Remarkable Male Bias in a Population of Midland Painted Turtles (Chrysemys picta marginata) in Ontario, Canada

We report on male sex bias in a population of Midland Painted Turtle (Chrysemys picta marginata) at a wetland near Brampton, Ontario, Canada. The wetland is bisected by a major arterial road and characterized by high traffic volume and substantial wildlife-vehicle collisions. Road mortality surveys conducted in 2011, 2013, and 2015 documented 217 dead turtles, of which 118 could positively be identified as Midland Painted Turtle. From 2014–2015, we conducted a mark-recapture survey and captured 34 individual Midland Painted Turtles. The male:female sex ratio of 21:4 is one of the most skewed sex ratios for this species on record. We attribute this skew to sex-specific road mortality amongst other possible factors such as predation and nesting conditions. This study adds to the general body of work that has found a male sex ratio bias in areas of high road mortality.