Critique of density
estimation from camera-trap data
Rebecca J. Foster, Bart J. Harmsen
The Journal of Wildlife Management
Volume 76, Issue 2, pages 224–236, February
2012
Camera
trap study comes in very handy while estimating the densities
of elusive terrestrial mammals. It involves two steps.
1) Fitting conventional closed population capture–recapture
models to estimate abundance
2) Using ad hoc methods to determine the effective trapping area.
To guide wildlife management, the methodologies per se has to be accurate, robust, and
reliable.
The researchers here critically reviewed 47 published studies and
discuss the problems associated with contemporary population estimates of
elusive species from camera-trap data.
The focus was on
1)
Individual identification
2)
Sample size and capture probability
3)
Camera location and spacing
4)
The size of the study area
5)
Ad hoc density estimation from the calculation of an effective trapping
area
They also discuss the recently developed spatially explicit
capture–recapture (SECR) models as an alternative approach that does not
require the intermediate step of estimating an effective trapping area.
Here are the recommendations of the researchers
1) Greater transparency in study design and quality of the data
2) Greater rigor when reviewing manuscripts
3) More attention is to be given
to the survey design to ensure data are of sufficient quality for analysis
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