Reproductive frequency in captive and wild-caught female of Tiliqua nigrolutea was examined over five consecutive reproductive seasons. Reproductive frequency (0.38 +/- 0.035) was clearly different from an annual pattern of 1.0 (i.e. all females reproducing every year). Individual females did not reproduce every year, but skipped " seasons were staggered such that a proportion of the population produced a clutch each season. Skipped reproductive opportunities are attributed to a combination of a long gestation high relative clutch mass (0.43 +/- 0.034) parturition late in the active season a cessation of feeding in the latter stages of gestation and low autumn temperatures limiting post-partum feeding opportunities."