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Gautam H, Vidya TNC. Do food distribution and competitor density affect agonistic behaviour within and between clans in a high fission-fusion species? ROYAL SOCIETY OPEN SCIENCE 2023; 10:230990. [PMID: 38077213 PMCID: PMC10698478 DOI: 10.1098/rsos.230990] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 07/11/2023] [Accepted: 11/13/2023] [Indexed: 01/11/2024]
Abstract
According to the ecological model of female social relationships (EMFSR), within-group competition and between-group competition in female-bonded species are shaped by food distribution. Strong between-group contests are expected over large, monopolizable resources and high population density, but not when low-quality food is distributed across large, undefended home ranges. Within-group contests are expected to be more frequent with increasing heterogeneity among feeding sites and with group size. We tested these predictions in female Asian elephants, which show traits associated with infrequent contests-graminivory, high fission-fusion and overlapping home ranges. We examined how food distribution and competitor density affected agonistic interactions within and between female elephant clans (social groupings) in the Kabini grassland, southern India. We found stronger between-clan contest in the grassland than that known from neighbouring forests, and more frequent agonism between females between clans than within clans. Such strong between-clan contest was attributable to the grassland being a food-rich habitat patch, thus supporting the EMFSR. Within-clan agonism was also frequent, but did not increase with food heterogeneity, contradicting the EMFSR. Contrary to recent claims, increasing within-clan agonism with group size suggested ecological constraints on large groups despite high fission-fusion. High population density may explain such frequent contests despite graminivory and fission-fusion.
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Affiliation(s)
- Hansraj Gautam
- Evolutionary and Organismal Biology Unit, Jawaharlal Nehru Centre for Advanced Scientific Research (JNCASR), Bengaluru, India
| | - T. N. C. Vidya
- Evolutionary and Organismal Biology Unit, Jawaharlal Nehru Centre for Advanced Scientific Research (JNCASR), Bengaluru, India
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2
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Williams L, Shultz S, Jensen K. The primate workplace: Cooperative decision-making in human and non-human primates. Front Ecol Evol 2022. [DOI: 10.3389/fevo.2022.887187] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
The success of group foraging in primates is not only determined by ecological and social factors. It is also influenced by cognition. Group foraging success is constrained, for instance, by the challenges of coordination, synchrony and decision-making, and it is enhanced by the ability to share, learn from others and coordinate actions. However, what we currently know about the cognition of individuals in groups comes primarily from experiments on dyads, and what we know of the effect of ecological factors on group dynamics comes from larger wild groups. Our current knowledge of primate group behaviour is thus incomplete. In this review, we identify a gap in our knowledge of primate group dynamics between the dyadic studies on primate cooperation and the large group observational studies of behavioural ecology. We highlight the potential for controlled experimental studies on coordination and cooperation in primate groups. Currently, these exist primarily as studies of dyads, and these do not go far enough in testing limits of group-level behaviours. Controlled studies on primate groups beyond the dyad would be highly informative regarding the bounds of non-human primate collaboration. We look to the literature on how humans behave in groups, specifically from organisational psychology, draw parallels between human and non-human group dynamics and highlight approaches that could be applied across disciplines. Organisational psychology is explicitly concerned with the interactions between individuals in a group and the emergent properties at the group-level of these decisions. We propose that some of the major shortfalls in our understanding of primate social cognition and group dynamics can be filled by using approaches developed by organisational psychologists, particularly regarding the effects of group size and composition on group-level cooperation. To illustrate the potential applications, we provide a list of research questions drawn from organisational psychology that could be applied to non-human primates.
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3
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Robbins AM, Manguette ML, Breuer T, Groenenberg M, Parnell RJ, Stephan C, Stokes EJ, Robbins MM. Population dynamics of western gorillas at Mbeli Bai. PLoS One 2022; 17:e0275635. [PMID: 36260834 PMCID: PMC9581538 DOI: 10.1371/journal.pone.0275635] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2022] [Accepted: 09/20/2022] [Indexed: 11/19/2022] Open
Abstract
Long-term studies of population dynamics can provide insights into life history theory, population ecology, socioecology, conservation biology and wildlife management. Here we examine 25 years of population dynamics of western gorillas at Mbeli Bai, a swampy forest clearing in Nouabalé-Ndoki National Park, the Republic of Congo. The Mbeli population more than doubled from 101 to 226 gorillas during the study. After adjusting for a net influx of gorillas into the study population, the increase represents an inherent growth rate of 0.7% per year, with 95% confidence limits between -0.7% and 2.6%. The influx of gorillas mainly involved immigration of individuals into existing study groups (social dispersal), but it also included the appearance of a few previously unknown groups (locational dispersal). The average group size did not change significantly during the study, which is consistent with the possibility that western gorillas face socioecological constraints on group size, even when the population is increasing. We found no significant evidence of density dependence on female reproductive success or male mating competition. The distribution of gorillas among age/sex categories also did not change significantly, which suggests that the population had a stable age structure. Our results provide evidence of population stability or growth for some western gorillas (albeit within a small area). The results highlight the value of law enforcement, long-term monitoring, and protected areas; but they do not diminish the importance of improving conservation for this critically endangered species.
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Affiliation(s)
- Andrew M. Robbins
- Wildlife Conservation Society–Congo Program, Brazzaville, Republic of Congo
- * E-mail:
| | - Marie L. Manguette
- Wildlife Conservation Society–Congo Program, Brazzaville, Republic of Congo
- Nouabalé-Ndoki Foundation, Brazzaville, Republic of Congo
| | - Thomas Breuer
- Nouabalé-Ndoki Foundation, Brazzaville, Republic of Congo
- Division of Developmental Biology, Friedrich-Alexander University Erlangen, Erlangen, Germany
| | | | - Richard J. Parnell
- Wildlife Conservation Society, Global Conservation Program, Bronx, NY, United States of America
| | - Claudia Stephan
- Wildlife Conservation Society–Congo Program, Brazzaville, Republic of Congo
- Nouabalé-Ndoki Foundation, Brazzaville, Republic of Congo
- Division of Developmental Biology, Friedrich-Alexander University Erlangen, Erlangen, Germany
| | - Emma J. Stokes
- Wildlife Conservation Society, Global Conservation Program, Bronx, NY, United States of America
| | - Martha M. Robbins
- Wildlife Conservation Society–Congo Program, Brazzaville, Republic of Congo
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4
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Teichroeb JA, Adams FV, Khwaja A, Stapelfeldt K, Stead SM. Tight quarters: ranging and feeding competition in a Colobus angolensis ruwenzorii multilevel society occupying a fragmented habitat. Behav Ecol Sociobiol 2022. [DOI: 10.1007/s00265-022-03166-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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5
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Petrželková K, Samaš P, Romportl D, Uwamahoro C, Červená B, Pafčo B, Prokopová T, Cameira R, Granjon A, Shapiro A, Bahizi M, Nziza J, Noheri J, Syaluha E, Eckardt W, Ndagijimana F, Šlapeta J, Modrý D, Gilardi K, Muvunyi R, Uwingeli P, Mudakikwa A, Mapilanga J, Kalonji A, Hickey J, Cranfield M. Ecological drivers of helminth infection patterns in the Virunga Massif mountain gorilla population. Int J Parasitol Parasites Wildl 2022; 17:174-184. [PMID: 35145846 PMCID: PMC8802862 DOI: 10.1016/j.ijppaw.2022.01.007] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2021] [Revised: 01/07/2022] [Accepted: 01/17/2022] [Indexed: 01/16/2023]
Abstract
The Virunga Massif mountain gorilla population has been periodically monitored since the early 1970s, with gradually increasing effort. The population declined drastically in the 1970s, but the numbers stabilized in the 1980s. Since then, the population has been steadily increasing within their limited habitat fragment that is surrounded by a dense human population. We examined fecal samples collected during the Virunga 2015-2016 surveys in monitored and unmonitored gorilla groups and quantified strongylid and tapeworm infections using egg counts per gram to determine environmental and host factors that shape these helminth infections. We showed that higher strongylid infections were present in gorilla groups with smaller size of the 500-m buffered minimum-convex polygon (MCP) of detected nest sites per gorilla group, but in higher gorilla densities and inhabiting vegetation types occurring at higher elevations with higher precipitation and lower temperatures. On the contrary, the impact of monitoring (habituation) was minor, detected in tapeworms and only when in the interaction with environmental variables and MCP area. Our results suggest that the Virunga mountain gorilla population may be partially regulated by strongylid nematodes at higher gorilla densities. New health challenges are probably emerging among mountain gorillas because of the success of conservation efforts, as manifested by significant increases in gorilla numbers in recent decades, but few possibilities for the population expansion due to limited amounts of habitat.
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Affiliation(s)
- K.J. Petrželková
- Institute of Vertebrate Biology, Czech Academy of Sciences, Brno, Czech Republic
- Biology Centre, Institute of Parasitology, Czech Academy of Sciences, České Budějovice, Czech Republic
- Liberec Zoo, Liberec, Czech Republic
| | - P. Samaš
- Institute of Vertebrate Biology, Czech Academy of Sciences, Brno, Czech Republic
| | - D. Romportl
- Department of Physical Geography and Geoecology, Faculty of Science, Charles University, Prague, Czech Republic
| | | | - B. Červená
- Institute of Vertebrate Biology, Czech Academy of Sciences, Brno, Czech Republic
- Department of Pathology and Parasitology, Faculty of Veterinary Medicine, University of Veterinary Sciences, Brno, Czech Republic
| | - B. Pafčo
- Institute of Vertebrate Biology, Czech Academy of Sciences, Brno, Czech Republic
| | - T. Prokopová
- Institute of Vertebrate Biology, Czech Academy of Sciences, Brno, Czech Republic
- Department of Pathology and Parasitology, Faculty of Veterinary Medicine, University of Veterinary Sciences, Brno, Czech Republic
| | - R. Cameira
- Institute of Vertebrate Biology, Czech Academy of Sciences, Brno, Czech Republic
- Department of Pathology and Parasitology, Faculty of Veterinary Medicine, University of Veterinary Sciences, Brno, Czech Republic
| | - A.C. Granjon
- Department of Primatology, Max Planck Institute for Evolutionary Anthropology, Leipzig, Germany
| | - A. Shapiro
- Here + There Mapping Solutions, Berlin, Germany
| | - M. Bahizi
- Gorilla Doctors (MGVP, Inc.), Davis, CA, USA
| | - J. Nziza
- Gorilla Doctors (MGVP, Inc.), Davis, CA, USA
| | - J.B. Noheri
- Gorilla Doctors (MGVP, Inc.), Davis, CA, USA
| | | | - W. Eckardt
- Dian Fossey Gorilla Fund, Musanze, Rwanda
| | | | - J. Šlapeta
- Sydney School of Veterinary Science, Faculty of Science, The University of Sydney, New South Wales 2006, Australia
| | - D. Modrý
- Biology Centre, Institute of Parasitology, Czech Academy of Sciences, České Budějovice, Czech Republic
- Department of Pathology and Parasitology, Faculty of Veterinary Medicine, University of Veterinary Sciences, Brno, Czech Republic
- Department of Botany and Zoology, Faculty of Science, Masaryk University, Brno, Czech Republic
- Department of Veterinary Sciences/CINeZ, Faculty of Agrobiology, Food and Natural Resources, Czech University of Life Sciences Prague, Prague, Czech Republic
| | - K. Gilardi
- Gorilla Doctors (MGVP, Inc.), Davis, CA, USA
- School of Veterinary Medicine, University of California, Davis, CA, USA
| | - R. Muvunyi
- Rwanda Development Board, Kigali, Rwanda
| | | | | | - J. Mapilanga
- Institut Congolais pour la Conservation de la Nature, Kinshasa, Congo
| | - A. Kalonji
- Institut Congolais pour la Conservation de la Nature, Parc National de Kahuzi Biega, Bukavu, Congo
| | - J.R. Hickey
- International Gorilla Conservation Programme, Kigali, Rwanda
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6
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Wikberg EC, Gonzalez S, Rodriguez C, Sicotte P. Joint intergroup aggression in female colobus monkeys (Colobus vellerosus) is associated with grooming bonds, male participation, and group size. Am J Primatol 2021; 84:e23355. [PMID: 34927751 DOI: 10.1002/ajp.23355] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2021] [Revised: 12/10/2021] [Accepted: 12/12/2021] [Indexed: 11/06/2022]
Abstract
Cooperative home range defense is common in primates, despite a collective action problem that arises when group members benefit from winning the intergroup encounter regardless of whether they participate. The costs associated with this collective action problem may be mitigated by residing in small groups, residing with kin, or by forming strong bonds with group members. The potential to decouple the effects of these variables provided an opportunity to investigate which of these three variables best explains coparticipation in intergroup encounters among adult and subadult female colobus at Boabeng-Fiema, Ghana. Because males are often the main participants, we also investigated the relationship between female-female coparticipation and adult and subadult male participation. We collected intergroup behaviors from 94 adult and subadult individuals in eight groups during 1 year. We quantified female grooming bond strength and approach rates using focal samples. We classified female dyads as close kin (i.e., halfsiblings or more closely related) or nonkin based on partial pedigrees and genotypes generated from 17 STR loci. Female-female coparticipation was higher in dyads with stronger grooming bonds but was not associated with dyadic kinship, approach rate, or age class. Female coparticipation decreased with increasing female group size as expected if there is a collective action problem. Females coparticipated less in groups with more males and male intergroup aggression, possibly because there is less need for female-female cooperation if males are participating in the intergroup encounter. Females in smaller groups may not only benefit from increased female-female cooperation during intergroup encounters, they are also likely to reside with a higher-quality alpha male, both of which may increase the likelihood of winning intergroup encounters. There may be strong selection for facultative female dispersal in populations like the Boabeng-Fiema colobus in which small groups are associated with multiple benefits and cooperation is not affected by kinship.
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Affiliation(s)
- Eva C Wikberg
- Department of Anthropology, University of Texas at San Antonio, Texas, USA
| | - Sofia Gonzalez
- Department of Anthropology, University of Texas at San Antonio, Texas, USA
| | - Cynthia Rodriguez
- Department of Anthropology, University of Texas at San Antonio, Texas, USA
| | - Pascale Sicotte
- Department of Anthropology and Archaeology, University of Calgary, Calgary, Alberta, Canada.,Department of Biology, Concordia University, Montréal, Quebec, Canada
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7
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Dissecting the two mechanisms of scramble competition among the Virunga mountain gorillas. Behav Ecol Sociobiol 2021; 75:82. [PMID: 34776593 PMCID: PMC8550613 DOI: 10.1007/s00265-021-03016-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2020] [Revised: 03/24/2021] [Accepted: 03/30/2021] [Indexed: 11/30/2022]
Abstract
Abstract Two mechanisms have been proposed to explain why scramble competition can increase the travel requirements of individuals within larger groups. Firstly, individuals in larger groups may be more likely to encounter food sites where other group members have already eaten, leading to greater asynchronous “individual” travel to find fresh sites. Secondly, when food sites are aggregated into patches, larger groups may need to visit more patches to obtain the same amount of food per capita, leading to greater synchronous “group” travel between patches. If the first mechanism can be mitigated by increasing group spread, then we expect the second mechanism to be more sensitive to group size. Here, we examine the individual travel and group travel of the Virunga mountain gorillas, along with potential implications for the two mechanisms of scramble competition. Asynchronous individual travel accounted for 67% of the total travel time, and the remainder arose from group travel. Group spread increased significantly for larger groups, but not enough to prevent an increase in individual travel. Contrary to expectations, group travel decreased with size among most groups, and we found only limited evidence of patch depletion that would cause the second mechanism of scramble competition. Collectively, our results illustrate how the influence of group size can differ for individual travel versus group travel, just as it differs among species for overall travel. Studies that distinguish between the two mechanisms of scramble competition may enhance our understanding of ecological constraints upon group size, including potential differences between frugivores and folivores. Significance statement Feeding competition provides insight into how group size can influence the foraging patterns of social animals, but two key mechanisms are not typically compared. Firstly, larger groups may visit more patches to access the same amount of food per capita (group travel). Secondly, their individuals may also need to move past more spots where another member has already eaten (individual travel). Contrary to expectations, we found that group travel decreased with size for most groups of mountain gorillas, which may reflect extra travel by smaller groups to avoid larger groups. Individual travel increased with size in most groups, even though gorillas in larger groups compensated by spreading out over a broader area. The two mechanisms revealed patterns that were not apparent in our previous study of overall travel. Our approach may help to explain potential differences between folivores and frugivores.
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8
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Petrželková KJ, Uwamahoro C, Pafčo B, Červená B, Samaš P, Mudakikwa A, Muvunyi R, Uwingeli P, Gilardi K, Nziza J, Noheri JB, Eckardt W, Ndagijimana F, Ssebide B, Okwirokello R, Nizeyimana F, Syaluha EK, Nzayisenga G, Flores Girón L, Bahizi M, Ntwari AE, Lukusa JP, Tumushime JC, Mangura D, Mapilanga J, Kalonji A, Aruho R, Stryková A, Tehlarová Z, Cameira R, Lowenstine L, Šlapeta J, Romportl D, Ferrari N, Cranfield M, Modrý D. Heterogeneity in patterns of helminth infections across populations of mountain gorillas (Gorilla beringei beringei). Sci Rep 2021; 11:10869. [PMID: 34035316 PMCID: PMC8149636 DOI: 10.1038/s41598-021-89283-4] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2020] [Accepted: 04/20/2021] [Indexed: 02/04/2023] Open
Abstract
Conservation efforts have led to the recovery of the endangered mountain gorilla populations. Due to their limited potential for spatial expansion, population densities increased, which may alter the epidemiology of infectious diseases. Recently, clinical gastrointestinal illnesses linked to helminth infections have been recorded in both gorilla populations. To understand drivers and patterns of helminth infections we quantified strongylid and tapeworm infections across both Virunga Massif and Bwindi populations using fecal egg counts. We assessed the impact of age, sex, group size, season and spatial differences used as a proxy, which reflects observed variation in the occurrence of gastrointestinal problems, vegetation types, gorilla subpopulation growth and associated social structure on helminth infections. We revealed striking geographic differences in strongylid infections with higher egg counts mostly in areas with high occurrences of gastrointestinal disease. Increased helminth egg counts were also associated with decreasing group size in some areas. Observed spatial differences may reflect mutual effects of variations in subpopulation growth rates, gorilla social structure, and vegetation associated with altitude across mountain gorilla habitat. Helminth infection intensities in Virunga gorillas were lowest in the youngest and the oldest animals. Elucidating parasite infection patterns of endangered species with low genetic diversity is crucial for their conservation management.
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Affiliation(s)
- Klara J. Petrželková
- grid.418095.10000 0001 1015 3316Institute of Vertebrate Biology, The Czech Academy of Sciences, Brno, Czech Republic ,grid.418338.50000 0001 2255 8513Institute of Parasitology, Biology Centre, The Czech Academy of Sciences, Ceske Budejovice, Czech Republic ,Liberec Zoo, Liberec, Czech Republic
| | | | - Barbora Pafčo
- grid.418095.10000 0001 1015 3316Institute of Vertebrate Biology, The Czech Academy of Sciences, Brno, Czech Republic
| | - Barbora Červená
- grid.418095.10000 0001 1015 3316Institute of Vertebrate Biology, The Czech Academy of Sciences, Brno, Czech Republic ,Department of Pathology and Parasitology, Faculty of Veterinary Medicine, University of Veterinary Sciences Brno, Brno, Czech Republic
| | - Peter Samaš
- grid.418095.10000 0001 1015 3316Institute of Vertebrate Biology, The Czech Academy of Sciences, Brno, Czech Republic
| | - Antoine Mudakikwa
- grid.508147.f0000 0000 9490 3868Rwanda Development Board, Kigali, Rwanda
| | - Richard Muvunyi
- grid.508147.f0000 0000 9490 3868Rwanda Development Board, Kigali, Rwanda
| | - Prosper Uwingeli
- grid.508147.f0000 0000 9490 3868Rwanda Development Board, Kigali, Rwanda
| | | | - Julius Nziza
- grid.508041.8Gorilla Doctors (MGVP, Inc.), Davis, CA USA
| | | | | | | | - Benard Ssebide
- grid.508041.8Gorilla Doctors (MGVP, Inc.), Davis, CA USA
| | | | | | | | | | - Luis Flores Girón
- Centre de Recherche en Sciences Naturelles de Lwiro, Lwiro, Democratic Republic of Congo ,Lwiro Primate Rehabilitation Center, Democratic Republic of Congo and Ivan Carter Wildlife Conservation Alliance, Orlando, FL USA
| | - Méthode Bahizi
- grid.508041.8Gorilla Doctors (MGVP, Inc.), Davis, CA USA
| | | | | | | | - Damien Mangura
- grid.508041.8Gorilla Doctors (MGVP, Inc.), Davis, CA USA
| | - Jeff Mapilanga
- Institut Congolais pour la Conservation de la Nature, Kinshasa, Democratic Republic of Congo
| | - Arthur Kalonji
- Institut Congolais pour la Conservation de la Nature, Parc National de Kahuzi Biega, Bukavu, Democratic Republic of Congo
| | - Robert Aruho
- grid.463699.7Uganda Wildlife Authority, Kampala, Uganda
| | - Anna Stryková
- Department of Pathology and Parasitology, Faculty of Veterinary Medicine, University of Veterinary Sciences Brno, Brno, Czech Republic
| | - Zuzana Tehlarová
- grid.418095.10000 0001 1015 3316Institute of Vertebrate Biology, The Czech Academy of Sciences, Brno, Czech Republic
| | - Rita Cameira
- grid.418095.10000 0001 1015 3316Institute of Vertebrate Biology, The Czech Academy of Sciences, Brno, Czech Republic ,Department of Pathology and Parasitology, Faculty of Veterinary Medicine, University of Veterinary Sciences Brno, Brno, Czech Republic
| | - Linda Lowenstine
- grid.27860.3b0000 0004 1936 9684School of Veterinary Medicine, University of California Davis, Davis, CA USA
| | - Jan Šlapeta
- grid.1013.30000 0004 1936 834XSydney School of Veterinary Science, Faculty of Science, University of Sydney, Sydney, Australia
| | - Dušan Romportl
- grid.4491.80000 0004 1937 116XDepartment of Physical Geography and Geoecology, Faculty of Science, Charles University, Prague, Czech Republic
| | - Nicola Ferrari
- grid.4708.b0000 0004 1757 2822Department of Veterinary Medicine, Università degli Studi di Milano, Milan, Italy ,grid.4708.b0000 0004 1757 2822Research Center Epidemiology and Molecular Surveillance of Infections ‘‘EpiSoMI’’, Università degli Studi di Milano, Milan, Italy
| | | | - David Modrý
- grid.418338.50000 0001 2255 8513Institute of Parasitology, Biology Centre, The Czech Academy of Sciences, Ceske Budejovice, Czech Republic ,Department of Pathology and Parasitology, Faculty of Veterinary Medicine, University of Veterinary Sciences Brno, Brno, Czech Republic ,grid.10267.320000 0001 2194 0956Department of Botany and Zoology, Faculty of Science, Masaryk University, Brno, Czech Republic
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van der Hoek Y, Binyinyi E, Ngobobo U, Stoinski TS, Caillaud D. Daily Travel Distances of Unhabituated Grauer's Gorillas (Gorilla beringei graueri) in a Low Elevation Forest. Folia Primatol (Basel) 2021; 92:112-125. [PMID: 33756464 DOI: 10.1159/000514626] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2020] [Accepted: 01/20/2021] [Indexed: 01/05/2023]
Abstract
To accurately determine the space use of animals, we need to follow animal movements over prolonged periods, which is especially challenging for the critically endangered Grauer's gorillas (Gorilla beringei graueri) in eastern Democratic Republic of the Congo (DRC). As a consequence, we know little about Grauer's gorillas, particularly from the lower elevational parts of their range. Between 2016 and 2018, we tracked unhabituated Grauer's gorillas in lowland forests (500-1,000 m a.s.l.), at the community-managed Nkuba Conservation Area in Nord Kivu (DRC) to provide estimates of daily travel distances (DTD), daily displacement distances (DDD), and the linearity of recorded paths expressed as the Linearity Index (LI): DDD/DTD. We found an average DTD of ∼1.3 km (range 0.05-5.0 km), with temporal variation among monthly averages; specifically, an increase in travel distance over the June-August dry season resulting in peak travel distances at the beginning of the September-December wet season. Daily displacements showed similar temporal variation, which resulted in a lack of obvious temporal patterns in LI. We conclude that the movement patterns of Grauer's gorillas in lowland forests, which are characterized by larger DTD than those of Grauer's gorillas that inhabit highland habitats, show similarity to travel distances of other predominantly frugivorous gorillas. Moreover, the observed temporal patterns in space use may be tentatively linked to temporal changes in fruit availability or consumption. These observations have consequences for our understanding of the ecological role that Grauer's gorillas play and provide baseline data to estimate current and future distributions, abundances, and carrying capacities of this highly threatened animal.
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Affiliation(s)
| | | | - Urbain Ngobobo
- The Dian Fossey Gorilla Fund International, Musanze, Rwanda
| | | | - Damien Caillaud
- Department of Anthropology, University of California, Davis, California, USA
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Morrison RE, Hirwa JP, Mucyo JPS, Stoinski TS, Vecellio V, Eckardt W. Inter‐group relationships influence territorial defence in mountain gorillas. J Anim Ecol 2020; 89:2852-2862. [DOI: 10.1111/1365-2656.13355] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2020] [Accepted: 08/06/2020] [Indexed: 11/27/2022]
Affiliation(s)
- Robin E. Morrison
- The Dian Fossey Gorilla Fund Musanze Rwanda
- Centre for Research in Animal Behaviour University of Exeter Exeter UK
| | | | | | - Tara S. Stoinski
- The Dian Fossey Gorilla Fund Musanze Rwanda
- The Dian Fossey Gorilla Fund Atlanta GA USA
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11
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Seiler N, Robbins MM. Using long-term ranging patterns to assess within-group and between-group competition in wild mountain gorillas. BMC Ecol 2020; 20:40. [PMID: 32677937 PMCID: PMC7367404 DOI: 10.1186/s12898-020-00306-6] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2018] [Accepted: 06/30/2020] [Indexed: 11/28/2022] Open
Abstract
Background Competition within and between social groups determines access to resources and can be inferred from space use parameters that reflect depletion of food resources and competitive abilities of groups. Using location data from 1998 to 2017, we investigated within- and between-group competition in 12 groups of wild mountain gorillas (Gorilla beringei beringei). As within-group feeding competition is expected to increase with group size, an increase in group size is predicted to lead to an increase in the size of annual home ranges and core areas, but to a decrease in fidelity (reuse of an area). Due to asymmetries in competitive abilities, larger groups are expected to have higher exclusivity (degree of non-shared space) of annual home ranges and core areas than smaller groups. Results We found evidence of within-group feeding competition based on a positive relationship between group size and both annual home range and core area size as well as a negative relationship between group size and core area fidelity. Additionally, fidelity of core areas was lower than of home ranges. Between-group competition was inferred from a trend for groups with more members and more males to have more exclusive home ranges and core areas. Lastly, annual core areas were largely mutually exclusive. Conclusions Our study suggests that non-territorial, group-living animals can have highly dynamic, long-term avoidance-based spacing patterns, both temporally and spatially, to maintain annual core area exclusivity among groups while concurrently shifting these areas annually within overlapping home ranges to avoid resource depletion. Despite ranging in larger home ranges and core areas, larger groups were able to maintain more exclusive ranges than smaller groups, suggesting a competitive advantage for larger groups in between-group competition in a non-territorial species. Together, these findings contribute to understanding how social animals make behavioral adjustments to mitigate the effects of intraspecific competition.
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Affiliation(s)
- Nicole Seiler
- Department of Primatology, Max Planck Institute for Evolutionary Anthropology, Deutscher Platz 6, 04103, Leipzig, Germany.
| | - Martha M Robbins
- Department of Primatology, Max Planck Institute for Evolutionary Anthropology, Deutscher Platz 6, 04103, Leipzig, Germany
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Female dispersal patterns influenced by male tenure duration and group size in western lowland gorillas. Behav Ecol Sociobiol 2020. [DOI: 10.1007/s00265-020-02863-8] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
Abstract
Abstract
Evaluating the factors influencing the patterns of female dispersal in mammals is critical to understanding its importance for male and female reproductive strategies and the evolution of social systems. In western lowland gorillas, females emigrate from their natal group (natal dispersal) but also disperse between groups multiple times in their life (secondary dispersal). This strategy is uncommon in primates and may reflect females seeking to reduce feeding competition or female choice for males that can provide protection against infanticide. In this study, we test how inbreeding avoidance, group size, and male competitive ability could influence female dispersal in western gorillas, using 25 natal and 285 secondary dispersal events collected over 20 years at Mbeli Bai. We found that while all females dispersed out of their natal group, presumably to avoid inbreeding, females also left their group before having their first offspring when the dominant male was not their father, pointing towards unconditional dispersal by nulliparous females. Regarding secondary dispersal, we found that females were more likely to stay with males that were at the beginning of their tenure than transfer and more likely to disperse away from (presumably old) males that were near the end of their tenure or closer to their death. Females were also more likely to leave larger groups for smaller ones suggesting a potential effect of within-group feeding competition or avoidance of outsider males or predators. This study highlights the intersexual conflict found in gorillas: while female choice for high-quality males may influence the formation of their relatively rare social system, smaller group size may be more important for females than previously thought, which runs counter to the males’ interest of having a high number of females.
Significance
Dispersal is a very important life strategy for most group-living mammals. Secondary dispersal by females is a rare behavior but is believed to be a counterstrategy against sexual coercion by males, reduces feeding competition, assists in predator avoidance, and facilitates mate choice. We studied the factors influencing secondary dispersal in western lowland gorillas. We found that the duration of male tenure and the size of the group influences female transfer decisions. This study shows that female reproductive strategies such as secondary dispersal may be very powerful to counter the risk of infanticide through female choice for better protector males but also to reduce the impact of feeding competition or to avoid predators or outsider males.
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Lewis RJ, Sandel AA, Hilty S, Barnett SE. The Collective Action Problem but Not Numerical Superiority Explains Success in Intergroup Encounters in Verreaux’s Sifaka (Propithecus verreauxi): Implications for Individual Participation and Free-Riding. INT J PRIMATOL 2020. [DOI: 10.1007/s10764-020-00155-6] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
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14
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Green SJ, Boruff BJ, Niyigaba P, Ndikubwimana I, Grueter CC. Chimpanzee ranging responses to fruit availability in a high-elevation environment. Am J Primatol 2020; 82:e23119. [PMID: 32187721 DOI: 10.1002/ajp.23119] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2019] [Revised: 02/06/2020] [Accepted: 02/15/2020] [Indexed: 11/07/2022]
Abstract
Most primates experience seasonal fluctuations in the availability of food resources and face the challenge of balancing energy expenditure with energy gain during periods of resource scarcity. This is likely to be particularly challenging in rugged, montane environments, where available energy is relatively low and travel costs are high. Chimpanzees (Pan troglodytes) show extensive behavioral diversity across study sites. Yet, as most research has focused on low- and mid-elevation sites, little is known on how chimpanzees respond to periods of low fruit availability in harsh montane environments. We use focal follow and phenology data to investigate how fruit availability influences daily path length and monthly home range in chimpanzees living in Nyungwe National Park, a montane forest in Rwanda. Nyungwe chimpanzees decreased their daily travel distances during periods of fruit scarcity. However, this decrease in travel effort did not correspond with a decrease in foraging area. Instead, monthly homes ranges shifted location across the study period. Nyungwe chimpanzees occupy a relatively wide altitudinal range and the shifts in monthly home range location may reflect differences in the altitudinal distribution of food resources. Chimpanzee monthly diet was often dominated by one or two species and each of these species were confined to different elevation zones. One important species, Podocarpus latifolius, grew only at high elevations (2,600-2,950 m) and chimpanzees ranged at the altitudinal peak of their range for 2 consecutive months while feeding on this species. Thus, while high elevations are often thought to be harsh environments for primates, they can be an important part of a species' home range when they provide a refugium for densely distributed, important food species.
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Affiliation(s)
- Samantha J Green
- School of Human Sciences, The University of Western Australia, Perth, Australia.,UWA Africa Research & Engagement Centre, The University of Western Australia, Perth, Australia
| | - Bryan J Boruff
- School of Agriculture and Environment, The University of Western Australia, Perth, Australia
| | | | | | - Cyril C Grueter
- School of Human Sciences, The University of Western Australia, Perth, Australia.,UWA Africa Research & Engagement Centre, The University of Western Australia, Perth, Australia.,Centre for Evolutionary Biology, School of Biological Sciences, The University of Western Australia, Perth, Australia
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