Variations in the predictability of a stressor have pronounced effects on the behavioural and physiological effects of stress in rats. It is reasonable to expect that variations in the predictability of husbandry routines thought to be aversive to animals might have similar effects on stress indices. Similarly, variations in the predictability of positive events, of which feeding is an obvious example, may affect welfare. This review examines the behavioural and physiological effects of the predictability of aversive and appetitive stimuli, and the application of experimental findings to animal husbandry in practice. It is argued here that two distinct but overlapping types of predictability exist. 'Temporal' predictability describes whether an event occurs at fixed or variable intervals, whereas 'signalled' predictability relates to the reliability of a signal preceding the event. This review examines the effects of each of these types of predictability in relation to positively and negatively perceived events, and examines the link between predictability and control. Recommendations are made for relatively simple and inexpensive modifications to husbandry routines that may be easy to incorporate into the schedules of busy staff yet could have a profound impact on the welfare of animals in their care.

Species comparisons of personality structure (i.e. how many personality dimensions and the characteristics of those dimensions) can facilitate questions about the adaptive function of personality in nonhuman primates. Here we investigate personality structure in the brown capuchin monkey (Sapajus apella), a New World primate species, and compare this structure to those of chimpanzees (Pan troglodytes), orangutans (Pongo spp.), and rhesus macaques (Macaca mulatta). Brown capuchins evolved behavioral and cognitive traits that are qualitatively similar to those of great apes, and individual differences in behavior and cognition are closely associated with differences in personality. Thus, we hypothesized that brown capuchin personality structure would overlap more with great apes than with rhesus macaques. We obtained personality ratings from seven sites on 127 brown capuchin monkeys. Principal-components analysis identified five personality dimensions (Assertiveness, Openness, Neuroticism, Sociability, and Attentiveness), which were reliable across raters and, in a subset of subjects, significantly correlated with relevant behaviors up to a year later. Comparisons between species revealed that brown capuchins and great apes overlapped in personality structure, particularly chimpanzees in the case of Neuroticism. However, in some respects (i.e. capuchin Sociability and Openness) the similarities between capuchins and great apes were not significantly greater than those between capuchins and rhesus macaques. We discuss the relevance of our results to brown capuchin behavior, and the evolution of personality structure in primates.

Male animals of many species use conspicuous coloration to attract mates. Among mammals, primates possess the most brilliant secondary sexual coloration. However, whether colour plays a part in primate female mate choice remains unknown. Adult male rhesus macaques undergo a hormonally regulated increased reddening of facial and anogenital skin during their mating season. We experimentally investigated whether red male facial coloration is preferred by simultaneously presenting female rhesus macaques (n = 6) with computer-manipulated pale and red versions of 24 different male faces. The duration and direction of gaze were measured to discern visual preferences. Females exhibited preferences for the red versions of male faces. It is proposed that male coloration might provide a cue to male quality.

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Increasing evidence suggests that personality structure differs between species, but the evolutionary reasons for this variation are not fully understood. We built on earlier research on New World monkeys to further elucidate the evolution of personality structure in primates. We therefore examined personality in 100 family-reared adult common marmosets (Callithrix jacchus) from three colonies on a 60-item questionnaire. Principal components analyses revealed five domains that were largely similar to those found in a previous study on captive, ex-pet, or formerly laboratory-housed marmosets that were housed in a sanctuary.The interrater reliabilities of domain scores were consistent with the interrater reliabilities of domain scores found in other species, including humans. Four domains---conscientiousness, agreeableness, inquisitiveness, and assertiveness---resembled personality domains identified in other nonhuman primates. The remaining domain, patience, was specific to common marmosets. We used linear models to test for sex and age differences in the personality domains. Males were lower than females in patience, and this difference was smaller in older marmosets. Older marmosets were lower in inquisitiveness. Finally, older males and younger females had higher scores in agreeableness than younger males and older females. These findings suggest that cooperative breeding may have promoted the evolution of social cognition and influenced the structure of marmoset prosocial personality characteristics.

The evolution of trichromatic colour vision by the majority of anthropoid primates has been linked to the efficient detection and selection of food, particularly ripe fruits among leaves in dappled light. Modelling of visual signals has shown that trichromats should be more efficient than dichromats at distinguishing both fruits from leaves and ripe from unripe fruits. This prediction is tested in a controlled captive setting using stimuli recreated from those actually encountered by wild tamarins (Saguinus spp.). Dietary data and reflectance spectra of Abuta fluminum fruits eaten by wild saddleback (Saguinus fuscicollis) and moustached (Saguinus mystax) tamarins and their associated leaves were collected in Peru. A. fluminum leaves, and fruits in three stages of ripeness, were reproduced and presented to captive saddleback and red-bellied tamarins (Saguinus labiatus). Trichromats were quicker to learn the task and were more efficient at selecting ripe fruits than were dichromats. This is the first time that a trichromatic foraging advantage has been demonstrated for monkeys using naturalistic stimuli with the same chromatic properties as those encountered by wild animals

Sleeping sites are an important aspect of an animal's ecology given the length of time that they spend in them. The sleep ecology of wild saddleback and mustached tamarins is examined using a long‐term data set covering three mixed‐species troops and 1,300+ tamarin nights. Seasonal changes in photoperiod accounted for a significant amount of variation in sleeping site entry and exit times. Time of exit was more closely correlated with sunrise than time of entry was with sunset. Both species entered their sleeping sites when light levels were significantly higher than when they left them in the morning. Troops of both species used >80 individual sites, the majority being used once. Mustached tamarins never used the same site for more than two consecutive nights, but saddlebacks reused the same site for up to four consecutive nights. Mustached tamarins slept at significantly greater heights than saddleback tamarins. There were consistent interspecific differences in the types of sites used. Neither the presence of infants, season, nor rainfall affected the types or heights of sites chosen. Sleeping sites were located in the central area of exclusive use more often than expected, and their position with respect to fruiting trees indicated a strategy closer to that of a multiple central place forager than a central place forager. These findings are discussed in light of species ecology, with particular reference to predation risk, which is indicated as the major factor influencing the pattern of sleeping site use in these species. Am J Phys Anthropol 2007. © 2007 Wiley‐Liss, Inc.

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