c2011 (S)
About thirty years ago, a friend and I were kayaking on Lambton County's Bear Creek a couple of kilometres upstream from Wilkesport. We saw a very large snake swimming on the creek nearby. It looked to be four or five feet long, and we wondered if it might be a Timber or Massasauga Rattler. I remember the distinct markings on that snake, and it fits into the proper range, etc. One possibility would be the northern water snake, which gets up to 135-140 centimetres in length.
http://canadianbiodiversity.mcgill.ca/english/species/herps/herppages/Ner_sip.htm
The only other possibility that I am aware of, and it's an even bigger animal, would be the Grey Ratsnake.
While there are no recent or historical sightings in Lambton County, Bear Creek is only twenty or thirty miles from areas of reported sightings. It's the same Carolinian habitat, and the temperature ranges, and available prey animals are similar. So it's not entirely out of the question. The real problem with snakes is that they are often communal breeders. Once a colony has been wiped out, it could be decades or centuries before another is established. All these years later, I guess we'll never know what kind of a snake we saw, but a new species for the area was discovered a decade ago. That was some kind of poplar tree more common to the Ohio valley and elsewhere. The Gray rat snake can get up to anywhere from 1.7 to 2.0 metres in length.
http://nature.ca/notebooks/english/brsnake_p0.htm
