On driftwood lying on the sand of Pelee's east beach. This looks similar to the image of Ammodonus fossor
taken from this page
at U. of Wisconsin. The species isn't listed on the 1991 Checklist of Beetles of Canada and Alaska ( 1
) but may have been recorded in Canada since that time (?). A PDF doc
says A. fossor is a flightless beetle living in isolated sandy habitats in scattered localities from Texas to Wisconsin and Ohio, eastward to New York and the Carolinas.
(Update: Pat Bouchard of Agriculture Canada confirmed the ID and said it was the first record of this species in Canada. I've suggested a common name based on the meaning of the species epithet)