Family of curves used to model annual apparent survival as a function of age in the Φ(curve) models.

<p>The models follow the equations, , where κ represents adult survival (κ = 0.98 in curves shown here) and σ controls the speed at which adult survival is attained. Curves where σ<1.0 fit the data best, indicating survival plateaued at a young age, compared with σ = 3.0 where survival plateaus at around age 8.