Abstract
The muskrat (Ondatra zibethicus) is an iconic species in Canada,
valued for both its fur and its integral role in wetland ecosystems, and
widely regarded for its perseverance. However, the resilience of this
semi-aquatic mammal seems to be in question now as increasing evidence
points to widespread population declines. Recent analyses of harvest
data across North America suggest a reduction in their numbers, but this
has not been widely corroborated by population surveys. In this study we
replicated historic muskrat house count surveys at two large Great Lakes
coastal wetlands and present confirmation that declines in muskrat
harvest correspond to actual declines in muskrat abundance. At the Point
Pelee National Park marsh and the Matchedash Bay-Gray Marsh wetland we
found that mean muskrat house counts declined by 93% and 91%
respectively between historic surveys 40-50 years ago and contemporary
surveys over the past five years. The factors responsible for these
dramatic declines remain unclear but there may be a relationship with
changes in the habitat quality of these wetlands that have occurred over
the same time frame. Not only is the loss of muskrats an issue for the
resulting loss of the wetland ecosystem services they provide, but it
may be an indication of broader marsh ecosystem degradation. As such, a
scarcity of muskrats should be considered a red flag for the state of
biodiversity in our wetlands. Continued surveys and ongoing research are
needed to shed more light on the current status of muskrat populations
and their marsh habitats across their native range. Keywords: Fur
harvest; Muskrat; Ondatra; Population decline; Typha;
Wetlands