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Diefenbach, D.R.; Conroy, M.J.; Warren, R.J.; James, W.E.; Baker, L.A.; Hon, T.
A test of the scent-station survey technique for bobcats
1994  Journal of Wildlife Management (58): 10-17

Scent-station surveys have been widely used to monitor Boat _(Lynx rufus_) populations. But relationships between bobcat abundance and the index derived from scent-station surveys have not been validated. In autumn 1988 and 1989 we reintroduced bobcats (n = 31) to Cumberland Island. Georgia. We conducted 15 scent-station surveys during September-February 1988. 1989, and 1990 to obtain scent station indices (SSI) as we increased bobcat density. We found a positive relationship (+ = 0.45. _P _= 0.0066) between population size and SSI. However, because SSI variance also was correlated positively with SSI. We transformed data to meet the assumption of homoscedasticity for the regression model (r2 = 0.73. _P _< 0.001). Predictions of population size using individual scent-station surveys had poor precision. Analysis of statistical power indicated that 4 replicate scent-station surveys had an _8O%* _probability of detecting only large (>22.5%) changes in populations of high density _(0.5 _bobcats/km'). We recommend that (1) multiple scent-station surveys be conducted each year to monitor changes in bobcat populations: (2) SSI values should be calculated as proportions and transformed to reduce heteroscedasticity); (3) each stratum in a sampling design should contain as many stations as possible to minimize the problem of discrete data (110. of visits) analyzed as a continuous variable (proportion of stations visited); (4) scent stations should be placed as far apart us logistically feasible to minimize multiple visits by individual bobcats; and _(5) _results of the. power analysis should be used as a minimum guideline for estimating sample-size requirements.

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