Food transfers in immature wild western lowland gorillas (Gorilla gorilla gorilla)
AffiliationUniversity of Chester; Nouabalé-Ndoki National Park
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AbstractThis article discusses how the transfer of food items between primates serves an informative purpose in addition to supplementing the diet of immature individuals. Food transfers amongst immature western lowland gorillas (Gorilla gorilla gorilla), at Mbeli Bai, Republic of Congo weew observed.
CitationNowell, A. A., & Fletcher, A. W. (2006). Food transfers in immature wild western lowland gorillas (Gorilla gorilla gorilla). Primates, 47(4), 294-299. https://doi.org/10.1007/s10329-006-0181-0
DescriptionThis article is not available through ChesterRep.
SponsorsThis article was submitted to the RAE2008 for the University of Chester - Allied Health Professions and Studies.
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Behavioural development in wild Western lowland gorillas (gorilla gorilla gorilla)Fletcher, Alison W.; Nowell, Angela A. (University of Liverpool (University of Chester), 2005-02)Behavioural development has received little attention in primates, despite having important influences on infant mortality, interbirth intervals, and therefore, growth of populations. Gorillas have long developmental periods, exhibit strong maternal bonds and integrate into intricate social systems, making them an ideal species in which to investigate non-human primate development. Gorillas exist across a range of habitats, and differences in behaviour, both within and between species reflect socioecological differences, for example, in the availability and distribution of food. Consequently, by using gorillas as a model, opportunities also exist to investigate environmental constraints on the development of independence. This study provides the first detailed analysis, with reference to ecological factors, of the development of behavioural skills and relationships in wild western lowland gorillas (Gorilla gorilla gorilla). Behavioural development of western lowland gorillas is then compared with published accounts of development in mountain gorillas (Gorilla beringei beringei) to determine the extent to which differing ecology influences behaviour. The study was conducted at Mbeli Bai in the Republic of Congo, a large, marshy clearing, visited by gorillas predominantly for feeding purposes. Data were collected using scan, focal, all-occurrence and ad libitum sampling methods from 58 gorillas below 8 years of age. Spatial relationships, suckling, and the nature of interactions involving immature individuals were analysed. The distribution of time between different behaviours by immatures, and the development of independent feeding and travelling behaviour was also investigated, and all were tested for differences as a result of immature age, sex and social group, or the mother's parity. Towards the end of infancy, individuals showed competent feeding behaviour in the bai. However, western lowland gorillas were not weaned until the juvenile period, and until this time, close association was common between mothers and offspring. With increasing independence from the mother there was limited investment in relationships with other individuals, and instead, a greater emphasis was placed on developing skills through play, alloparenting and agonistic interactions. When results were compared with those of mountain gorillas, there was evidence of increased investment in relationships, particularly with the silverback, by immature mountain gorillas, which was assumed to reflect lower rates of natal dispersal by mountain gorillas, and the greater likelihood that relationships with individuals in the natal group could prove useful in the future. Suckling and close proximity to the mother continued until later ages in western lowland gorillas, resulting in clear differences between them mountain gorillas in the duration of investment by mothers. More frugivorous western lowland gorillas required increased levels of investment by the mother before independence could be achieved, demonstrating the effect that resource availability can have on behavioural development in species where resources are widely and unpredictably dispersed.
Mirror self-recognition in gorillas (Gorilla gorilla gorilla): A review and evaluation of mark test replications and variantsMurray, Lindsay; Anderson, James R.; Gallup, Gordon G.; University of Chester; Kyoto University Graduate School of Letters; University at Albany, State University of New York (Springer, 2022-01-07)Mirror self-recognition (MSR), widely regarded as an indicator of self-awareness, has not been demonstrated consistently in gorillas. We aimed to examine this issue by setting out a method to evaluate gorilla self-recognition studies that is objective, quantifiable, and easy to replicate. Using Suarez and Gallup’s (1981) study as a reference point, we drew up a list of 15 methodological criteria and assigned scores to all published studies of gorilla MSR for both methodology and outcomes. Key features of studies finding both mark-directed and spontaneous self-directed responses included visually inaccessible marks, controls for tactile and olfactory cues, subjects who were at least five years old, and clearly distinguishing between responses in front of versus away from the mirror. Additional important criteria include videotaping the tests, having more than one subject, subjects with adequate social rearing, reporting post-marking observations with mirror absent, and giving mirror exposure in a social versus individual setting. Our prediction that MSR studies would obtain progressively higher scores as procedures and behavioural coding practices improved over time was supported for methods, but not for outcomes. These findings illustrate that methodological rigour does not guarantee stronger evidence of self-recognition in gorillas; methodological differences alone do not explain the inconsistent evidence for MSR in gorillas. By implication, it might be suggested that, in general, gorillas do not show compelling evidence of MSR. We advocate that future MSR studies incorporate the same criteria to optimize the quality of attempts to clarify the self-recognition abilities of gorillas as well as other species.
Development of independence from the mother in Gorilla gorilla gorillaNowell, Angela A.; Fletcher, Alison W.; University of Chester; Nouabalé-Ndoki National Park (Springer, 2007-05-02)This article investigates the development of independence in a population of wild western gorillas (Gorilla gorilla gorilla) at Mbeli Bai, Nouabalé-Ndoki National Park, Republic of Congo.