Fate of 150 Year Old Beaver Ponds in the Laurentian Great Lakes Region

The North American beaver, Castor canadensis, has recovered from historic overtrapping, recolonizing much of its former range as its population expanded. Previous studies using historical aerial photos document recent increases in number of beaver ponds, but the long-term sustainability of beaver populations and their ponds over centuries of landscape alteration is unknown. This paper analyzes the fate of beaver ponds mapped in 1868 near Ishpeming, Michigan, USA. Of the 64 beaver dam and pond sites mapped in the 1860s, 72 % were still discernible in 2014. Land use changes that altered the terrain (mining, residential development) or stream paths (channelization) were the main sources of beaver pond loss. This remarkable consistency in beaver pond placement over the last 150 years is evidence of the beaver’s resilience.