IUCN / SSC Cat Specialist Group - Digital Cat Library |
|
||||||||||
|
||||||||||
|
|
| Rowcliffe, J.M.; Kays, R.; Carbone, C.; Jansen, P.A. | |
| Clarifying assumptions behind the estimation of animal density from camera trap rates | |
| 2013 The Journal of Wildlife Management (77): 876-876 | |
Foster and Harmsen (2012) presented a useful review of density estimation from camera trap data, concluding with an important all for increased rigor and transparency in study design. Although most of their review focuses on mark-recapture and mark-resight analyses, they also briefly critique a recent effort to estimate density of species that cannot be recognized individually, the random encounter model (REM; Rowcliffe et al. 2008). Here, we explain that this critique follows from a misrepresentation of sources of bias in the REM. First, Foster and Harmsen (2012) state that the REM assumes that animals move randomly and independently of one another. This assumption was mathematically convenient to derive a formula linking density with trap rate (Rowcliffe et al. 2008). However, Hutchinson and Waser (2007) demonstrated analytically that violations of this assumption do not bias expected contact rates as a function of density, and Rowcliffe et al. (2008) provided empirical evidence that field results are also unbiased in practice. Thus, the REM is not sensitive to nonrandom or non-independent movement of animals. |
|
 |
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) |