Temporal trends in tuatara population sex ratio on North Brother Island.

<p>We find an increasing male-biased trend in the adult sex ratio both using the count ratio directly from the number of individuals captured in each survey (1988–2012; black circles) and using an abundance ratio corrected for detection probability from the mark-recapture results (1988–2011; open triangles). The dashed line indicates the linear trend in the abundance ratio. Error bars on the abundance ratio data are ±1 SE calculated using the delta method.