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The survival equation used to estimate percent survival at

each age stage is similar to that used by Miller et al.

(1972) for the Sandhill Crane in that it combines age

independent and age dependent mortality factors.

Coefficients for adult survivorship used in the life table

are the same as those estimated by Miller et al. (1972)

for Sandhill Cranes. These had been calculated by Miller

et aj. (1972) using demographic information for the White

Stork of Europe. The life table uses a survival rate of

60% for fledging to age 1, an age independent mortality

factor of 60, and an age dependent mortality factor of

0.013 x Age. In the life table the number of individuals

surviving to each age stage is per 1,000 cohorts.


Life Equation

 A simple equation developed by Henny et al. (1970) was

used to calculate the long term average production rate

(number of female fledglings per mature female per year)

necessary to prevent a population from declining toward

extinction. The information needed for the equation was

taken from the hypothetical life table and from the

literature previously cited. Henny's life equation for a

species that does not reach sexual maturity until two or

more years after hatching, with one half breeding at that

age and all breeding at subsequent ages, is as follows:


 1 S
 b = (25)
 S SC(S + p(1-S))