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Density Estimates of Two Endangered Nocturnal Lemur Species From Northern M adagascar: New Results and a Comparison of Commonly Used Methods
Author(s) -
MEYLER SAMUEL VIANA,
SALMONA JORDI,
IBOUROI MOHAMED THANI,
BESOLO AUBIN,
RASOLONDRAIBE EMMANUEL,
RADESPIEL UTE,
RABARIVOLA CLÉMENT,
CHIKHI LOUNES
Publication year - 2012
Publication title -
american journal of primatology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.988
H-Index - 81
eISSN - 1098-2345
pISSN - 0275-2565
DOI - 10.1002/ajp.21997
Subject(s) - distance sampling , endangered species , nocturnal , lemur , sampling (signal processing) , transect , population size , population , population density , mark and recapture , ecology , biology , statistics , habitat , mathematics , demography , physics , detector , sociology , primate , optics
Very little information is known of the recently described M icrocebus tavaratra and L epilemur milanoii in the D araina region, a restricted area in far northern M adagascar. Since their forest habitat is highly fragmented and expected to undergo significant changes in the future, rapid surveys are essential to determine conservation priorities. Using both distance sampling and capture–recapture methods, we estimated population densities in two forest fragments. Our results are the first known density and population size estimates for both nocturnal species. In parallel, we compare density results from four different approaches, which are widely used to estimate lemur densities and population sizes throughout M adagascar. Four approaches ( K ing, K elker, M uller and B uckland) are based on transect surveys and distance sampling, and they differ from each other by the way the effective strip width is estimated. The fifth method relies on a capture–mark–recapture ( CMR ) approach. Overall, we found that the K ing method produced density estimates that were significantly higher than other methods, suggesting that it generates overestimates and hence overly optimistic estimates of population sizes in endangered species. The other three distance sampling methods provided similar estimates. These estimates were similar to those obtained with the CMR approach when enough recapture data were available. Given that M icrocebus species are often trapped for genetic or behavioral studies, our results suggest that existing data can be used to provide estimates of population density for that species across M adagascar. Am. J. Primatol. 74:414‐422, 2012. © 2012 Wiley Periodicals, Inc.