Infant cradling in a captive mother gorilla

The purpose of the study presented here was to investigate the handedness and cradling preferences of a mother gorilla (Gorilla gorilla) from the Metro Toronto Zoo. The study also examined preferences for handedness for each member of the captive group. Observational data were collected using scan sampling at 60‐sec intervals. Handedness was determined with a coordinated bimanual tube test using peanut butter spread on the interior of a PVC tube. Our findings were largely consistent with the literature on laterality in African apes by documenting a left‐side cradling bias for one apparently ambidextrous captive gorilla mother. This bias was associated with a left head positioning preference by her infant. Although based on a single mother/infant pairing, this study indicates that cradling bias is not always determined by maternal handedness. Zoo Biol 27:420–426, 2008. © 2008 Wiley‐Liss, Inc.     

Beiträge zur Menschenaffenhaltung im Zoo Berlin nach 1945. 3. Mitteilung: Gorillas (Gorilla gorilla)

Since 1956 were Western Lowland Gorillas (Gorilla gorilla gorilla) kept in Berlin Zoo, counted in the period after 1945. The first offspring was born in 1964. Up to now 9 Gorillas were born in Berlin Zoo, of which 8 were raised, some of them artificial. The oldest Gorilla is “Fatou”, she is now in an age of 53.     

Blood groups in the species survival plan®, European endangered species program,and managed in situ populations of bonobo (Pan paniscus), common chimpanzee (Pan troglodytes), gorilla (Gorilla ssp.), and orangutan (Pongo pygmaeus ssp.)

Blood groups of humans and great apes have long been considered similar, although they are not interchangeable between species. In this study, human monoclonal antibody technology was used to assign human ABO blood groups to whole blood samples from great apes housed in North American and European zoos and in situ managed populations, as a practical means to assist blood transfusion situations for these species. From a subset of each of the species (bonobo, common chimpanzee, gorilla, and orangutans), DNA sequence analysis was performed to determine blood group genotype. Bonobo and common chimpanzee populations were predominantly group A, which concurred with historic literature and was confirmed by genotyping. In agreement with historic literature, a smaller number of the common chimpanzees sampled were group O, although this O blood group was more often present in wild‐origin animals as compared with zoo‐born animals. Gorilla blood groups were inconclusive by monoclonal antibody techniques, and genetic studies were inconsistent with any known human blood group. As the genus and, specifically, the Bornean species, orangutans were identified with all human blood groups, including O, which had not been reported previously. Following this study, it was concluded that blood groups of bonobo, common chimpanzees, and some orangutans can be reliably assessed by human monoclonal antibody technology. However, this technique was not reliable for gorilla or orangutans other than those with blood group A. Even in those species with reliable blood group detection, blood transfusion preparation must include cross‐matching to minimize adverse reactions for the patient. Zoo Biol 30:427–444, 2011. © 2010 Wiley‐Liss, Inc.     

Applying Behavioral Conditioning to Identify Anticipatory Behaviors

The ability to predict regular events can be adaptive for nonhuman animals living in an otherwise unpredictable environment. Animals may exhibit behavioral changes preceding a predictable event; such changes reflect anticipatory behavior. Anticipatory behavior is broadly defined as a goal-directed increase in activity preceding a predictable event and can be useful for assessing well being in animals in captivity. Anticipation may look different in different animals, however, necessitating methods to generate and study anticipatory behaviors across species. This article includes a proposed method for generating and describing anticipatory behavior in zoos using behavioral conditioning. The article also includes discussion of case studies of the proposed method with 2 animals at the San Francisco Zoo: a silverback gorilla (Gorilla gorilla gorilla) and a red panda (Ailurus fulgens). The study evidence supports anticipation in both animals. As behavioral conditioning can be used with many animals, the proposed method provides a practical approach for using anticipatory behavior to assess animal well being in zoos.     

笼养大猩猩行为研究中瞬时扫描最适取样时间间隔的确定

2009年9～12月以4只大猩猩(Gorilla gorilla)为研究对象,应用瞬时扫描取样法观察记录其活动行为,建立不同取样间隔与数据准确性和数据独立性的线性回归方程,计算变量系数和常数项的95%置信区间,进而确定瞬时扫描法的最适取样间隔。研究结果表明,大猩猩活动主要集中于上午10:00～11:00时和下午14:00～15:00时(χ2=19.110,df=4,P=0.001),不同大猩猩个体间活动行为存在显著差异(Kruskal Wallis Test,χ2=11.229,df=3,P=0.011)。随着取样间隔的增大,间隔取样与连续取样数据的相关系数呈下降趋势,满足数据准确性需求的最适取样间隔为3～13 min,随取样间隔的增大,数据独立可能性逐渐升高,其中满足数据独立性需求的最适取样间隔为2～8 min。综合考虑以上两种因素,确定针对大猩猩活动行为的瞬时扫描取样的最适间隔为3～8 min。     

Brain organization of gorillas reflects species differences in ecology

Gorillas include separate eastern (Gorilla beringei) and western (Gorilla gorilla) African species that diverged from each other approximately 2 million years ago. Although anatomical, genetic, behavioral, and socioecological differences have been noted among gorilla populations, little is known about variation in their brain structure. This study examines neuroanatomical variation between gorilla species using structural neuroimaging. Postmortem magnetic resonance images were obtained of brains from 18 captive western lowland gorillas (Gorilla gorilla gorilla), 15 wild mountain gorillas (Gorilla beringei beringei), and 3 Grauer's gorillas (Gorilla beringei graueri) (both wild and captive). Stereologic methods were used to measure volumes of brain structures, including left and right frontal lobe gray and white matter, temporal lobe gray and white matter, parietal and occipital lobes gray and white matter, insular gray matter, hippocampus, striatum, thalamus, each hemisphere and the vermis of the cerebellum, and the external and extreme capsules together with the claustrum. Among the species differences, the volumes of the hippocampus and cerebellum were significantly larger in G. gorilla than G. beringei. These anatomical differences may relate to divergent ecological adaptations of the two species. Specifically, G. gorilla engages in more arboreal locomotion and thus may rely more on cerebellar circuits. In addition, they tend to eat more fruit and have larger home ranges and consequently might depend more on spatial mapping functions of the hippocampus. Am J Phys Anthropol 156:252–262, 2015. © 2014 Wiley Periodicals, Inc.     

Non‐invasive fecal hormone analysis and behavioral observations for monitoring stress responses in captive western lowland gorillas (Gorilla gorilla gorilla)

Non‐invasive techniques for monitoring the stress response in captive western lowland gorillas (Gorilla gorilla gorilla) were investigated. Fecal samples for cortisol measurement and concurrent behavioral data were collected from six individuals in a socially housed gorilla group (one adult male, three adult females and their three offspring) over a 7‐month period. Despite inter‐individual variation in the dynamics of fecal cortisol concentrations over time, several major secretory peaks coincided across individuals. High cortisol concentrations in feces were correlated with induced stressors or behavioral observations indicating high social tension, with a 1–2 day lag period. Entry progression order of the gorillas into a den complex and a supplant‐based dominance index were suitable indicators of overall dominance hierarchies, and fluctuations over time reflected periods of instability. Diurnal variation in fecal cortisol was not apparent when comparing afternoon and morning samples, however the sample collection interval was relatively short (3–5 hr). These results demonstrate the feasibility of monitoring stress responses based on the dynamics of both fecal cortisol excretion and behavior. This non‐invasive approach may be used for gauging responses to changes in husbandry, environment and group structure of captive gorillas. Zoo Biol 0:1–15, 2005. © 2005 Wiley‐Liss, Inc.     

Sexual behavior in female western lowland gorillas (Gorilla gorilla gorilla): evidence for sexual competition

Previous research in gorillas suggests that females engage in post‐conception mating as a form of sexual competition designed to improve their own reproductive success. This study focused on sexual behaviors in a newly formed group of western lowland gorillas (Gorilla gorilla gorilla) housed at Zoo Atlanta. All females engaged in mating outside their conceptive periods, although there was individual variation in the frequency of the behavior. An analysis of the presence/absence of sexual behavior found females, regardless of reproductive condition, were more likely to engage in sexual behavior on days when other females were sexually active. On these “co‐occurrence” days, females were significantly more likely to solicit the silverback, but copulations did not differ from expectation. The results find further evidence for sexual competition among female gorillas and suggest that this may occur throughout their reproductive cycle rather than only during pregnancy. Am. J. Primatol. 71:587–593, 2009. © 2009 Wiley‐Liss, Inc.     

The Occurrence and Ape-to-Ape Transmission of the Entodiniomorphid Ciliate Troglodytella abrassarti in Captive Gorillas

ABSTRACT. Entodiniomorphid ciliates are often present in the colons of wild apes. In captive apes the infection tends to gradually disappear, with the exception of Troglodytella abrassarti . We used fecal examinations to screen the gorillas ( Gorilla gorilla gorilla ) in European (Czech Republic, UK) and Australian Zoos to explore the ape-to-ape transmission pattern of T. abrassarti . Gorillas from two out of three European Zoos were positive for T. abrassarti , while gorillas from the Australian Zoo were negative. We documented a horizontal transmission of T. abrassarti to a non-infected adult gorilla introduced into a Troglodytella -positive group in the Prague Zoo and traced the origin of the ciliate infection to the Paignton Zoo (UK) using serial fecal examinations. During this study, two infant gorillas born in the Prague Zoo (CZ) first became positive for T. abrassarti at the age of 9 mo. Ciliate morphology and the sequencing of the small subunit rRNA gene and the internal transcribed spacer rDNA spacer region revealed that T. abrassarti affects both captive gorillas and chimpanzees. We conclude that zoo transport plays a major role in the distribution of T. abrassarti among captive gorillas.     

Behavioral Ecology of Sympatric Chimpanzees and Gorillas in Bwindi Impenetrable National Park,Uganda: Diet

Via a field study of chimpanzees (Pan troglodytes schweinfurthii) and gorillas (Gorilla gorilla beringei) in Bwindi Impenetrable National Park, Uganda, we found that their diets are seasonally similar, but diverge during lean seasons. Bwindi chimpanzees fed heavily on fruits of Ficus sp., which were largely ignored by the gorillas. Bwindi gorilla diet was overall more folivorous than chimpanzee diet, but was markedly more frugivorous than that of gorillas in the nearby Virunga Volcanoes. During 4 mo of the year Bwindi gorilla diet included more food species than that of the chimpanzees. Three factors in particular—seasonal consumption of fibrous foods by gorillas, interspecific differences in preferred fruit species, and meat consumption by chimpanzees—contributed to dietary divergence between the two species. When feeding on fruits, gorillas ate Myrianthus holstii more frequently than chimpanzees did, while chimpanzees included more figs in their annual diet. Chimpanzee diet included meat of duikers and monkeys; gorilla frequently consumed decaying wood.     

An experimental study of nettle feeding in captive gorillas

Mountain gorillas (Gorilla beringei beringei) in Karisoke, Rwanda, feed on the stinging nettle Laportea alatipes by means of elaborate processing skills. Byrne [e.g. Philosophical Transactions of the Royal Society of London, Series B, Biological Sciences 358:529–536, 2003] has claimed that individuals acquire these skills by means of the so‐called program‐level imitation, in which the overall sequence of problem‐solving steps (not the precise actions) is reproduced. In this study we present western lowland gorillas (Gorilla gorilla gorilla) with highly similar nettles. Twelve gorillas in three different groups (including also one nettle‐naïve gorilla) used the same program‐level technique as wild mountain gorillas (with differences mainly on the action level). Chimpanzees, orangutans, and bonobos did not show these program‐level patterns, nor did the gorillas when presented with a plant similar in structural design but lacking stinging defenses. We conclude that although certain aspects (i.e. single actions) of this complex skill may be owing to social learning, at the program level gorilla nettle feeding derives mostly from genetic predispositions and individual learning of plant affordances. Am. J. Primatol. 70:584–593, 2008. © 2008 Wiley‐Liss, Inc.     

Seed dispersal effectiveness of the western lowland gorilla (Gorilla gorilla gorilla) in Gabon

The quantitative and qualitative aspects of seed dispersal by the western lowland gorilla (Gorilla gorilla gorilla) were investigated in Gabon. Fresh faeces were collected and washed to identify and count the seeds. Seed germinability after gut passage was estimated with trials in a nursery at the study site. To assess the impact of gut passage on germination success and delay, comparative trials were run with four treatments: (i) gut passed seeds cleaned of faeces, (ii) gut passed seeds within a faecal matrix, (iii) seeds from fresh fruits surrounded by pulp, and (iv) seeds from fresh fruits cleaned of pulp. The analysis of 180 faecal units resulted in the identification of 58 species of seed. Germination trials were realized for 55 species and the mean germination success reached 46%. The impact of gut passage was investigated for Santiria trimera and Chrysophyllum lacourtianum; both species displayed higher germination success after ingestion. This study shows that gorillas effectively disperse seeds of numerous plant species, many of which provide timber or nontimber forest products or are typical of Gabonese forests. Considering the high‐quality of gorilla deposition sites, gorillas is thought to play a unique role in the dynamics of Central African forest.     

Quantification and excretion profiles of pteridines in primate urine.

Biopterin, 6-hydroxymethyl-pterin, isoxanthopterin, neopterin and, pterin were quantified in stress-free collected spontaneous morning urine samples from Callithrix jacchus, Saguinus fuscicollis, Saguinus labiatus, Saimiri sciureus, Presbytis entellus, Cercopithecus albogularis, Cercocebus torquatus, Macaca fascicularis, Hylobates concolor, Pongo pygmaeus, and Gorilla gorilla. In most species, biopterin was the most frequent urinary pteridine followed by neopterin. Sex differences in biopterin and neopterin excretion were observed in Gorilla gorilla and Pongo pygmaeus. Pterin and isoxanthopterin were only present in minor concentrations. 6-hydroxymethyl-pterin was barely detectable and not present in the urine of Saguinus labiatus, Saimiri sciureus, and both male Gorilla gorilla and Pongo pygmaeus.     

Changes in nearest‐neighbor associations in a captive group of western lowland gorillas after the introduction of five hand‐reared infants

The successful management of a captive gorilla population often necessitates the hand‐rearing of infants and their subsequent re‐integration into social groups of conspecifics. In the present study we quantified the changes in nearest‐neighbor associations in a group consisting of a silverback male, three adult females, and two sub‐adult females after the introduction of five hand‐reared infants. Additionally, we examined the associations among kin and non‐kin group members to determine whether genetic relatedness was a factor influencing the integration of the infants into the group and the subsequent patterns of association among infants and adults. Results showed that after the introduction, the silverback male spent >60% of his time in close proximity to an infant and 10% of his time within a “cluster” of infants. There was a significant change in a female's nearest‐neighbor associations; however, the change did not include an infant. The most significant finding among infants was a strong bias by each to associate with another infant. When the infants associated with an adult, three of the five associated most with the silverback male (P < 0.001), whereas the other two infants distributed their time among all the adults. The most significant change in behavior patterns was exhibited by one of the sub‐adult females who displayed parental behaviors 18% of the time compared to <1% for all other females. Adults and one sub‐adult female associated significantly more often with related infants compared to unrelated infants (P < 0.025), and the infants showed a bias to associate with another related infant (P < 0.0001). Results of an infant's association with an adult showed that three of the five infants preferred to associate with a related adult (P < 0.0001). An individual's age, sex, and behavioral profile may have also influenced association patterns among group members. These findings lend strong support to the importance of peer groups and the presence of a silverback male for facilitating the integration of hand‐reared infants into established adult groups. Zoo Biol 18:261–278, 1999. © 1999 Wiley‐Liss, Inc.     

Body signals used during social play in captive immature western lowland gorillas

The play face is a well-established play signal in nonhuman primates that functions to invite play and convey a playful intent. However, recent evidence indicates that some species display repertoires of play signals that may have more specific meanings related to particular aspects of play. Furthermore, previous studies have inconsistently categorized gorilla behaviors as play signals versus actual play. Here we aim to identify behaviors displayed by two immature captive western lowland gorillas (Gorilla gorilla gorilla) at the Buffalo Zoo that meet three necessary criteria to be considered play signals. Specifically, we (1) investigate whether 21 candidate signals are significantly different from actual play behaviors, (2) and from similar signals used in non-play contexts, and (3) determine whether they predict the occurrence of social play. The results indicate that at least 18 of the 21 candidate signals have strong support for classification as play signals. These findings represent first steps in determining the function of multiple play signals in gorillas.     

Behavioural changes of two female zoo-held western lowland gorillas,after the introduction of a silverback male

Behavioural observations of the two female western lowland gorillas (Gorilla gorilla gorilla) composing an all-female group in Artis Royal Zoo (Amsterdam, the Netherlands) were evaluated. The two females had been observed for one-hr periods over a 166- day period, divided into a period before, and a period after the introduction of a new silverback male. Step intervention analysis showed that in both females locomotion and stereotypic behaviour significantly decreased after the introduction of the silverback. In one of the two females the public interaction also decreased significantly.     

A survey of the apes in the Dzanga-Ndoki National Park, Central African Republic: a comparison between the census and survey methods of estimating the gorilla (Gorilla gorilla gorilla) and chimpanzee (Pan troglodytes) nest group density

A survey of apes was carried out between October 1996 and May 1997 in the Dzanga sector of the Dzanga‐Ndoki National Park, Central African Republic (CAR), to estimate gorilla (Gorilla gorilla gorilla) and chimpanzee (Pan troglodytes) densities. The density estimates were based on nest counts. The strip transect census and the line transect survey method (Standing Crop Nest Count) were used to estimate the gorilla nest group density. The strip transect has been most commonly used to date. It assumes that all nest groups within the width of the strip are detected, but as this assumption is easily violated in the dense tropical rain forest, the line transect survey was also used. In this method, only the nest groups on the transect line itself should be detected. This method proved to be an adequate and easy technique for estimating animal densities in dense vegetation. The gorilla density of 1.6 individuals km^?2 (line transect survey method) found for the Dzanga sector is one of the highest densities ever reported in the literature for the Western lowland gorilla. The density estimate for chimpanzees was 0.16 individuals km^?2 (census method). The results of this study confirm the importance of the Dzanga‐Ndoki National Park for primate conservation.     

ORIGINAL ARTICLE: Medical and surgical management of reproductive neoplasia in two western lowland gorillas (Gorilla gorilla gorilla)

Background Reports of female reproductive tract neoplasia are infrequent in great apes. Methods Two captive‐born, female western lowland gorillas (Gorilla gorilla gorilla) housed at the North Carolina Zoological Park were diagnosed with reproductive neoplasia. Results The first gorilla had uterine endometrial thickening and uterine fibroids diagnosed during a routine annual examination. Subsequently, the animal underwent several uterine curettage procedures in an attempt to debulk the uterine mass. Biopsy results indicated uterine adenocarcinoma. The animal was treated with an ovariohysterectomy followed by a combination of megestrol acetate and medroxyprogesterone acetate. The second gorilla was diagnosed with squamous cell carcinoma of the vagina, cervix, and uterus after presenting for intermittent vaginal bleeding of 1‐month duration. This animal underwent palliative radiation therapy, receiving two rounds of radiation treatment 8 weeks apart. Conclusions The following report describes the diagnosis and management of the two cases.     

Paternity determination in captive lowland gorillas and orangutans and wild mountain gorillas by microsatellite analysis

Paternity exclusion studies provide useful information for testing certain theories of behavioral ecology and for the management and conservation of both wild and captive populations of endangered species. This study used eight human nuclear microsatellite loci, in the absence of species-specific PCR primers, to genetically identify the sires of 12 captive lowland gorillas (Gorilla gorilla gorilla) and 2 captive orangutans (Pongo pygmaeus pygmaeus andPongo p. abelii). Parentage assignments were confirmed by excluding all except a single potential sire for each offspring with the least two loci. Sire-offspring relationships were verified in 12 of the 14 cases, and reassigned in the case of two gorilla offspring. The orangutan paternity typing was supplemented by DNA fingerprinting. Additionally, five of the eight microsatellite loci, in conjunction with behavioral data, were used for a non-exhaustive set of paternity exclusions for five wild mountain gorillas (Gorilla g. beringei). The eight loci described in this study should be useful additions to the tools available for the study of genetics in the great apes.     

Behavioral and hormonal responses to the availability of forage material in Western lowland gorillas (Gorilla gorilla gorilla)

We investigated how forage material affects indicators of welfare in three male Western lowland gorillas (Gorilla gorilla gorilla) at the Detroit Zoo. In addition to their maintenance diet and enrichment foods, the gorillas generally received forage material four times a week. From this baseline, we systematically manipulated how much forage material the group received on a weekly basis, with either daily or bi (twice)‐weekly presentation of browse (mulberry, Morus sp.) or alfalfa hay. We collected behavioral data (60 hr per gorilla) and measured fecal glucocorticoid metabolites (FGM). Mixed models indicated that the presence of forage material significantly increased time feeding (F_2,351 = 9.58, p < 0.001), and decreased rates of noncontact aggression (F_2,351 = 3.69, p = 0.03), and regurgitation and reingestion (F_2,353 = 4.70, p = 0.01). Regurgitation and reingestion were never observed during the condition when forage material was provided daily. When forage material was provided, time spent feeding was similar across gorillas, compared to a disproportionately greater amount of time spent feeding by the dominant individual when forage material was absent. Providing forage material in addition to the regular diet likely created more opportunities for equitable feeding for the subordinate gorillas. FGM concentrations did not vary based on the presence or type of forage material available and, instead, likely reflected group social dynamics. In general, alfalfa and mulberry had similar impacts on behavior, indicating that alfalfa can be an adequate behavioral substitute during times when browse is less readily available for gorillas housed in seasonally variable climates.