IUCN / SSC Cat Specialist Group - Digital Cat Library |
|
||||||||||
|
||||||||||
|
|
| Balme, G.A.; Hunter, L.T.B.; Slotow, R. | |
| Evaluating methods for counting cryptic carnivores | |
| 2009 Journal of Wildlife Management (73): 433-441 | |
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 cameratrapping data. Compared to our reference density (7.33 ñ 0.44 leopards/100 km2), camera-trapping generally produced more accurate but less precise estimates than did track counts. The most accurate result (6.97 ñ 1.88 leopards/100 km2) 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 ñ 1.92 leopards/100 km2) 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 ñ 1.43 leopards/100 km2) 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. |
|
 |
PDF files are only accessible to Friends of the Cat Group. Joining Friends of the Cat Group gives you unlimited access and downloads in the Cat SG Library for one year, and allows you to receive our newsletter Cat News (2 regular issues per year plus special issues). More information how to join here |
(c) IUCN/SSC Cat Specialist Group ( IUCN - The World Conservation Union) |