Factors affecting wounding aggression in a colony of captive chimpanzees (Pan troglodytes)

Previous research has suggested that chimpanzees (Pan troglodytes) display higher levels of aggression in captivity than in the wild. One of the challenges of captive management, therefore, is to balance the chimpanzees' need for social interaction with managements' desire to minimize wounding and aggression. Various captive studies have examined the effects of individual and social variables on the frequency of wounding aggression, but none have examined these variables simultaneously. We collected retrospective wounding data for severe wounds from 83 captive chimpanzees (36 males, 47 females) from January 1993 to December 2003. The context of the wounding event, including individual age and sex, group age and sex composition, group duration, and portion of the week (weekday vs. weekend) were collected. Logistic regression analysis was performed to determine which variables had a significant effect on the probability of a severe wounding event. The sex and age composition of the group, group duration, and portion of the week had a statistically significant association with wounding. All‐male groups (Odds Ratio (OR)=6.738) had the highest risk of wounding aggression, with uni‐male groups (OR=3.311) having the next largest. Compared to individuals in all sub‐adult groups, individuals in either all‐adult (OR=4.516) or mixed‐age (OR=3.587) groups had a higher risk of wounding. There was an inverse association between group duration and wounding (OR=0.821). Finally, there was an increased risk of wounding during the work week (OR=1.653). These results suggest that captive management should pay close attention to group composition, as well as levels of human activity, when devising strategies to reduce captive chimpanzee aggression. Zoo Biol 29:351–364, 2010. © 2009 Wiley‐Liss, Inc.     

Electrocardiogram abnormalities in captive chimpanzees (Pan troglodytes)

Although cardiovascular disease is the leading cause of death in the captive chimpanzee population, little is known about the prevalence and etiology of heart disease in this species. We reviewed the physical exam records of 265 common chimpanzees (Pan troglodytes) for electrocardiogram abnormalities. During the 24-mo period reviewed (August 2003 through August 2005), 34 animals were diagnosed with cardiac arrhythmias consisting of ventricular arrhythmias, supraventricular arrhythmias, conduction disturbances, mixed arrhythmias, and bradycardia. The incidence of cardiac arrhythmia was significantly higher in male animals, chimpanzees 20 to 39 y old, and those with structural heart disease. Incidence of cardiac arrhythmia was not significantly higher in animals with hypertension, hyperlipidemia, or chronic viral infections. During the retrospective period, 7 animals with cardiac arrhythmias died or were euthanized. Mortality was significantly higher in animals with ventricular arrhythmias compared with those without ventricular arrhythmias. We conclude that in the common chimpanzee, age, male gender, and structural heart disease are risk factors for developing cardiac arrhythmias and that ventricular arrhythmias are risk factors for mortality.     

Videotapes as enrichment for captive chimpanzees (Pan troglodytes)

The effectiveness of showing videotapes to captive chimpanzees as an environmental enrichment was quantitatively tested. The responses of 10 subjects (3 adult males and 7 adult females) to videotapes of chimpanzees engaging in a variety of behaviors, to videotapes of other animals and humans, and to television programs were compared. Data collection consisted of 20-minute, continuous sampling tests while various videotapes were shown. A total of 400 tests were conducted. Multivariate analysis of variance was applied to measure differences in the duration of eight categories of behavior across videotapes of varying content. No general behavioral differences in response to the tapes based on sex or housing were revealed. However, with the behavior of monitor-watching analyzed alone, we found that individually housed subjects watched the videotapes more than socially housed subjects. When viewing time was averaged across all videotapes, the chimpanzees watched the monitor a mean of 38.4% of the time available. The chimpanzees' behavior varied significantly only when they were watching the videotapes of various human and chimpanzee activities and not when watching a blank screen. A Pearson's correlation indicated that subjects habituated to repeated presentations of the videotapes, although the effect was small numerically. Although this type of enrichment did not extensively alter behavior, it did occupy a significant portion of the subjects' activity budget; thus, the amount of time spent watching the video stimuli indicated that videotapes may be a useful enrichment for captive chimpanzees. Zoo Biol 19:541-551, 2000. Copyright 2000 Wiley-Liss, Inc.     

Possible roles of consolation in captive chimpanzees (Pan troglodytes)

Empathy is a necessary prerequisite for the occurrence of consolation. The term "consolation" contains a hypothesis about function, which is distress alleviation. The present study aims to confirm the occurrence of consolation in captive chimpanzees via the post-conflict/matched-control method (PC-MC) and to suggest its possible roles. We collected 273 PC-MC pairs in the group of Pan troglodytes housed in the ZooParc de Beauval (France). We confirmed the presence of consolatory contacts (mean level of consolation, 49.5% +/- 22.3% SEM) in the colony. Consolation rates were significantly higher than reconciliation levels (mean level of reconciliation, 28.9% +/- 16.8% SEM). The level of consolation was greater in the absence of reconciliation than in the presence of it, suggesting that consolation might be an alternative behavior. As friendship and relatedness did not influence the occurrence of consolation, they did not seem to be the best prerequisites for this behavioral mechanism, at least in this chimpanzee colony. Affinitive contacts with third parties were significantly more frequent when the victim called attention to itself during severe aggressions by screaming. These high-pitched sounds seem to be useful in eliciting aid from conspecifics, as occurs in young humans. The occurrence of consolation reduced the likelihood of further attacks among group-members. From this perspective, both victims and consolers most likely gain potential advantages by interacting with each other when aggression is particularly severe, reconciliation is not immediate, and consequently social stress reaches high levels.     

Neighbor effect: evidence of affiliative and agonistic social contagion in captive chimpanzees (Pan troglodytes)

Previous studies of captive chimpanzees have demonstrated the "neighbor effect," or social contagion, with respect to agonistic vocalizations and behaviors. The present study considers whether there is a relationship between behavior patterns in focal animals and the auditory signals of neighboring social groups. Using focal-group sampling, we collected 172.5 hr of data on 51 subjects (25 females and 26 males) housed in 10 social groups. We performed two-tailed Wilcoxon matched-pairs signed-rank tests to determine whether the relative frequency of the vocalizations (high vs. low) affected the behaviors. In keeping with past research, we found that agonistic noises and vocalizations from neighboring social groups had a significant effect on the rates of focal-group bluff displays, pant-hoots, and aggression (P<0.05). In addition, we also found significant relationships between grooming behavior and vocalizations in focal groups, and grooming vocalizations from neighboring groups (P<0.05). The results suggest that social contagion is not limited to aggressive behaviors, but also occurs for affiliative behavior patterns.     

Controllability in environmental enrichment for captive chimpanzees (Pan troglodytes)

This study considers the use of nonsocial environmental enrichment by captive chimpanzees at the Primate Foundation of Arizona. The goal was to determine whether a relationship existed between controllability of enrichment items by captive chimpanzees and frequency of use. The study measured controllability, the ability of nonhuman animals to alter aspects of their environment by the potential destructibility of the enrichment item. This study examined additional factors that may affect enrichment use: individual age, sex, rearing history, social group composition, and availability of outdoor access. The chimpanzees in the study used destructible items—the enrichment category with the highest level of controllability—more than indestructible items across all age, sex, and rearing classes. Thus, controllability seems to be an important factor in chimpanzee enrichment. Younger individuals and groups with outdoor access used enrichment more than did older individuals and groups with indoor-only access. Individual sex, rearing history, and social group composition had minimal effects on enrichment use. These results support the importance of control to captive chimpanzees and further enable captive management to customize enrichment programs to the needs of particular animals.     

Hand preference in a captive island group of chimpanzees (Pan troglodytes)

Morphological cerebral asymmetries in chimpanzee brains, similar to those found in humans, in whom they are associated with speech and handedness, suggest the possibility of functional lateralization in the chimpanzee. This possibility was investigated by examining hand preferences in an island group of five chimpanzees on a series of unimanual and bimanual tasks that are diagnostic of human hand and cerebral dominance. Each subject was tested in a double compartment cage on three unimanual nonsequential, three unimanual sequential, and three bimanual coordination tasks. One of the three unimanual sequential tasks was a bar-press task that is analogous to the commonly used human finger-tapping task. For the unimanual tasks, exclusive of the bar-press, the chimpanzees showed a highly individualistic pattern of hand preference that did not change as a function of task complexity. On the bar-press task, four of five subjects produced higher rates with one hand compared to the other; however, relative hand performance on this task was unrelated to hand preference on the other unimanual tasks. For the group of subjects, performance rates did not differ between the left and right hands; however, a practice effect was observed for the right hand in all subjects. The bimanual tasks also revealed a complex pattern of individual handedness, with no trends apparent for the group as a whole. Consistent with previous findings, the results from these tests on this group of five chimpanzees suggest that cerebral morphological asymmetries in the chimpanzee are not associated with motor dominance as reflected in handedness.     

Variation and context of yawns in captive chimpanzees (Pan troglodytes)

Primate yawns are usually categorized according to context (e.g. as a threat, anxious, or rest yawn), but there has been little consideration of whether these yawns are best regarded as a unitary behavior that only differs with respect to the context in which it is observed. This study examined the context and precise morphology of yawns in a group of 11 captive chimpanzees. Focal video sampling was used to describe the morphology and intensity of 124 yawns using ChimpFACS, a system for coding facial movements. Two distinct forms of yawn were identified, a full yawn and a yawn which is modified by additional actions that reduce the mouth aperture. These modified yawns may indicate some degree of voluntary control over facial movement in chimpanzees and, consequently, multiple functions of yawning according to context. To assess context effects, mean activity levels (resting, locomotion, and grooming) and scratching rates were compared one minute before and after each yawn. Locomotion was significantly increased following both types of yawn, whereas scratching rates significantly increased following modified yawns but decreased following full yawns. In terms of individual differences, males did not yawn more than females, although male yawns were of higher intensity, both in the degree of mouth opening and in the amount of associated head movement. These data indicate that yawning is associated with a change in activity levels in chimpanzees, but only modified yawns may be related to increased arousal. Different types of yawn can therefore be differentiated at the morphological level as well as context level. Am. J. Primatol. 72:262–269, 2010. © 2009 Wiley‐Liss, Inc.     

Features of meat digestion by captive chimpanzees (Pan troglodytes)

The pronounced carnivory of many human populations contrasts sharply with feeding habits of other Hominoidea. Of extant great apes, only chimpanzees (Pan spp.) actively seek out vertebrate prey, but meat is only a minor portion of their diet. Some accounts suggest that wild chimpanzees digest prey inefficiently. To investigate the capacity of chimpanzees to digest meat, feeding trials were carried out on three captive chimpanzees (Pan troglodytes) using a fixed amount of nonpurified diet with and without a predetermined amount of boned cooked chicken. The results showed no significant differences in the rate of passage of digesta and digestion of diets with and without chicken. Meat ingestion did not change the nitrogen (N) concentration of feces or the total amount of N defecated. Visual inspection of fecal matter showed no evidence of undigested meat. Taken together, the results indicate that chimpanzees are able to digest meat of the type and quantity consumed during these trials.     

圈养黑猩猩血液生理生化指标测定

正动物园作为综合保护、科普宣传与公众教育的重要场所,在濒危物种的迁地保护工作中发挥着十分重要的作用(Kleiman et al.,2010)。然而,不同的濒危物种在生理学及生活史方面存在很大差异;加之部分物种的生物学信息匮乏,使得动物园的饲养繁育和疾病防控工作面临重大挑战。在常规体检及疾病诊断时,血液参数值有助于对动物机体的临床检查与诊断,解读动物的生理、营养和病理状态(胡翊群,2004;Etim et al.,2014),是及时发现动物     

Synchrony of estrous swelling in captive group-living chimpanzees (Pan troglodytes)

Recent findings suggest that menstrual synchrony may occur in humans and is more dependent on factors of close personal association than simple prox imity. Part I of this study analyzed the estrous cycles of 10 captive group living chimpanzees (Pan troglodytes) housed in two separate groups in the same building. Each group contained at least one male. The mean discrepan cies for (1) the approximate day of ovulation (last day of maximum swelling) and (2) the day of onset of estrous swelling were determined for all possible pairs within groups and compared to the mean discrepancies of pairs between groups. With respect to the probable day of ovulation, the mean discrepancy of animals caged together was 8.0 days and that of animals caged separately was 10. 7 days. Comparing the onset of estrous swelling, the mean between groups was 10.4 days, whereas females caged together averaged only 5.7 days. A repeated-measures analysis of variance indicated a significant group effect in the onset of estrous swelling (F = 5.68,p < 0.05), whereas there was no significant difference between the animals caged together and those caged separately with respect to the last day of maximum swelling (F = 1.37, NS). Part II of the study compared the onset of the first postpar tum estrus (PPE) to the onset of estrus in cagemates. During a 6-year period, 13 females exhibited 33 PPEs while in social contact with cycling females. Of 86 paired comparisons, the PPE onset of 43 (50%) occurred with in 6 days of the swelling onset of a cagemate. The results suggest that, as in other species (including humans), the social contact and time spent together influence the synchrony of chimpanzee estrous cycles, especially in terms of swelling onset. The synchrony of estrous swelling and possible mediation by olfactory and/or hormonal cues are discussed as they relate to chimpanzee social structure and female reproductive strategy.     

Familial incidence of multiple births in a colony of chimpanzees (Pan troglodytes)

This paper describes the incidence of multiple births in the Yerkes Chimpanzee colony for a period of about 63 years. Pedigrees are presented for all multiple births. They demonstrate the recurrence of twins in relatively few family lines which can be traced back to a small number of ancestors. The findings suggest that twinning is a family trait in chimpanzees and they support the hypothesis that the incidence of multiple births is genetically influenced in this colony. In addition, a relatively high level of inbreeding may have enhanced the incidence of multiple births in these family lines. Similar findings are known from human populations.     

Bed-building in captive chimpanzees (Pan troglodytes): the importance of early rearing

In the wild, great apes sleep in beds they make by successively bending branches into an interwoven platform. These beds are functionally more closely related to human beds than they are to the nests and tree-holes used by other primate species. The idea that bed-building by great apes is learned behavior that is dependent on appropriate early experiences has been proposed but never fully tested. In the present study this hypothesis was indirectly tested in 73 captive adult chimpanzees (Pan troglodytes; 27 wild-born and 46 captive-born). Bed-building and use were tested experimentally by the introduction of three sets of bedding materials. Over 200 hr of scan-sampling data were collected during 45-min observations following introduction of the bedding material. The wild-born subjects built and used beds significantly more often than the captive-born subjects. Also, wild-born subjects used more complex techniques during construction. Captive-born subjects that were mother-reared through early adolescence spent more time building and using beds than their nursery-reared counterparts. These differences remained consistent even when previous adult experience with bedding (measured as naturalistic vs. traditional housing) was accounted for. These results suggest that bed-building is a learned behavior that requires early experience and practice for acquisition.     

Development of guidelines for assessing obesity in captive chimpanzees (Pan troglodytes)

Many captive chimpanzees (Pan troglodytes) are subjectively considered to be overweight or obese. However, discussions of obesity in chimpanzees are rare in the literature, despite the acknowledged problem. No study to date has systematically examined obesity in captive chimpanzees. This project develops guidelines for defining obesity in captive chimpanzees through the examination of morphometric and physiologic characteristics in 37 adult female and 22 adult male chimpanzees. During each animal's biannual physical exam, morphometric data was collected including seven skinfolds (mm), body mass index (BMI), waist‐to‐hip ratio (WHR), and total body weight (kg). The morphometric characteristics were correlated with triglycerides and serum glucose concentration, to test the utility of morphometrics in predicting relative obesity in captive chimpanzees. Abdominal skinfold (triglyceride: F=3.83, P=0.05; glucose: F=3.83, P=0.05) and BMI (triglyceride: F=10.42, p=0.003; glucose: F=6.20, P=0.02) were predictive of increased triglycerides and serum glucose in females; however no morphometric characteristics were predictive of relative obesity in males. Results suggest that no males in this population are overweight or obese. For females, there were additional significant differences in morphometric (skinfolds, BMI, WHR, total body weight) and physiologic measurements (systolic and diastolic blood pressure, red blood cells) between individuals classified overweight and those classified non‐overweight. Skinfold measurements, particularly abdominal, seem to be an accurate measure of obesity and thus potential cardiovascular risk in female chimpanzees, but not males. By establishing a baseline for estimated body fat composition in female captive chimpanzees, institutions can track individuals empirically determined to be obese, as well as obesity‐related health problems. Zoo Biol 0:1–12, 2007. © 2007 Wiley‐Liss, Inc.     

Response of fecal cortisol to stress in captive chimpanzees (Pan troglodytes)

This study examined whether fecal cortisol could be used as an index of stress responses. The stress responsiveness of fecal cortisol was tested with a stressor known to stimulate adrenal activity, the stress of anesthesia. Daily fecal and urine samples were collected from four captive chimpanzees (Pan troglodytes) before and after anesthetizations with Telazol^®/Ketasat^®. Tests of assay validity indicated that cortisol was measurable in chimpanzee fecal extracts. Fecal cortisol concentrations were significantly elevated 2 days after anesthetization, with elevations in seven of the eight treatments. The posttreatment peak was significantly greater than baseline values in three of the four subjects. Both fecal concentrations and proportionate increases in response to stress were significantly correlated with the corresponding values in urinary cortisol, confirming the stressfulness of these procedures and the stress responsiveness of fecal cortisol. These findings provide evidence for the application of fecal cortisol as a noninvasive index of physiologic stress in nonhuman primates. Am. J. Primatol. 44:57–69, 1998. © 1998 Wiley-Liss, Inc.     

Morphometric variables related to metabolic profile in captive chimpanzees (Pan troglodytes)

Obesity is a risk factor for several diseases including type 2 diabetes and cardiovascular disease. The aim of this study was to compare the relationships of waist circumference and body weight with circulating markers of metabolic, cardiovascular, and hepatic function in chimpanzees (Pan troglodytes). After a 12-h fast, blood was collected from 39 adult captive chimpanzees for measurement of serum glucose, BUN, creatinine, albumin, cholesterol, ALT, AST, ALP, total and direct bilirubin, triglyceride, and insulin, and waist circumference and body weight were measured. Waist circumference was positively correlated with systolic and diastolic blood pressure, glucose, insulin resistance as estimated by the homeostatic model assessment method, and albumin in female chimpanzees and with triglyceride in female and male chimpanzees. Body weight was correlated significantly with systolic and diastolic blood pressure in female chimpanzees and triglyceride in male chimpanzees. Male chimpanzees were heavier and had lower diastolic blood pressure, greater creatinine, albumin, AST, ALP, total bilirubin, and direct bilirubin values than did female chimpanzees. The relationships between waist circumference and blood pressure and triglyceride are consistent with those reported in humans and other primate species. In conclusion, our study is the first work to demonstrate a relationship between waist circumference and metabolic risk factors in chimpanzees. Results demonstrated that waist circumference was associated with more metabolic risk factors than was body weight, particularly in female chimpanzees.     

Objective evaluation of a behavioral enrichment device for captive chimpanzees (Pan troglodytes)

A quantitative evaluation was made of a food puzzle designed to be a behavioral enrichment device for captive chimpanzees. Subjects were two social groups of chimpanzees housed in semifree-ranging conditions at the University of Texas Science Park in Bastrop. Subjects used the device for a mean of 91.6 minutes after it was filled with peanuts. Group levels of agonistic interactions, displays, coprophagy, regurgitation, excessive grooming, and consumption of wood were not significantly altered by the use of the peanut box. However, the data indicate that some of these categories of behavior were significantly increased or decreased in individual animals. Although the food puzzle box appears to be a promising behavioral enrichment tool, the necessity of recognizing individual differences in response to environmental manipulations must be emphasized.