Lauren J. Livo Paul Stephen Corn 1989 Between 1978 and 1988, we recorded reproductive information from populations of ranid frogs in Colorado and Wyoming. Egg masses from five plains and montane populations of northern leopard frogs (<i>Rana pipiens</i>) contained 645-6272 eggs (x̄ = 3045, N = 68 egg masses). In two montane populations of wood frogs (<i>Rana sylvatica</i>) numbers of eggs per egg mass varied from 711-1248 (x̄ = 876, N = 15) and probably were equal to total clutch size. Mean hatching success was 90% in egg masses from one <i>R. sylvatica</i> population and ranged from 70% to 99% in <i>R. pipiens</i> egg masses. <i>Rana pipiens</i> egg masses from one location were assigned to three overlapping size distributions, which we believe reflects the underlying age structure of female frogs. application/pdf 10.2307/3536918 en Society for Northwestern Vertebrate Biology Leopard frog and wood frog reproduction in Colorado and Wyoming article