2019
Review of Veterinary Intervention in Reproduction of Captive Western Lowland Gorillas (Gorilla gorilla gorilla) from 1996-2016
Erin Berlin, D.V.M., Mary Irene Thurber, D.V.M., Dipl. A.C.Z.M., and Nadine Lamberski, D.V.M., Dipl. A.C.Z.M., Dipl. E.C.Z.M. (Z. H. M.)
From the Western University of Health Sciences, 309 E Second Street, Pomona, CA 91766 (Berlin); University of California Davis School of Veterinary Medicine, 1 Shields Avenue, Davis, CA 95616, USA (Thurber); San Diego Zoo Global, 15500 San Pasqual Valley Rd, Escondido, CA 92027, USA (Thurber, Lamberski). Present address (Berlin): Omaha’s Henry Doorly Zoo and Aquarium, 3701 South 10th Street, Omaha, NE 68107; Present address (Thurber): Oakland Zoo, 9777 Golf Links Road, Oakland, CA 94605, USA.
In order to gain an understanding of the frequency of veterinary intervention during the periparturient period of western lowland gorillas (Gorilla gorilla gorilla) in captivity between 1996-2016, a survey was sent to institutions associated with the Association of Zoos and Aquariums’ (AZA) Gorilla Species Survival Plan® (SSP®). A total of 193 births were reported during the survey period, from 51/53 institutions. There were six incidences of prolonged labor (longer than six hours; 3%), six cases of cesarean section (3%), and three incidences of veterinary intervention that did not involve a cesarean section (2%). Fifty-one gorilla neonates (26%) were assist-reared (required intervention lasting longer than 24 hours). Out of 51 attempts to reintroduce neonates to dams or surrogates, 42 were accepted (82%), while 9 attempts (18%) were deemed failures. The age group with the highest rate of maternal or surrogate acceptance after reintroduction was between 6-12 months of age. Compared to data from a 1981 survey, the percentage of assist-reared gorillas decreased from 64% to 26%. Results show that veterinary intervention in the periparturient period is low, and there is a high rate of acceptance of neonates by either the dam or a surrogate after intervention. Advances in captive husbandry and veterinary knowledge have led to a reduced risk of veterinary intervention during gorilla parturition; however, the long-term effects on behavioral development of the neonate should be considered before removal of the infant from the dam for any period of time.
2016
Gorilla Population Histories
Linda Vigilant (Max Planck Institute for Evolutionary Anthropology) and Richard Bergl (North Carolina Zoological Park)
The specific aim of the project is to generate large amounts (> 50kb) of nuclear sequence data from western and eastern gorillas in order to improve the estimate of how long ago the two taxa diverged from one another, and estimate the amount, direction and duration of gene flow among these different populations. This project will also illuminate the extent to which the one-male mating system of gorillas has altered relative levels of genetic variation on the Y-chromosome, X-chromosome and autosomes relative to the levels found in chimpanzees and humans.
Thyroid Hormones, Thyroid Autoantibodies and Thyroid Histology in Gorillas with Non-Congenital Thyroid Dysfunction
Holly Aliesk (Cedars-Sinai Medical Center), Cynthia L. Courtney (Yerkes National Primate Research Center), Basil Rapoport (Cedars-Sinai Medical Center), and Sandra McLachlan (Cedars-Sinai Medical Center)
The great apes include, in addition to Homo, the genera Pongo (orangutans), Gorilla(gorillas), and Pan, the latter comprising two species, P. troglodytes (chimpanzees) and P. paniscus (bonobos). Adult-onset hypothyroidism was previously reported in 4 indiividual nonhuman great apes. However, there is scarce information on normal serum thyroid hormone levels and virtually no data for thyroid autoantibodies in these animals. Therefore, we examined thyroid hormone levels and TSH in all nonhuman great ape genera including adults, adolescents, and infants. Because hypothyroidism in humans is commonly the end result of thyroid autoimmunity, we also tested healthy and hypothyroid nonhuman great apes for antibodies to thryoglobulin (Tg), thryoid peroxidase (TPO), and the TSH receptor (TSHR). We established a thyroid hormone and TSH database for orangutans, gorillas, chimpanzees and bonobos (447 individuals). The most striking differences are the greatly reduced free-T4 and free-T3 levels in orangutans and gorillas vs chimpanzees and bonobos, and conversely, elevated TSH levles in gorillas vs Pan species. Antibodies to Tg and TPO were detected in only 2.6% of adult animals vs approximately 10% in humans. No animals with Tg, TPO, or TSHR thyroid antibodies exhibited thyroid dsyfunction. Conversely, hypothyroid nonhuman great apes lacked thyroid autoantibodies. Moreover, thyroid histology in necropsy tissues was similar in euthyroid and hypothyroid individuals, and lymphocytic infilitration was absent in 2 hypothyroid animals. In conclusion, free T4 and free T3 are lower in orangutans and gorillas vs chimpanzees and bonobos, the closest living human relatives. Moreover, thyroid autoantibodies are rare and hypothyroidism is unrelated to thyroid autoimmunity in nonhuman great apes.
2015
An Analysis of Wounding Rates in Gorilla Groups: A Multi-Institutional Study
Austin Leeds (Cleveland Metroparks Zoo), Dawn Boyer (Saint Louis Zoo), Kristen Lukas (Cleveland Metroparks Zoo), and Steve Ross (Lincoln Park Zoo)
Although the research conducted by Kuhar et al. (2008) is beginning to dispel the myth that bachelor troops are more volatile than mixed-sex groups, a perception still exists among zoo managers that it is more dangerous for gorillas to be housed in all-male groups than mixed-sex groups. There is some evidence that injuries can be stressful and, at times, life-threatening for gorillas and veterinary decisions regarding wound management can have serious consequences for group stability or individual wellbeing. The Gorilla SSP Veterinary Advisor Team is currently developing wound management guidelines to assist zoos in making decisions when wounding events occur. To gather systematic data on wounding in gorillas, we would like to apply the same methods employed by Ross et al. (in press) in documenting and analyzing wounding rates in chimpanzees. Our goals are to describe the incidence of wounding in the North American Gorilla SSP population and test the following null hypotheses for gorillas:
1. Age: There is no difference in the wounding rate of groups containing males in the young SB range (14-18) and groups containing older BB males (11-14) or older SB male (18+).
2. Sex: There is no difference in the wounding rate of male vs. female gorillas.
3. Group: There is no difference in the wounding rate of all-male vs. mixed-sex gorilla groups.
4. Social unrest: There is no difference in the wounding rate of stable social groups versus those experiencing social introductions within one year of the data collection period.
Alcohol Metabolism, Primate Evolution and Paleogenetics
Matthew Carrigan (Foundation for Applied Molecular Evolution) and Steven Benner (Foundation for Applied Molecular Evolution)
Alcohol dehydrogenase (ADH) and aldehyde dehydrogenase (AlDH) are two enzymes important in the detoxification of alcohols, including ethanol. We are a non-profit research foundation that has recently been funded by National Institute on Alcohol Abuse and Alcoholism (NIAAA) and the National Institute of Environmental Health Sciences (NIEHS), both part of the National Institutes of Health (NIH), to study the evolution of these proteins within the primate lineage. Ethanol was not always present in the environment, and it is therefore expected that evolutionary adaptation has occurred within these lineages since its introduction. We currently have the sequences of the ADH and AlDH genes for humans, Pan troglodytes, and Macaca mulatta (along with partial sequences for Pongo pygmaeus, Gorilla gorilla, and Papio hamadryas) through the NCBI genome database. We wish to expand upon the public database by sequencing the genes from as many other primates as possible, and to these ends, we seek the help of the larger zoo community. The exact species of the primates we use in our study is of less importance than obtaining genetic information from a wide diversity of primates, including representatives from each of the major evolutionary branches.
Admixture Between Historically Isolated Mitochondrial Lineages in Captive Western Gorillas:Recommendations for Future Management
Ivan Soto-Calderon (University of New Orleans, University of Antioquia), J. Larry Dew (Univesity of New Orleans), Richard Bergl (North Carolina Zoo), Michael Jensen-Seaman (Duquesne University), Nicola Anthony (University of New Orleans)
Although captive populations of western gorilla (Gorilla gorilla) have been maintained in the U.S. for over a century, little is known of the geographic origins and genetic composition of the current zoo population. Previous mitochondrial analyses have shown that natural populations of western gorillas exhibit substantial regional genetic structure. We combined pedigree records with mitochondrial sequence data from a subset of the U.S. captive gorillas to infer individual mitochondrial haplogroup affiliations, geographical origin of wild founders and assess the degree to which gorillas from historically isolated lineages have been inter-bred in captivity. The current U.S. captive population exhibits all major mitochondrial lineages within western lowland gorillas with levels of haplotype diversity comparable to that found in wild populations. However, the majority of crosses have occurred between individuals with different haplogroup affiliations. Although restricting crosses to individuals sharing the same haplogroup affiliation would preserve the phylogeographic structure present in the wild, without careful management such practice might also increase the risk of drift and inbreeding. Mitochondrial data are useful for tracking post-captive breeding history and document future admixture events. We recommend future releases to the wild take into account the mitochondrial affiliation and phylogeographic structure of wild populations.
2014
Nutrition of the captive western lowland gorilla (Gorilla gorilla gorilla): a dietary survey.
Katie Smith, PhD (University of Houston), Melissa Remis, PhD (Purdue Univeristy), Ellen Dierenfeld, PhD (Animal Nutrition Consultant)
The successful management of captive animals requires attention to multiple interconnected factors. One critical aspect of the daily life of a captive animal is the recommended and/or provisioned diet. This study focuses on the diets of zoo-housed gorillas. A national survey of diets among zoo-housed gorillas was conducted to examine diets being offered to captive gorillas in the United States and Canada. This survey serves as a follow-up to a 1995 dietary survey of zoo-housed gorillas and goes further to quantify nutritional profiles at responding institutions. Results are encouraging, as zoos have made clear improvements in dietary nutrient profiles offered over the past 15 years. However, we suggest that zoological and sanctuary institutions follow Gorilla Species Survival Plan (SSP) recommendations and work to continuously improve diets provided, which could improve gorillas' health and well-being.
2013
Thyroid Hormones, Thyroid Autoantibodies and Thyroid Histology in Gorillas with Non-Congenital Thyroid Dysfunction
Sandra McLachlan (Cedars-Sinai Medical Center)
Adult-onset hypothyroidism was previously reported in 4 individual nonhuman great apes. However, there is scarce information on normal serum thyroid hormone levels and virtually no data for thyroid autoantibodies in these animals. Therefore, we examined thyroid hormone levels and TSH in all nonhuman great ape genera including adults, adolescents, and infants. Because hypothyroidism in humans is commonly the end result of thyroid autoimmunity, we also tested healthy and hypothyroid nonhuman great apes for antibodies to thyroglobulin (Tg), thyroid peroxidase (TPO), and the TSH receptor (TSHR). We established a thyroid hormone and TSH database in orangutans, gorillas, chimpanzees, and bonobos (447 individuals). The most striking differences are the greatly reduced free-T4 and free-T3 levels in orangutans and gorillas vs chimpanzees and bonobos, and conversely, elevated TSH levels in gorillas vs Pan species. Antibodies to Tg and TPO were detected in only 2.6% of adult animals vs approximately 10% in humans. No animals with Tg, TPO, or TSHR antibodies exhibited thyroid dysfunction. Conversely, hypothyroid nonhuman great apes lacked thyroid autoantibodies. Moreover, thyroid histology in necropsy tissues was similar in euthyroid and hypothyroid individuals, and lymphocytic infiltration was absent in 2 hypothyroid animals. In conclusion, free T4 and free T3 are lower in orangutans and gorillas vs chimpanzees and bonobos, the closest living human relatives. Moreover, thyroid autoantibodies are rare and hypothyroidism is unrelated to thyroid autoimmunity in nonhuman great apes.
2011
Gorilla Contraception Survey
Sally Boutelle (AZA Wildlife Contraception Center)
The AZA Wildlife Contraception Center (WCC) is dedicated to bring contraceptive information for AZA animal populations, such as gorillas. As of April 2011, the Contraceptive Database holds over 26,500 records, 350 of which are for gorillas. With these data, analyses can be made on what products are effective, safe and reversible. The more information we gather, the more robust our data set. In 2010 it became apparent that more managers, veterinarians and keepers had questions specifically about brand name oral contraceptive pills and thus a full Gorilla Survey was created to address some of these inquiries. Birth control pills were the most commonly used form of contraception. Copulation is often observed while gorillas are contracepted and it is not common to see aggression increase after a female has been contracepted. Weight gain is common once a female gorilla is contracepted. For more information on this survey, please contact the AZA Wildlife Contraception Center.
Removal of Primate Chow from Gorilla Diets: The Impact on Behavior, Adiposity and Health
Elena Hoellein Less (Cleveland Metroparks Zoo), Richard Bergl (North Carolina Zoo), Shana Lavin (Lincoln Park Zoo), Pam Dennis (Cleveland Metroparks Zoo), Sylvia Atsalis (CRES, The Zoological Society of San Diego), Kristen Lukas (Cleveland Metroparks Zoo), and Christopher Kuhar (Cleveland Metroparks Zoo)
The proposed study examines the influence of typical captive diets on gorilla behavior, obesity and overall health. In particular, we propose that for captive western lowland gorillas, replacing chow and fruit with larger quantities of plant material will reduce undesirable behaviors, increase activity and reduce adiposity. To test this hypothesis, we will: measure the amount of time engaged in physical activity (i.e. foraging, climbing, running, etc...) and the rate of feeding-related undesirable behaviors according to the two different diet types; determine concentrations of serum hormones related to adiposity and biological markers of inflammation; examine stool volatile fatty acids; and apply body measurement indices of physical condition in a sample of captive western lowland gorillas.
Update: The authors are preparing this study for publication, and more results will be available soon.
Adiposity in Captive Gorillas: Variance in BMI, Diet, and Activity Levels
Elena Hoellein Less (Cleveland Metroparks Zoo), Pam Dennis (Cleveland Metroparks Zoo), Kristen Lukas (Cleveland Metroparks Zoo), Christopher Kuhar (Cleveland Metroparks Zoo), and Mary Ann Raghanti (Kent State University)
The proposed study examines the influence of diet and activity level on gorilla adiposity. In particular, we propose that for captive western lowland gorillas, those gorillas that are fed a diet more similar to their wild counterparts and/or spend a large percentage of time active will have lower adiposity as reflected by body mass index and hormone levels. To test these hypotheses, we propose to survey the diet composition and feeding protocol along with activity levels in all gorillas housed in Association of Zoo and Aquarium institutions. In conjunction with assessing diet and activity we will measure (1) serum hormone concentrations related to adiposity, (2) biological markers of inflammation and (3) body measurement indices.
Update: The authors are preparing this study for publication, and more results will be available soon.
A Longitudinal Assessment of Gorilla Personality
Tara Stoinski (Zoo Atlanta), Bonnie Perdue (Zoo Atlanta), Chris Kuhar (Cleveland Metroparks Zoo), Kristen Lukas (Cleveland Metroparks Zoo), and Ken Gold (American Humane Association)
The Gorilla Behavior Index (GBI) is a measure of gorilla personality (Gold, 1993). Seven years later in 2000, Kuhar et al. (2006) replicated these dimensions in a sample of 119 male gorillas. A subset of 79 individuals was sampled at both time points, and we recently analyzed the stability of personality across time in those individuals (Perdue et al., 2009). Although this was the first analysis to examine stability in personality traits in apes, it had two limitations. First, it only looked for stability over a relatively short portion of a gorilla's lifespan (7 years). Thus, data are still needed to examine stability across the lifespan, and, in particular, from subadult to adulthood. Gathering personality data again now permits an analysis over a 16 year period (1993-2009), thus ensuring that all individuals assessed as infants or juveniles in 1993 are now fully adult. Second, the analysis only included males as the 2000 personality data were only collected on males. Since the original dataset included females, we would now like to also gather data on females to look for sex differences in personality stability.
Update: Data analysis is ongoing and results will be available soon.
2010
Pan-African Sanctuary Alliance (PASA) Ape Modeling Project
Lisa Faust (Lincoln Park Zoo) and Ben Beck (Great Ape Trust)
This project's focus is on modeling the demography of representative great ape sanctuary populations using the captive population studbook to project the amount of space needed to house existing sanctuary specimens and accommodate new specimens being confiscated. The model should provide a valuable example of the time and resources required to maintain confiscated ape populations throughout their natural lifespan, giving sanctuaries a better understanding of the nature and extent of their commitment.
Update: Reports on gorilla dynamics were sent directly to sanctuary managers. Because more PASA sanctuaries contain chimpanzees, work on only chimpanzees was published:
Faust, LJ., Cress, D., Farmer, KH., Ross, SR., and Beck, BB. 2011. Predicting capacity demand on sanctuaries for African chimpanzees (Pan troglodytes). International Journal of Primatology: Published online 8 Mar 2011.
2009
Cataloging Blood Types for SSP Populations of Great Apes
Kathryn Gamble (Lincoln Park Zoo) and Jill Moyse (Lincoln Park Zoo)
In humans and domestic mammals, blood typing plays an important role
in providing excellent medical care in critical care situations. It has been repeatedly demonstrated in the literature that humans and great apes have conserved identities within the standard blood typing categories of A-B-O and D(Rh factor). Development of simple table-top laboratories techniques to identify these most basic of blood groups in human patients may be applied to similar benefit in the great ape species.
Update: This study is complete and authors are currently preparing the study for publication. When available, we will post a summary of results.
Captive Great Apes and Their Interactions with Local Wildlife
Update: The authors wish to thank all zoos which participated in this study. The full results are published in:
Ross SR, Holmes AN, Lonsdorf EV. 2009. Interactions Between Zoo-Housed Great Apes and Local Wildlife. American Journal of Primatology 71(6):458-465.
Steve Ross (Lincoln Park Zoo) and Elizabeth Lonsdorf (Lincoln Park Zoo)
Although there are published reports of wild chimpanzees, bonobos, and orangutans hunting and consuming vertebrate prey, data pertaining to captive apes remain sparse. In this survey-based study, we evaluate the prevalence and nature of interactions between captive great apes and various indigenous wildlife species that range into their enclosures in North America. Our hypotheses were threefold: (a) facilities housing chimpanzees will report the most frequent and most aggressive interactions with local wildlife; (b) facilities housing orangutans and bonobos will report intermediate frequencies of these interactions with low levels of aggression and killing; and (c) facilities housing gorillas will report the lowest frequency of interactions and no reports of killing local wildlife. Chimpanzees and bonobos demonstrated the most aggressive behavior toward wildlife, which matched our predictions for chimpanzees, but not bonobos. This fits well with expectations for chimpanzees based on their natural history of hunting and consuming prey in wild settings, and also supports new field data on bonobos. Captive gorillas and orangutans were reported to be much less likely to chase, catch and kill wildlife than chimpanzees and bonobos. Gorillas were the least likely to engage in aggressive interactions with local wildlife, matching our predictions based on natural history. However unlike wild gorillas, captive gorillas were reported to kill (and in one case, eat) local wildlife. These results suggest that some behavioral patterns seen in captive groups of apes may be useful for modeling corresponding activities in the wild that may not be as easily observed and quantified. Furthermore, the data highlight the potential for disease transmission in some captive settings, and we outline the associated implications for ape health and safety.
2008
Assessing the Prevalence and Characteristics of Hair Plucking Behavior in Captive Western Lowland Gorillas (Gorilla gorilla gorilla)
Elena Less (Cleveland Metroparks Zoo) and Kristen Lukas (Cleveland Metroparks Zoo)
This study's focus is on describing hair plucking behavior in captive gorillas, as well as evaluating risk factors that may predispose gorillas to exhibit this behavior. The results will be used to inform captive management decisions on ameliorating this behavior in the captive population.
Update: This survey is complete and data is currently being analyzed by the PI. The authors wish to thank the 38 zoos who participated.
2007
Detection of SIVgor Infection in Captive Gorillas
Brandon Keele (University of Alabama) and Beatrice Hahn (University of Alabama)
There was recently reported in Nature evidence of a naturally occurring simian immunodeficiency virus infection in wild gorillas (G. g. gorilla) which was designated as SIVgor. The objective of this study is to determine if any captive gorillas are likewise infected. This study requests either plasma or fecal samples for each captive gorilla.
Update: No captive gorillas tested positive for SIVgor infection.
2005
Assisted Reproduction Using Sex-Sorted Sperm: A Management Strategy for Captive Gorillas
Naida Loskutoff (Henry Doorly Zoo)
In light of the precarious state of gorillas in their natural habitats, the American Zoo and Aquarium Association (AZA) Gorilla Species Survival Plan (SSP) proposes the application of assisted reproductive technology as a means for allowing the genetic contributions of these animals to increase the likelihood of long-term genetic health and survival of the species. The aim of this research is to use the most recent advances in human assisted reproductive technologies as a model to develop methodology for producing female offspring from genetically underrepresented individuals in the Gorilla SSP. This study requests sperm samples from male gorillas and oocytes for female gorillas.
Update: We adapted flow cytometry technology for high-purity sorting of X chromosome-bearing spermatozoa in the western lowland gorilla (Gorilla gorilla gorilla). Our objectives were to develop methodologies for liquid storage of semen prior to sorting, sorting of liquid-stored and frozen-thawed spermatozoa, and assessment of sorting accuracy. In study 1, the in vitro sperm characteristics of gorilla ejaculates from one male were unchanged (P>0.05) after 8 hr of liquid storage at 15°C in a non-egg yolk diluent (HEPES-buffered modified Tyrode's medium). In study 2, we examined the efficacy of sorting fresh and frozen-thawed spermatozoa using human spermatozoa as a model for gorilla spermatozoa. Ejaculates from one male were split into fresh and frozen aliquots. X-enriched samples derived from both fresh and frozen-thawed human semen were of high purity, as determined by fluorescence in situ hybridization (FISH; 90.7%±2.3%, overall), and contained a high proportion of morphologically normal spermatozoa (86.0%±1.0%, overall). In study 3, we processed liquid-stored semen from two gorillas for sorting using a modification of methods for human spermatozoa. The sort rate for enrichment of X-bearing spermatozoa was 7.3±2.5 spermatozoa per second. The X-enriched samples were of high purity (single-sperm PCR: 83.7%) and normal morphology (79.0%±3.9%). In study 4 we examined frozen-thawed gorilla semen, and the sort rate (8.3±2.9 X-bearing sperm/sec), purity (89.7%), and normal morphology (81.4%±3.4%) were comparable to those of liquid-stored semen. Depending on the male and the type of sample used (fresh or frozen-thawed), 0.8-2.2% of gorilla spermatozoa in the processed ejaculate were present in the X-enriched sample. These results demonstrate that fresh or frozen-thawed gorilla spermatozoa can be flow cytometrically sorted into samples enriched for X-bearing spermatozoa.
Published in:
O'Brien, JK., Losuktoff, NM., et al. 2005. Flow cytometric sorting of fresh and frozen-thawed spermatozoa in the western lowland gorilla (Gorilla gorilla gorilla). American Journal of Primatology 66 (4): 297-315.