Estimating Forest Elephant Numbers with Dung Counts and a Geographic Information System

Barnes, R. F. W.; Beardsley, Karen; Michelmore, Frances; Barnes, Keith; Alers, M. P. T.; Blom, A.

doi:10.2307/3802142

Cited by 56 publications

(47 citation statements)

References 28 publications

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“…The impacts of humans on the density and distribution of elephants in Central Africa is well known (Barnes et al, 1997), and there is a similar relationship for other species (Noss 1995(Noss , 1998Lahm et al, 1998;Blom, 2001). The effect of human disturbance varies greatly, depending on its nature and intensity, and understanding this interaction is essential for managing protected areas (Prins & Reitsma, 1989;White, 1994;Fitzgibbon et al, 1995;Oates, 1996;Hall et al, 1998).…”

Section: Introductionmentioning

confidence: 88%

Factors influencing the distribution of large mammals within a protected central African forest

Blom

Zalinge

Heitkönig

et al. 2005

ORX

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This paper presents the analyses of data obtained from eight permanent 20 km transects to determine the relative effect of local human populations and ecological factors on the distribution of large mammals within the Dzanga sector of the Dzanga-Ndoki National Park and the adjacent area of the Dzanga-Sangha Dense Forest Special Reserve in south-west Central African Republic. Principal component analysis indicated that human activities significantly influence the distribution of large mammals, even within this protected area. Distance from the village and the main road as well as the distance from secondary roads appeared to have the greatest influence. Elephants in particular were significantly less common in areas related to human use. Our study showed that poachers use roads, both primary and secondary, to penetrate into the National Park. Thus increasing anti-poaching efforts along these roads could be an effective protection measure.

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Section: Introductionmentioning

confidence: 88%

Factors influencing the distribution of large mammals within a protected central African forest

Blom

Zalinge

Heitkönig

et al. 2005

ORX

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“…The objective of the study presented here was to determine the e¡ect of local human populations on the density and distribution of wildlife within such a protected area, the Dzanga sector of the Dzanga-Ndoki National Park and the adjacent area of the Dzanga-Sangha Dense Forest Special Reserve in south-western Central African Republic (Fig.1). Other studies have analysed species distributions by comparing regions with varying levels of human disturbance (Tutin & Fernandez, 1984;Prins & Reitsma, 1989;White, 1994;Fitzgibbon, Mogoka & Fanshawe, 1995;Oates, 1996;Hall et al, 1998;Remis, 2000), but few have actually tried to quantify the relationship in a more detailed manner (but see Barnes et al, 1997;Lahm et al, 1998 for notable exceptions). By looking at the in£uence of human activities on a range of di¡erent species, we hope to obtain a better understanding of human impact on the Dzanga-Sangha protected area complex.…”

Section: Introductionmentioning

confidence: 97%

Human impact on wildlife populations within a protected Central African forest

Blom

Heitkönig

Prins

et al. 2004

African Journal of Ecology

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This paper addresses the e¡ect of human activities on the density of large mammals in the Dzanga-Ndoki National Park and the adjacent Dzanga-Sangha Reserve in the Central African Republic.Between six and eight 20 km long permanent transects were walked on a monthly basis from January 1997 to August 1999 to assess large mammal populations as well as human intrusion. There were no obvious seasonal or monthly trends in elephant, gorilla or non-human primate densities.Overall, it appears that human activities negatively in£uence the distribution of most of the large forest animals in Dzanga-Sangha. Elephants in particular were signi¢cantly less common in areas used by humans, but also other species such as non-human primates showed lower densities closer to the main road and the town of Bayanga.This studycon¢rms the ¢ndings of previous studies that roads have a negative impact on wildlife populations.Results of this study stress the need for conservation of large uninterrupted forest blocks to maintain wildlife populations at normal levels. Simply creating roads, even within a protected Central African forest, is likely to have negative impacts on wildlife populations.

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“…Dung has long been an effective means to survey elusive forest species, including small animals, macropods, ungulates, and forest elephants (Barnes 2000;Barnes et al 1997;Fuller 1991;Merz 1986;Nchanji and Plumptre 2001;Neff 1968;Plumptre and Harris 1995;Tchamba 1992;Walsh and White 1999). Gorilla dung piles are more numerous and decay faster than nests, which is more in keeping with the steady-state assumption on which researchers have based most gorilla densities (McClanahan 1986;Kuehl et al 2007).…”

Section: Introductionmentioning

confidence: 62%

“…In any case, the effects of rainfall on dung production rates imply that assuming a constant defecation rate (Barnes 2001;Barnes et al 1997;Fuller 1991;Merz 1986;Neff 1968;Plumptre and Harris 1995;Tchamba 1992) produces biased density estimates. For example, we used transect surveys at Bai Hokou to estimate a wet season gorilla dung density of 32/km 2 (Todd, unpub.…”

Section: Seasonal Variationmentioning

confidence: 99%

Using Dung to Estimate Gorilla Density: Modeling Dung Production Rate

et al. 2008

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There is an urgent need for information on western gorilla population sizes and distribution to improve present and plan future conservation actions. Researchers traditionally have estimated gorilla densities on the basis of nest counts despite demonstrated variation in nest production and decay rates. The variation may lead to large biases in estimates of gorilla abundance. We investigated the use of an alternate index of gorilla abundance, via defecation data collected from habituated gorillas at Bai Hokou, Central African Republic. Our sample of 274/370 defecation events/dung piles produced a production rate of ca. 5 dung piles/d: comparable to previous estimates based on much smaller sample sizes. Heuristic models that failed to account for imperfect dung pile detection produced a lower defecation rate estimate than that of a maximum likelihood model that explicitly modeled detection probability. Generalized linear modeling (GLM) showed that dung pile production rate was strongly linked to rainfall, suggesting that failure to correct for seasonal variation in dung pile production rates could lead to substantial biases in gorilla abundance estimates. In our study, failing to distinguish between the number of defecation events and the number of dung piles produced would lead to a ca. 31% overestimate of true gorilla numbers. The use of dung as an index of gorilla abundance shows potential, but more fieldwork and modeling on seasonal variation in dung production rates is required.

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Estimating Forest Elephant Numbers with Dung Counts and a Geographic Information System

Cited by 56 publications

References 28 publications

Factors influencing the distribution of large mammals within a protected central African forest

Factors influencing the distribution of large mammals within a protected central African forest

Human impact on wildlife populations within a protected Central African forest

Using Dung to Estimate Gorilla Density: Modeling Dung Production Rate

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