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Evaluating Methods for Counting Cryptic Carnivores
Author(s) -
BALME GUY A.,
HUNTER LUKE T. B.,
SLOTOW ROB
Publication year - 2009
Publication title -
the journal of wildlife management
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.94
H-Index - 111
eISSN - 1937-2817
pISSN - 0022-541X
DOI - 10.2193/2007-368
Subject(s) - camera trap , panthera , leopard , carnivore , mark and recapture , estimator , population , geography , statistics , population density , distance sampling , abundance (ecology) , ecology , mathematics , predation , biology , demography , sociology
ABSTRACT Numerous techniques have been proposed to estimate carnivore abundance and density, but few have been validated against populations of known size. We used a density estimate established by intensive monitoring of a population of radiotagged leopards ( Panthera pardus ) with a detection probability of 1.0 to evaluate efficacy of track counts and camera‐trap surveys as population estimators. We calculated densities from track counts using 2 methods and compared performance of 10 methods for calculating the effectively sampled area for camera‐trapping data. Compared to our reference density (7.33 ± 0.44 leopards/100 km 2 ), camera‐trapping generally produced more accurate but less precise estimates than did track counts. The most accurate result (6.97 ± 1.88 leopards/100 km 2 ) came from camera‐trap data with a sampled area buffered by a boundary strip representing the mean maximum distance moved by leopards outside the survey area (MMDMOSA) established by telemetry. However, contrary to recent suggestions, the traditional method of using half the mean maximum distance moved from photographic recaptures did not result in gross overestimates of population density (6.56 ± 1.92 leopards/100 km 2 ) but rather displayed the next best performance after MMDMOSA. The only track‐count method comparable to reference density employed a capture‐recapture framework applied to data when individuals were identified from their tracks (6.45 ± 1.43 leopards/100 km 2 ) but the underlying assumptions of this technique limit more widespread application. Our results demonstrate that if applied correctly, camera‐trap surveys represent the best balance of rigor and cost‐effectiveness for estimating abundance and density of cryptic carnivore species that can be identified individually.