Abstract
Muskrat (Ondatra zibethicus) populations have been declining in North
America for decades. The precise cause of these widespread declines has
not yet been identified. Over a similar timeframe, wetlands across large
regions of North America have been experiencing an invasion of cattails
(Typha). Non-native T. angustifolia readily hybridizes with native T.
latifolia to produce T. x glauca, which tends to dominate over parental
species and other wetland plants alike. T. x glauca invasions are
associated with many negative consequences for wetlands, including a
reduction in biodiversity, open water habitat, and interspersion of
water and vegetation. Muskrats are strongly tied to wetlands, especially
where there is a high degree of interspersion of water and emergent
vegetation. Therefore, a widespread reduction in interspersion caused by
T. x glauca invasions may be contributing to widespread muskrat
population declines. We sought to understand the impact of reduced marsh
interspersion on fine-scale muskrat habitat use which will shed more
light on broad-scale population trends. We measured intensity of habitat
use by muskrats in a large, Typha-dominated marsh in south-central
Ontario using remote cameras, stratifying camera placement along a
gradient of marsh interspersion. We found no correlation between
interspersion and intensity of use, suggesting that factors other than
interspersion may drive intensity of use. Our study site, like most
marshes in the region, was highly dominated by T. x glauca. Further
research is needed to determine the impact of T. x glauca invasions on
muskrats, as well as the cause of widespread muskrat declines. Keywords:
muskrats, intensity of use, camera traps, invasive species, Typha,
wetlands