Population dynamics of western gorillas at Mbeli Bai.

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 Nationa...

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Main Authors: Andrew M Robbins, Marie L Manguette, Thomas Breuer, Milou Groenenberg, Richard J Parnell, Claudia Stephan, Emma J Stokes, Martha M Robbins
Format: Article
Language:English
Published: Public Library of Science (PLoS) 2022-01-01
Series:PLoS ONE
Online Access:https://doi.org/10.1371/journal.pone.0275635
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author Andrew M Robbins
Marie L Manguette
Thomas Breuer
Milou Groenenberg
Richard J Parnell
Claudia Stephan
Emma J Stokes
Martha M Robbins
author_facet Andrew M Robbins
Marie L Manguette
Thomas Breuer
Milou Groenenberg
Richard J Parnell
Claudia Stephan
Emma J Stokes
Martha M Robbins
author_sort Andrew M Robbins
collection DOAJ
description 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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spelling doaj.art-23e3b40da44143cbb6ec49af80a60ab82022-12-31T05:32:27ZengPublic Library of Science (PLoS)PLoS ONE1932-62032022-01-011710e027563510.1371/journal.pone.0275635Population dynamics of western gorillas at Mbeli Bai.Andrew M RobbinsMarie L ManguetteThomas BreuerMilou GroenenbergRichard J ParnellClaudia StephanEmma J StokesMartha M RobbinsLong-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.https://doi.org/10.1371/journal.pone.0275635
spellingShingle Andrew M Robbins
Marie L Manguette
Thomas Breuer
Milou Groenenberg
Richard J Parnell
Claudia Stephan
Emma J Stokes
Martha M Robbins
Population dynamics of western gorillas at Mbeli Bai.
PLoS ONE
title Population dynamics of western gorillas at Mbeli Bai.
title_full Population dynamics of western gorillas at Mbeli Bai.
title_fullStr Population dynamics of western gorillas at Mbeli Bai.
title_full_unstemmed Population dynamics of western gorillas at Mbeli Bai.
title_short Population dynamics of western gorillas at Mbeli Bai.
title_sort population dynamics of western gorillas at mbeli bai
url https://doi.org/10.1371/journal.pone.0275635
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