The eastern massasauga rattlesnake (Sistrurus catenatus) relies on small-scale differences in peatland surface elevation to survive harsh overwintering conditions at the northern limit of its range. We characterized the spatial heterogeneity of surface topography in peatlands within the eastern Georgian Bay rock barrens landscape of Ontario, Canada, to assess available snake overwintering habitat. At six peatlands, we used a differential global positioning system to collect surface-elevation data. We created spatially-explicit surface models to map peatland surface topography, quantify habitat that was likely to remain unflooded during the overwintering period, and identify key characteristics associated with greater habitat availability. While surface elevations were spatially heterogeneous within and among sites, larger peatlands were associated with greater surface spatial variability relative to the lowest elevation measured within each site. However, even peatlands with very little spatial heterogeneity (average of 0.24 m above lowest elevation), provided unflooded overwintering habitat. Inter-annual weather conditions and peatland and watershed characteristics likely control the availability and distribution of unflooded overwintering habitat. We found that trees, specifically white pine (Pinus strobus) and maple (Acer spp.), were spatially associated with higher surface elevations and could be used to identify areas of unflooded winter habitat. Our findings are useful for landscape-scale assessments of available overwintering habitat to prioritize conservation and management efforts.

东部马萨萨加响尾蛇（Sistrurus catenatus）依靠泥炭地表面高度的小范围差异，以在其范围的北限度过严酷的越冬条件。我们表征了加拿大安大略省乔治亚湾东部岩石贫瘠的景观中泥炭地的表面地形空间异质性，以评估可用的蛇越冬栖息地。在六个泥炭地，我们使用了差分全球定位系统来收集地表高程数据。我们创建了空间明晰的表面模型，以绘制泥炭地表面地形图，量化在越冬期间可能仍未淹没的生境，并确定与更大的生境可用性相关的关键特征。尽管站点内和站点之间的表面高程在空间上是异质的，相对于每个站点内测得的最低海拔，较大的泥炭地与较大的表面空间变异性相关。但是，即使泥炭地的空间异质性很小（平均最低海拔之上0.24 m），也提供了未淹没的越冬栖息地。年际天气状况，泥炭地和流域特征可能会控制未淹没的越冬栖息地的可用性和分布。我们发现树木，特别是白松树（樟子松和枫树（Acer spp。）在空间上与较高的海拔高度相关联，可用于识别未淹没的冬季栖息地区域。我们的发现可用于对可用的越冬栖息地进行景观规模评估，从而优先进行保护和管理工作。