Assessment of in situ nest decay rate for chimpanzees (Pan troglodytes ellioti Matschie, 1914) in Mbam-Djerem National Park, Cameroon: implications for long-term monitoring

Accurate assessment of great ape populations is a prerequisite for conservation planning. Indirect survey methods using nest and dung, and a set of conversion parameters related to nest decay rates, are increasingly used. Most surveys use the standing crop nest count (SCNC) method, whereby nests are...

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Bibliographic Details
Published in:Primates 2020-03, Vol.61 (2), p.189-200
Main Authors: Kamgang, Serge Alexis, Carme, Tuneu Corral, Bobo, Kadiri Serge, Abwe, Ekwoge Enang, Gonder, Mary Katherine, Sinsin, Brice
Format: Article
Language:English
Subjects:
Animal Ecology
Animal populations
Apes
Behavioral Sciences
Biomedical and Life Sciences
Chimpanzees
Conservation
Decay
Decay rate
Density
Dung
Estimates
Evolutionary Biology
Life Sciences
National parks
Nests
Original
Original Article
Pan troglodytes
Plant species
Polls & surveys
Population statistics
Rainfall
Regression analysis
Standing crop
Zoology
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Summary:Accurate assessment of great ape populations is a prerequisite for conservation planning. Indirect survey methods using nest and dung, and a set of conversion parameters related to nest decay rates, are increasingly used. Most surveys use the standing crop nest count (SCNC) method, whereby nests are counted along transects and the estimated nest density is converted into chimpanzee density using an often non-local nest decay rate. The use of non-local decay rate is thought to introduce substantial bias to ape population estimates given that nest decay rates vary with location, season, rainfall, nest shape, and tree species used. SCNC method has previously been applied in Mbam-Djerem National Park (MDNP) in Cameroon, for chimpanzee surveys using a non-local nest decay rate. This current study aimed to measure a local nest decay rate for MDNP and implications for chimpanzee population estimates in the MDNP. The mean nest decay rate estimated using a logistic regression analysis was 127 [95% CI (100–160)] days. Moreover, the results suggested that rainfall strongly influenced the nest decay rate over the early stage of the lifetime of the nests. The study confirms that estimates of chimpanzee density and abundance using non-local decay rates should be treated with caution. Our research emphasized the importance of using local nest decay rates and other survey methods which do not depend on decay rates to obtain more accurate estimates of chimpanzee densities in order to inform conservation strategies of these great apes in MDNP.
ISSN:0032-8332
1610-7365
DOI:10.1007/s10329-019-00768-3