A total of seven reptile species were found at Weir Farm National Historic Site during a rigorous inventory in 2000.  Included were Painted turtle (Chrysemys picta), Snapping turtle (Chelydra serpentine), Box turtle (Terrapene Carolina), and Spotted turtle (Clemmys guttata).  Also included were Common Gartersnake (Thamnophis sirtalis), Northern Water snake (Nerodia sipedon), and Northern Ring-necked snake (Diadophis punctuatus edwardsii).

Occasionally sighted along the trails and near the pond are Painted and Snapping Turtles; while Common Garter Snakes can be seen along the trails, in the hedges, or hiding among the tall grasses in the field.