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Cited by 338Wildlife Ecology and ConservationCensus and Population EstimationAnimal Ecology and Behavior Studies

Monitoring mammal populations with line transect techniques in African forests

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Plumptre, Andrew J.·2000·Journal of Applied Ecology
DOI 10.1046/j.1365-2664.2000.00499.x
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Abstract

Summary 1. Line transect survey techniques have been used to estimate population density for a variety of mammal species in tropical forests. In many cases indirect methods, surveying signs of animals such as counts of dung or nests, have been used because of the poor visibility in these forests. The estimates of the production and decomposition rates of these signs each have their associated errors; however, for the majority of published studies these errors have not been incorporated into the estimate of the standard errors or confidence limits of the density estimate. An equation is given showing how this should be done. 2. An equation is also given relating the resolution (R) of a density estimate to the coefficient of variation (CV) of the estimate. This shows that to detect a 10% change in a population the CV must be 3·6% (with a power of 50%) or 2·4% (with 80% power). Using this equation and data from studies in Africa, it is shown that differences of less than 10–30% change in the population are unlikely to be detected between two surveys where visual sightings of animals are made. When indirect methods of estimating the population are used, it is unlikely that less than a 30–50% change in the population could be detected. 3. Some studies have surveyed primate groups using estimates of an average group spread. Data from primate groups in Budongo Forest, Uganda, show that group spread is highly variable and varies at different times of day and between months. This survey technique is not recommended. 4. If line transects are used for monitoring populations, conversion factors should be minimized as each contributes to an increase in the CV and a reduction in the ability to detect small changes in population density. 5. Monitoring trends in abundance over several survey periods can improve the detection of change, although this is costly and requires several surveys before any conclusions can be reached. Re‐using transects in subsequent surveys can also reduce the variation around the estimate and will improve the resolution. Focusing survey efforts in areas of high density is an alternative strategy, but one that could lead to other errors as high‐density areas may be the safest and hence the last to show change. Using biased survey methods is also a promising technique that can increase the precision of surveys. It is concluded that a combination of different survey methods will ensure that changes in abundance are identified.

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  • Transect methods using spoor and droppings must deal with differences in skill levels of those conducting the survey, and decay and defecation rates, all of which contribute to inaccuracy and increased variance in abundance estimates.

    “Transect methods using spoor and droppings must deal with differences in skill levels of those conducting the survey, and decay and defecation rates, all of which contribute to inaccuracy and increased variance in abundance estimates (Plumptre, 2000).”

    From Field surveys for the Endangered pygmy hippopotamus <i>Choeropsis liberiensis</i> in Sapo National Park, Liberia (2011) · cites this paper as Plumptre, 2000

    The Defaecation rates section says errors in deposition and decay rates should be included in estimates from indirect counts; the Decay rates section says variation in decay rates reduces the resolution of dung and nest counts. These passages support the concern about inaccurate or imprecise abundance estimates, but the passages found do not address differences in surveyors’ skill levels or specifically discuss spoor. Page numbers are not available in our copy. (LLM, conf=0.84)

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3 of the 36 references couldn’t be matched to a known paper.

Research works printed but not linked: 9

  1. Dawson, S. (1990) A model to estimate density of Asian ele- phants (Elephus maximus) in forest habitats. MSc The- sis. Oxford University, Oxford, UK.
  2. Laake, J.L., Burnham, K.P. & Anderson, D.R. (1979) Users' Manual for Program TRANSECT. Utah State University Press, Logan, UT.
  3. Ruggiero, R.G. (1990) The ecology and conservation of the African elephant (Loxodonta african). PhD Thesis. University of Ann Arbor, Ann Arbor, MI.
  4. Staines, B.W. & Ratclie, P.R. (1987) Estimating the abun- dance of red deer (Cervus elaphus L.) and roe deer (Capreolus capreolus L.) and their current status in Great Britain. Symposium of the Zoological Society of London, 58, 131±152.
  5. Struhsaker, T.T. (1997) Ecology of an African Rain Forest. University Press of Florida, Gainesville, FL.
  6. White, L.J.T. (1992) Vegetation history and logging distur- bance: eects on rainforest mammals in the Lope Reserve, Gabon. PhD Thesis. University of Edinburgh, Edinburgh, UK.
  7. White, L.J.T. (1995) Factors aecting the duration of ele- phant dung piles in rain forest in the Lope Reserve, Gabon. African Journal of Ecology, 33, 142±150.
  8. Whitesides, G.H., Oates, J.F., Green, S.M. & Kluberdanz, R.P. (1988) Estimating primate densities from transects in a West African rainforest: a comparison of techni- ques. Journal of Animal Ecology, 57, 345±367.
  9. Wrogemann, D. (1992) Wild chimpanzees in Lope, Gabon: census method and habitat use. PhD Thesis. Bremen University, Bremen, Germany. Received 10 June 1998; revision received 28 December 1999

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Authors
Plumptre, A. J.
Affiliations
Wildlife Conservation Society (US)
Corresponding author
Plumptre, Andrew J.
ORCID
Plumptre, Andrew J.
Venue
Journal of Applied Ecology
Publisher
Wiley
Published
2000-04
Volume
37
Issue
2
Pages
356-368
ISSN
  • 0021-8901 (ISSN-L)
  • 1365-2664
DOI
10.1046/j.1365-2664.2000.00499.x
OpenAlex
W2006683025
Cited by
338
References
36
Citations by year
2026: 10 · 2025: 10 · 2024: 3 · 2023: 11 · 2022: 10 · 2021: 18 · 2020: 14 · 2019: 8 · 2018: 7 · 2017: 10 · 2016: 8 · 2015: 15 · 2014: 12 · 2013: 41 · 2012: 26
FWCI
7.29
Type
journal article
Language
en
Open access
Licence
onlinelibrary.wiley.com/termsAndConditions#vor (vor, 633 d)
Locations
Journal of Applied Ecology (publishedVersion)
Funders
  • Wildlife Conservation Society
  • Fauna and Flora International
  • University of Oxford
  • University of Bristol
Topics
  • Physical Sciences › Environmental Science › Ecology › Wildlife Ecology and Conservation
  • Physical Sciences › Mathematics › Statistics and Probability › Census and Population Estimation
  • Physical Sciences › Environmental Science › Ecology › Animal Ecology and Behavior Studies
Keywords
line transect survey, population monitoring, detection probability, coefficient of variation, dung counts, conversion factors, survey bias, Budongo Forest, African tropical forests

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