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Judson K, Sanz C, Ebombi TF, Massamba JM, Teberd P, Abea G, Mbebouti G, Matoumona JKB, Nkoussou EG, Zambarda A, Brogan S, Stephens C, Morgan D. Socioecological factors influencing intraspecific variation in ranging dynamics of western lowland gorillas (Gorilla gorilla gorilla) in Ndoki Forest. Am J Primatol 2024; 86:e23586. [PMID: 38151775 DOI: 10.1002/ajp.23586] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2023] [Revised: 11/13/2023] [Accepted: 12/10/2023] [Indexed: 12/29/2023]
Abstract
Ranging dynamics are physical and behavioral representations of how different socioecological factors affect an organism's spatial decisions and space use strategies. Western lowland gorillas (Gorilla gorilla gorilla) are a model species to investigate the drivers of spatial dynamics based on both the natural variation in socioecological factors within the species and compared with their mountain gorilla counterparts. In this study, we evaluate the influences of resource seasonality and social dynamics on variation in home range size, utilization, and intergroup overlap among multiple gorilla groups over an 8-year study period in the northern Republic of Congo. This study shows that western lowland gorillas can have small home ranges comparable to mountain gorillas, rather than universally larger home ranges as previously supposed, and that home ranges are stable through time. The largest source of variation in space use was the degree of intergroup home range overlap. The study groups did not demonstrate intraspecific variation in range size nor changes in intergroup overlap with respect to seasonality of fruit resources, but all groups demonstrated expansion of monthly range and core area with group size, matching predictions of intragroup feeding competition. These findings highlight the potential impact of intergroup relationships on space use and prompt further research on the role of social dynamics in ranging strategies. In this study, we reveal a greater degree of variability and flexibility in gorilla ranging behavior than previously realized which is relevant to improving comparative studies and informing conservation strategies on behalf of these endangered primates.
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Affiliation(s)
- Kathryn Judson
- Department of Anthropology, Washington University in Saint Louis, Saint Louis, Missouri, USA
| | - Crickette Sanz
- Department of Anthropology, Washington University in Saint Louis, Saint Louis, Missouri, USA
- Wildlife Conservation Society, Congo Program, Brazzaville, Republic of Congo
| | | | - Jean Marie Massamba
- Wildlife Conservation Society, Congo Program, Brazzaville, Republic of Congo
| | - Prospère Teberd
- Wildlife Conservation Society, Congo Program, Brazzaville, Republic of Congo
| | - Gaston Abea
- Wildlife Conservation Society, Congo Program, Brazzaville, Republic of Congo
| | - Gaeton Mbebouti
- Wildlife Conservation Society, Congo Program, Brazzaville, Republic of Congo
| | | | | | - Alice Zambarda
- Wildlife Conservation Society, Congo Program, Brazzaville, Republic of Congo
| | - Sean Brogan
- Wildlife Conservation Society, Congo Program, Brazzaville, Republic of Congo
| | - Colleen Stephens
- Department of Anthropology, Washington University in Saint Louis, Saint Louis, Missouri, USA
| | - David Morgan
- Fisher Center for the Study and Conservation of Apes, Chicago, Illinois, USA
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Auger C, Cipolletta C, Todd A, Fuh T, Sotto-Mayor A, Pouydebat E, Masi S. Feeling a bit peckish: Seasonal and opportunistic insectivory for wild gorillas. AMERICAN JOURNAL OF BIOLOGICAL ANTHROPOLOGY 2023; 182:210-223. [PMID: 37483018 DOI: 10.1002/ajpa.24811] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/31/2023] [Revised: 06/04/2023] [Accepted: 06/24/2023] [Indexed: 07/25/2023]
Abstract
OBJECTIVES Insectivory likely contributed to survival of early humans in diverse conditions and influenced human cognitive evolution through the need to develop harvesting tools. In living primates, insectivory is a widespread behavior and frequently seasonal, although previous studies do not always agree on reasons behind this. Since western gorillas (Gorilla gorilla) diet is largely affected by seasonal variation in fruit availability, we aimed to test three non-mutually exclusive hypotheses (habitat use, frugivory and rainfall) to explain seasonality in termite feeding across age/sex classes in three habituated groups (Nindividuals = 27) in Central Africa. MATERIALS AND METHODS We used 4 years of ranging, scan and continuous focal sampling records of gorillas (Nranging days = 883, Nscans = 12,384; Nhours = 891) in addition to 116 transects recording vegetation and termite mound distribution. RESULTS Depending on the age/sex classes, we found support for all three hypotheses. Time spent in termite-rich vegetation positively impacted termite consumption in all age/sex classes, but subadults. Lengthier travels increased termite feeding in females but decreased it in subadults. Frugivory decreased termite consumption in adults. Daily rainfall had a positive effect on termite feeding and foraging in silverbacks and juveniles, but a negative effect in subadults. For females, rainfall had a positive effect on termite feeding, but a negative effect for termite foraging. DISCUSSION In great apes, seasonal insectivory seems to be multifactorial and primarily opportunistic with important differences among age/sex classes. While insectivory has potentials to be traditional, it likely played a crucial role during primate evolution (including ours), allowing diet flexibility in changing environments.
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Affiliation(s)
- Claire Auger
- Éco-Anthropologie, Museum National d'Histoire Naturelle, Centre National de la Recherche Scientifique: UMR7206, Paris, France
- Mécanismes Adaptatifs et Evolution, Museum National d'Histoire Naturelle, Centre National de la Recherche Scientifique: UMR7179, Paris, France
| | - Chloé Cipolletta
- Dzanga-Sangha Protected Areas, World Wide Fund for Nature, Bangui, Central African Republic
| | - Angelique Todd
- Dzanga-Sangha Protected Areas, World Wide Fund for Nature, Bangui, Central African Republic
| | - Terence Fuh
- Dzanga-Sangha Protected Areas, World Wide Fund for Nature, Bangui, Central African Republic
| | - Andrea Sotto-Mayor
- Éco-Anthropologie, Museum National d'Histoire Naturelle, Centre National de la Recherche Scientifique: UMR7206, Paris, France
| | - Emmanuelle Pouydebat
- Mécanismes Adaptatifs et Evolution, Museum National d'Histoire Naturelle, Centre National de la Recherche Scientifique: UMR7179, Paris, France
| | - Shelly Masi
- Éco-Anthropologie, Museum National d'Histoire Naturelle, Centre National de la Recherche Scientifique: UMR7206, Paris, France
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Robbins MM, Akantorana M, Arinaitwe J, Breuer T, Manguette M, McFarlin S, Meder A, Parnell R, Richardson JL, Stephan C, Stokes EJ, Stoinski TS, Vecellio V, Robbins AM. Comparative life history patterns of female gorillas. AMERICAN JOURNAL OF BIOLOGICAL ANTHROPOLOGY 2023; 181:564-574. [PMID: 37345324 DOI: 10.1002/ajpa.24792] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/20/2022] [Revised: 03/16/2023] [Accepted: 05/24/2023] [Indexed: 06/23/2023]
Abstract
OBJECTIVES Several theories have been proposed to explain the impact of ecological conditions on differences in life history variables within and between species. Here we compare female life history parameters of one western lowland gorilla population (Gorilla gorilla gorilla) and two mountain gorilla populations (Gorilla beringei beringei). MATERIALS AND METHODS We compared the age of natal dispersal, age of first birth, interbirth interval, and birth rates using long-term demographic datasets from Mbeli Bai (western gorillas), Bwindi Impenetrable National Park and the Virunga Massif (mountain gorillas). RESULTS The Mbeli western gorillas had the latest age at first birth, longest interbirth interval, and slowest surviving birth rate compared to the Virunga mountain gorillas. Bwindi mountain gorillas were intermediate in their life history patterns. DISCUSSION These patterns are consistent with differences in feeding ecology across sites. However, it is not possible to determine the evolutionary mechanisms responsible for these differences, whether a consequence of genetic adaptation to fluctuating food supplies ("ecological risk aversion hypothesis") or phenotypic plasticity in response to the abundance of food ("energy balance hypothesis"). Our results do not seem consistent with the extrinsic mortality risks at each site, but current conditions for mountain gorillas are unlikely to match their evolutionary history. Not all traits fell along the expected fast-slow continuum, which illustrates that they can vary independently from each other ("modularity model"). Thus, the life history traits of each gorilla population may reflect a complex interplay of multiple ecological influences that are operating through both genetic adaptations and phenotypic plasticity.
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Affiliation(s)
- Martha M Robbins
- Department of Primate Behavior and Evolution, Max Planck Institute for Evolutionary Anthropology, Leipzig, Germany
| | - Moses Akantorana
- Department of Primate Behavior and Evolution, Max Planck Institute for Evolutionary Anthropology, Leipzig, Germany
| | | | - Thomas Breuer
- Mbeli Bai Study, Wildlife Conservation Society Congo Program, Brazzaville, Democratic Republic of the Congo
- World Wide Fund for Nature, Berlin, Germany
| | - Marie Manguette
- Mbeli Bai Study, Wildlife Conservation Society Congo Program, Brazzaville, Democratic Republic of the Congo
| | - Shannon McFarlin
- Department of Anthropology, Center for the Advanced Study of Human Paleobiology, The George Washington University, Washington, DC, USA
| | - Angela Meder
- Berggorilla Regenwald Direkthilfe, Hoevelhof, Germany
| | - Richard Parnell
- Mbeli Bai Study, Wildlife Conservation Society Congo Program, Brazzaville, Democratic Republic of the Congo
| | - Jack L Richardson
- Department of Anthropology, Center for the Advanced Study of Human Paleobiology, The George Washington University, Washington, DC, USA
| | - Claudia Stephan
- Mbeli Bai Study, Wildlife Conservation Society Congo Program, Brazzaville, Democratic Republic of the Congo
- Nouabalé-Ndoki Foundation, Brazzaville, Democratic Republic of the Congo
| | - Emma J Stokes
- Mbeli Bai Study, Wildlife Conservation Society Congo Program, Brazzaville, Democratic Republic of the Congo
| | - Tara S Stoinski
- Dian Fossey Gorilla Fund International, Atlanta, Georgia, USA
| | | | - Andrew M Robbins
- Department of Primate Behavior and Evolution, Max Planck Institute for Evolutionary Anthropology, Leipzig, Germany
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Robbins MM. Reflections on connections. Primates 2023; 64:191-197. [PMID: 36867278 PMCID: PMC9982802 DOI: 10.1007/s10329-023-01059-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2023] [Accepted: 02/18/2023] [Indexed: 03/04/2023]
Affiliation(s)
- Martha M Robbins
- Department of Primate Behavior and Evolution, Max Planck Institute for Evolutionary Anthropology, Leizpig, Germany.
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