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A. Status of the Spectacled Eider - U.S. Fish and Wildlife Service

A. Status of the Spectacled Eider - U.S. Fish and Wildlife Service

A. Status of the Spectacled Eider - U.S. Fish and Wildlife Service

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decline, by far <strong>the</strong> fastest way to recovery is to increase adult survival. Therefore, efforts<br />

should be made to reduce predation (human or o<strong>the</strong>rwise) on adults. To get equivalent results<br />

in increasing population growth by increasing juvenile survival will require enormous<br />

reductions in juvenile mortality.<br />

‘U<br />

0.1<br />

~O06<br />

0<br />

zO.04<br />

‘U<br />

E<br />

4<br />

~O. 02<br />

C.)<br />

z<br />

0 JUVENILE SURViVAL ADULT SURVIVAL FERTILITY<br />

PARAMETERS OF CHANGE<br />

Figure rn-b. Results <strong>of</strong> a demographic sensitivity analysis. Given a stable population (r = 0),<br />

<strong>the</strong> results give <strong>the</strong> population growth rate that would result from a 10% increase in: juvenile<br />

survival only, adult survival only, <strong>and</strong> fertility only. Growth rates are most sensitive to changes in<br />

adult survival rates: a 10% increase in adult survival results in about an 8% increase in population<br />

growth. An equivalent increase in juvenile survival rate results in

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