This simulator projects a wildlife population forward year by year using the classic Leslie/Lefkovitch age-structured matrix model from population ecology. Individuals are split into four age classes — juvenile, sub-adult, adult and senior — each with its own fecundity and survival probability, tunable live with the sliders. Every simulated year the population vector is multiplied by the resulting projection matrix, and the four age-class columns rendered in 3D grow, shrink and reshuffle to match. Because the matrix is fixed each step, the age distribution provably converges to a stable shape (the dominant eigenvector) while the total population multiplies by a constant growth rate λ each year — shown live as it stabilizes, exactly the quantity ecologists compute to judge whether a population is sustainable, declining, or set to boom.