Spatio-temporal patterns of mink and muskrat in Canada during a quarter century

1. Fur-return data on muskrat (Ondatra zibethicus) and mink (Mustela vison) from 80 posts of the Hudson's Bay Company were analysed. From each post we obtained the number of furs bought from trappers during 25 years (1925-49) . 2. The ecological information content of the data was assessed using questi onnaires sent to each post. We conclude that fur-return data reflect relati ve abundance of muskrat and mink, and not primarily information about the t rappers. 3. The most-common temporal pattern of the two species are cycles with a pe riod of 8-9 years, with muskrat cycling 1-2 years ahead of the mink. This p attern, as would be expected in a typical predator-prey relationship, is fo und throughout the boreal forest region, with the exception of several post s in eastern Canada. In the eastern region, the two species were found to f luctuate in synchrony. 4. The data show broad-scale synchrony. Peaks (and troughs) are roughly ali gned in phase over the entire Canadian boreal forest. 5. In some areas the phase of the cycle is either ahead or behind the avera ge cycle. Peaks (and troughs) of mink and muskrat cycles generally appear f irst in the Athabasca Basin region (for mink in the Hudson's Bay region of Manitoba and Ontario) and from this epicentre spread throughout Canada with in 2-3 years. 6. Synchrony (i.e. mean correlation) declines with distance; for distances less than 450 km, similarity among populations is higher than the average.