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Estimating abundance of introduced Chinese muntjac Muntiacus reevesi and native roe deer Capreolus capreolus using portable thermal imaging equipment
Author(s) -
HEMAMI MAHMOUD R.,
WATKINSON ANDREW R.,
GILL ROBIN M. A.,
DOLMAN PAUL M.
Publication year - 2007
Publication title -
mammal review
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.574
H-Index - 76
eISSN - 1365-2907
pISSN - 0305-1838
DOI - 10.1111/j.1365-2907.2007.00110.x
Subject(s) - capreolus , roe deer , transect , distance sampling , ecology , abundance (ecology) , geography , sampling (signal processing) , environmental science , forestry , biology , physics , detector , optics
1 Managing the conservation impacts of deer requires knowledge of their numbers. However, estimating densities in forested areas is problematic, with pellet‐group‐based methods subject to error and uncertainty in estimating defecation and decay rates in addition to sampling variance. Use of thermal imaging equipment allows direct census by distance sampling. 2 Densities of introduced Chinese muntjac Muntiacus reevesi and native roe deer Capreolus capreolus were estimated in 12.8 km 2 of conifer forest in eastern England by thermal imaging distance transects. Estimated density of introduced muntjac (±95% confidence intervals [CI]: 20 ± 8 km −2 ) exceeded that of native roe deer (16 ± 6 km −2 ); 95% CI of c . 40% were achieved in 10 days of fieldwork. 3 Density estimates were not sensitive to the number of width bands applied during analysis. Detectability functions differed, with narrower effective strip widths (ESW) for muntjac (74 m) than roe deer (123 m). Thus, it is important to discriminate between species when censusing mixed assemblages. Detectability and ESW also differed among plantation growth stages. Stratification by habitat may therefore improve accuracy of density estimates but would require additional survey effort.