behavior in autism and their modification by a synthetic adrenocorticotrophic hormone (4–9) analog

When charting the structure of the social behavior of autistic children by means of an ethologically analyzed playroom session, deficits appeared in the reciprocity of eye-contact and in the location of verbal initiatives. These deficits in social behavior were beneficially influenced by treatment with the adrenocorticotrophic hormone (4–9) analog ORG 2766.