Female Western Lowland Gorilla Research Articles

Infant survival in western lowland gorillas after voluntary dispersal by pregnant females

In many social species, after the alpha male has been replaced or the group disintegrates, a female’s infant is at risk of infanticide by a male. Female gorillas have developed the rare strategy of secondary dispersal in which they transfer between reproductive groups during the limited time period between weaning an infant and conceiving the next one (voluntary dispersal). By doing so they leave a weaker silverback near the end of his tenure and join a stronger silverback at an earlier stage of his own tenure, thereby mitigating the risk of infanticide if the former dies. If females are pregnant or have unweaned offspring when the only male in the group dies, their offspring are vulnerable to infanticide by the new silverback that they join (via involuntary dispersal). In the few known cases of female gorillas transferring when pregnant (mainly after group disintegration), their offspring were killed. We report here on three adult females that transferred voluntarily while pregnant multiple times between two groups yet their offspring were not killed by the new group’s silverback. The gorillas were observed from 1995 to 2015 at the Mbeli Bai research site in northern Republic of the Congo. The females gave birth 5–6 months (gestation period 8.5 months) after their last transfer. To our knowledge, these observations are the first to show that wild female western lowland gorillas can transfer voluntarily while pregnant without incurring infanticide by a new silverback. These observations highlight the behavioural plasticity shown by female gorillas in response to sexual coercion by males.

Attached beyond death: Wild female western lowland gorilla (Gorilla gorilla gorilla) carries and cares for mummified infant

Attached beyond death: Wild female western lowland gorilla (<i>Gorilla gorilla gorilla</i>) carries and cares for mummified infant

Management of respiratory complications in a western lowland gorilla (Gorilla gorilla gorilla) born by cesarean section.

A female western lowland gorilla (Gorilla gorilla gorilla) infant was delivered by cesarean section (C-section) to an 18-year-old primiparous dam after prolonged labor. The infant required resuscitation at birth and was hospitalized for management of pneumonia and associated respiratory distress secondary to the aspiration of meconium-stained amniotic fluid. The infant received nine days of intensive care with respiratory support, antibiotics, intravenous fluid therapy, anti-inflammatory drugs, bronchodilators, and chest physiotherapy. Respiratory support included nasal continuous positive airway pressure (CPAP), and supplemental oxygen. Complications included right lung atelectasis secondary to bronchial obstruction and pneumonia. Following the resolution of pneumonia, visual reintroductions with the troop were initiated. The dam was given a medical lactation supplement (metoclopramide) and her mammary glands were stimulated to increase milk production. After several days of visual and olfactory introductions, the infant was successfully physically reintroduced to her dam at 12 days of age; the dam showed appropriate maternal response and nursing of the infant. The infant had appropriate growth and development, and 4 years later, has no evidence of negative side effects of neonatal respiratory disease. This is the first reported case of management of neonatal gorilla respiratory disease associated with a C-section, with successful reintroduction to the family group after hospitalization.

The Effect of Positive Reinforcement Training on an Adult Female Western Lowland Gorilla’s (Gorilla gorilla gorilla) Rate of Abnormal and Aggressive Behavior

The Effect of Positive Reinforcement Training on an Adult Female Western Lowland Gorilla’s (Gorilla gorilla gorilla) Rate of Abnormal and Aggressive Behavior

A Study on Diagnosis of the Fertility of one Aged Female Gorilla by using the Fecal Sex Hormone Metabolites

The aim of this study was to diagnose the fertility of a female western lowland gorilla kept in Seoul Zoo, in accordance with age by analyzing the fecal sex hormone metabolites. The study was conducted in two period of times, when the animal was from 35 to 37 years old and when the animal was from 40 to 42 years old. Non-invasive method by using fecal samples was used for safe and efficient fertility diagnosis. We collected the feces from the enclosure at least three times a week. Then 17β-estradiol and progesterone, which are fecal sex hormone metabolites, were measured by time-resolved fluoro-immunoassay to compare the menstruation cycle and the annual reproductive cycle. For the duration of the primary study (when the animal was 35~37 years old), irregular menstruation and high concentrations of estradiol and progesterone were observed. However, menstruation was hardly observed and the concentrations of both hormones were statistically very low in the period of secondary study (when the animal was 40~42 years old). This observed phenomenon in our study was very comparable to menopause in adult women; therefore, it was confirmed that our female gorilla has reached menopause because of the natural aging, as they become older.

Evaluating the physiological and behavioral response of a male and female gorilla (Gorilla gorilla gorilla) during an introduction.

Prolonged stress responses can lead to infertility and death; therefore monitoring respective indicators like stress-related hormones and behaviors is an important tool in ensuring the health and well-being among zoo-housed animal populations. Changes in social structure, such as the introduction of a new conspecific, can be a source of stress. In April 2010, a sexually mature female western lowland gorilla (Gorilla gorilla gorilla) was brought to Lincoln Park Zoo (LPZ; Chicago, IL) from the Chicago Zoological Park (Brookfield, IL) for a breeding recommendation from the Gorilla Species Survival Plan. Fecal glucocorticoid metabolites (FGMs) were monitored in two gorillas prior to, during and immediately following the social introduction. Reproduction events, such ovarian cyclicity and pregnancy, were monitored using behavior and fecal progestagen metabolite (FPM; female) and fecal androgen metabolite (FAM; male) analyses. Mean (± standard error) FGM concentrations for the male were elevated (P = 0.002) during the introduction (20.61 ± 0.83 ng/g) compared to the pre- and post-introduction phases (11.31 ± 0.48 ng/g and 12.42 ± 0.65 ng/g, respectively). For the female, mean FGM concentrations were lower (P < 0.001) during the post-introduction (17.91 ± 1.07 ng/g) than during the pre- and introduction phases (30.50 ± 3.42 and 27.38 ± 1.51 ng/g, respectively). The female maintained normal FPM cyclicity throughout the study and became pregnant in the post-introduction phase. These results suggest the importance of both behavioral and physiological monitoring of zoo animals and demonstrate the potential stress that can occur during social introductions. Zoo Biol. 33:394-402, 2014. © 2014 Wiley Periodicals Inc.

RETROPERITONEAL ABSCESSES IN TWO WESTERN LOWLAND GORILLAS (GORILLA GORILLA GORILLA)

This report describes two cases of retroperitoneal abscesses in female western lowland gorillas (Gorilla gorilla gorilla). Clinical symptoms included perivulvar discharge, lameness, hindlimb paresis, and general malaise. Retroperitoneal abscesses should be considered as part of a complete differential list in female gorillas with similar clinical signs.

UNUSUAL TURNER SYNDROME MOSAIC WITH A TRIPLE X CELL LINE (47,X/49,XXX) IN A WESTERN LOWLAND GORILLA (GORILLA GORILLA GORILLA)

A 29-yr-old female western lowland gorilla (Gorilla gorilla gorilla) was evaluated for low fertility and a midterm abortion. Laboratory testing included karyotyping, which revealed an unusual mosaicism for Turner syndrome with Triple X (47,X/49,XXX). This appears to be the first report of Turner syndrome in a great ape. In humans, Turner syndrome occurs in approximately 1 in 3,000 females, with half of those monosomic for the X chromosome. A small proportion is mosaic for a triple X cell line (3-4%). In humans, Turner syndrome is associated with characteristic phenotype including short stature, obesity, a broad chest with widely spaced nipples, webbing of the neck, and anteverted ears. This individual gorilla is significantly shorter in stature than conspecifics and is obese despite normal caloric intake. Individuals with Turner syndrome should also be screened for common health issues, including congenital heart defects, obesity, kidney abnormalities, hypertension, hypothyroidism, and diabetes mellitus. Animals with decreased fertility, multiple miscarriages, fetal losses, unusual phenotypes, or a combination of these symptoms should be evaluated for genetic abnormalities.

Hemorrhagic colitis associated withSalmonella entericaserotype Infantis infection in a captive western lowland gorilla (Gorilla gorilla gorilla) inBrazil

Enteric diseases are among the most common causes of morbidity and mortality in gorillas, and it is often caused by bacteria. A thirteen-year-old captive female western lowland gorilla (Gorilla gorilla gorilla) developed hemorrhagic diarrhea. Despite the treatment, the animal died 7 days after the onset of clinical signs. The animal was submitted to a thorough pathological and microbiological evaluation. Pathologic examination revealed a severe acute hemorrhagic colitis, neutrophilic splenitis, glomerulitis, and interstitial pneumonia. Salmonella enterica serotype Infantis was isolated from a mesenteric lymph node. A diagnosis of hemorrhagic colitis associated with Salmonella enterica serotype Infantis was established.

Alzheimer's disease pathology in the neocortex and hippocampus of the western lowland gorilla (Gorilla gorilla gorilla)

The two major histopathologic hallmarks of Alzheimer's disease (AD) are amyloid beta protein (Aβ) plaques and neurofibrillary tangles (NFT). Aβ pathology is a common feature in the aged nonhuman primate brain, whereas NFT are found almost exclusively in humans. Few studies have examined AD-related pathology in great apes, which are the closest phylogenetic relatives of humans. In the present study, we examined Aβ and tau-like lesions in the neocortex and hippocampus of aged male and female western lowland gorillas using immunohistochemistry and histochemistry. Analysis revealed an age-related increase in Aβ-immunoreactive plaques and vasculature in the gorilla brain. Aβ plaques were more abundant in the neocortex and hippocampus of females, whereas Aβ-positive blood vessels were more widespread in male gorillas. Plaques were also Aβ40-, Aβ42-, and Aβ oligomer-immunoreactive, but only weakly thioflavine S- or 6-CN-PiB-positive in both sexes, indicative of the less fibrillar (diffuse) nature of Aβ plaques in gorillas. Although phosphorylated neurofilament immunostaining revealed a few dystrophic neurites and neurons, choline acetyltransferase-immunoreactive fibers were not dystrophic. Neurons stained for the tau marker Alz50 were found in the neocortex and hippocampus of gorillas at all ages. Occasional Alz50-, MC1-, and AT8-immunoreactive astrocyte and oligodendrocyte coiled bodies and neuritic clusters were seen in the neocortex and hippocampus of the oldest gorillas. This study demonstrates the spontaneous presence of both Aβ plaques and tau-like lesions in the neocortex and hippocampus in old male and female western lowland gorillas, placing this species at relevance in the context of AD research.

Suspected macular degeneration in a captive western lowland gorilla (gorilla gorilla gorilla)

The case of a 31-year-old captive female Western lowland gorilla (Gorilla gorilla gorilla) with decreased near vision but good distance vision is presented. Examination of the fundus revealed drusen-like bodies in the macula presumably because of an age-related macular degeneration (AMD).

Gorilla gorilla gorilla

The gorilla genome reveals that genetic similarities among humans and the apes are more complex than expected, and allows a fresh assessment of the evolutionary mechanisms that led to the primate species seen today. See Article p.169 The genome of the gorilla has been sequenced, making it possible to compare the DNA of the four surviving hominid genera: human, chimpanzee, gorilla and orang-utan. The data — mainly from a female western lowland gorilla named Kamilah, but also from other gorillas representing both the western lowland and eastern lowland sub-species — imply that in almost one-third of its genome, the gorilla is closer to the human or chimpanzee than the human and chimp are to each other. Around 500 genes show accelerated evolution in gorilla, human and chimpanzee lineages, and there is evidence for parallel acceleration, particularly in genes associated with hearing. On the basis of genetic and fossil evidence, the authors suggest that the human–chimpanzee and human–chimpanzee–gorilla speciation events occurred at around 6 million and 10 million years ago respectively, whereas the two gorilla species diverged around 1.75 million years ago.

Fatal Balamuthia mandrillaris infection in a gorilla - first case of balamuthiasis in Germany

A 12-year-old female western lowland gorilla died in a zoological garden in Germany after exhibiting general neurological signs. Balamuthia mandrillaris was identified as causative agent by indirect immunofluorescent staining of brain sections and confirmed by PCR and respective sequencing. The animal suffered from a chronic progressive necrotizing amebic meningoencephalitis. This is the first case of Balamuthia amebic encephalitis in Germany.

Debilitating Clinical Disease in a Wild-Born Captive Western Lowland Gorilla (Gorilla gorilla gorilla) Co-Infected with Varicella Zoster Virus (VZV) and Simian T-Lymphotropic Virus (STLV)

A wild-born, 34-yr-old female western lowland gorilla (Gorilla gorilla gorilla) was transferred between zoologic collections in the United Kingdom. Adjustment to its new environment was difficult and a series of health problems ensued. Progressive severe illness of multiple etiologies, and a failure to respond to multiple therapies, led to its euthanasia 5 mo later. Disease processes included severe thoracic and axillary cutaneous ulceration of T2-3 dermatome distribution, gastroenteritis, ulcerative stomatitis, emaciation, hind limb weakness or paresis, and decubitus ulcers of the ankles and elbows. Ante- and postmortem infectious disease screening revealed that this animal was not infected with Mycobacterium tuberculosis, simian varicella virus (SVV), simian immunodeficiency virus (SIV), or hepatitis B virus; but was infected with varicella-zoster virus (VZV) and simian T-lymphotropic virus (STLV). It is hypothesized that recrudescence of VZV and other disease processes described were associated with chronic STLV infection and the end of a characteristically long incubation period.

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

AbstractBackground 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.

Dientamoeba fragilis: Initial Evidence of Pathogenicity in the Western Lowland Gorilla (Gorilla gorilla gorilla)

A 7-yr-old female western lowland gorilla (Gorilla gorilla gorilla) shared an enclosure with 10 other gorillas at the Limbe Wildlife Centre (LWC), a wildlife rehabilitation centre in Cameroon. The gorilla had been living at the LWC for more than 6 yr prior to the exhibition of irritable bowel syndrome (IBS)-like clinical signs. The gorilla improved dramatically after metronidazole therapy. The report suggests that metronidazole was effective because it eliminated the protozoa, Dientamoeba fragilis. Dientamoeba fragilis should be considered on the differential diagnosis list of any captive gorilla with IBS-like symptoms.

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.

Sequential list-learning by an adolescent lowland gorilla (Gorilla gorilla gorilla) using an infrared touchframe apparatus

The ability to appropriately sequence a list of discrete items is an important facet in performing routine cognitive tasks and may play a significant role in the acquisition of early communication skills. Though the serial learning abilities of some species, such as chimpanzees and rhesus macaques are well documented, there is virtually no information on the extent of these skills with gorillas. In this study, a young female western lowland gorilla has demonstrated the ability to learn a list of seven Arabic numerals by selecting them on a monitor behind an infrared touchframe. As list length increased (from three to seven), Rollie required fewer trials to reach the criterion, suggesting an acquisition of skills associated with serial learning. Rollie was most likely to correctly select the first item in the sequence and least likely to select the penultimate item in the sequence. Her performance suggests serial learning abilities in the range of other non-verbal species and provides preliminary evidence that supports the assertion that gorillas can succeed at this form of serial learning task.

Cervical necrotizing fasciitis and myositis in a western lowland gorilla (Gorilla gorilla gorilla)

A 39-yr-old wild-caught, female western lowland gorilla (Gorilla gorilla gorilla) died during an immobilization to assess swelling and apparent pain of the cervical region. Necropsy revealed a fistulous tract containing plant material in the oropharynx, above the soft palate, communicating with a left-sided cervical necrotizing fasciitis and myositis. Alpha-hemolytic Streptococcus and Prevotella sp. were isolated from the cervical lesion. This is a report of cervical necrotizing fasciitis in a western lowland gorilla.

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.