3.1 Point Pelee Marsh
We found very low numbers of muskrat houses at Pelee over our four
contemporary survey years between 2014-2019 as compared to the historic
survey period from 1968-1980 (Fig. 3). The mean (SE) number of muskrat
houses found at Pelee between 1968 and 1980, excluding incomplete survey
zones and years, was 719 (202.9). The 95% confidence interval for house
counts during these years was 267 to 1171. In contrast, we observed a
mean (SE) house count of 47 (7.4) during 2014-2019, excluding the same
zones as we did with the historic data set. The 95% confidence interval
for the house counts during these latter years was 24 to 71.
Our contemporary surveys of Pelee represent a 93% decline in mean
muskrat abundance from historic levels 40-50 years prior (Fig. 4).
Retaining the count results for the excluded survey zones still resulted
in a dramatic difference in the mean number of houses found between each
survey period (791 historically vs. 80 recently) and a 90% decline in
house numbers.