Table 1

The parameters in the ecological model (equations 1–3) were estimated from the survey data of the Southern and Northern areas using the Gibbs sampler as implemented in bugs, version 0.6 (22, 34)

ParameterSouthern area Northern area
Estimate95% ciEstimate95% ci
αconst2.73{2.72, 2.74}2.13{2.12, 2.15}
2.58{2.32, 2.84}1.93{1.59, 2.27}
σα21.12{0.79, 1.59}0.63{0.48, 0.84}
β−0.26{−0.31, −0.21}−0.22{−0.26, −0.17}
γ−0.06{−0.09, −0.02}−0.07{−0.11, −0.04}
c−0.58{−0.91, −0.26}−0.39{−0.71, −0.06}
λFixed at 0.4N/A
  • A Poisson error was assumed for the counts of the 0- and 1-groups. Annual adult survival, λ, was fixed at 0.4. The reproductive parameter, α, was either assumed to be constant (αconst) or randomly distributed with variance, σα2, around a time-invariant mean, ᾱ. The parameters for intracohort (β) and intercohort (γ) density dependence and basal survival (c) were assumed to be time invariant. All parameters were assigned noninformative priors (22, 34). Estimates and 95% ci were based on 100,000 iterations of the Gibbs sampler after a burn-in of 10,000 iterations. N/A, not applicable.