A comparison of density estimation methods for monitoring marked and unmarked animal populations

These data were generated to compare different methods of estimating
population density from marked and unmarked animal populations. We compare
conventional live trapping with two more modern, non-invasive field
methods of population estimation: genetic fingerprinting from hair-tube
sampling and camera trapping for the European pine marten (Martes martes).
We used arrays of camera traps, live traps, and hair tubes to collect the
relevant data in the Ring of Gullion in Northern Ireland. We apply marked
spatial capture-recapture models to the genetic and live trapping data
where individuals were identifiable, and unmarked spatial
capture-recapture (uSCR), distance sampling (CT-DS), and random encounter
models (REM) to the camera trap data where individual ID was not possible.
All five approaches produced plausible and relatively consistent point
estimates (0.41 – 0.99 animals per km2), despite differences in precision,
cost, and effort being apparent. In addition to the data, we provide novel
code for running unmarked spatial capture-recapture (uSCR) and random
encounter models (REM) to the camera trap data where individual ID was not
possible.