Amboseli Elephant Life Tables

Thu, 2010-10-07 13:28 by pili · Forum/category:

The Amboseli elephants comprise one of the few populations of free-living large mammals in the world for which there are complete and accurate life table data.

Life tables are a way of viewing the probabilities of death for elephant males and females at different ages. Here, we provide standard life tables from survival analysis in 5 year bins for all known deaths (n = 407 females, 534 males), and a second table excluding the cases where we know that humans were involved in the death (spearing, poaching, poisoning, or where other human activities caused the death).
Each life table shows out of the number of individuals born, the number that died in each five year period (number of terminal events), and those that survived (proportion surviving) . Individuals whose fate can not be determined are “withdrawn”. The survival analysis also predicts the “hazard” of death for individuals within each age group. The “Std Error” provides a statistical estimate of the precision of the values. The tables presented below are one more example of the unique contribution of ATE to the science base of elephant conservation.

Life Tables: all deaths
Sex Interval Start Time Number Entering Interval Number Withdrawing during Interval Number Exposed to Risk Number of Terminal Events Proportion Terminating Proportion Surviving Cumulative Proportion Surviving at End
of Interval
Std. Error of Cumulative Proportion
Surviving at End of Interval
Probability Density Std. Error of Probability Density Hazard Rate Std. Error of Hazard Rate
Female 0 1244 169 1159.500 186 .16 .84 .84 .01 .032 .002 .03 .00
5 889 173 802.500 12 .01 .99 .83 .01 .003 .001 .00 .00
10 704 116 646.000 15 .02 .98 .81 .01 .004 .001 .00 .00
15 573 85 530.500 25 .05 .95 .77 .01 .008 .001 .01 .00
20 463 76 425.000 24 .06 .94 .73 .02 .009 .002 .01 .00
25 363 86 320.000 31 .10 .90 .66 .02 .014 .002 .02 .00
30 246 12 240.000 21 .09 .91 .60 .02 .011 .002 .02 .00
35 213 40 193.000 19 .10 .90 .54 .02 .012 .003 .02 .00
40 154 47 130.500 24 .18 .82 .44 .03 .020 .004 .04 .01
45 83 17 74.500 12 .16 .84 .37 .03 .014 .004 .04 .01
50 54 4 52.000 16 .31 .69 .26 .03 .023 .005 .07 .02
55 34 1 33.500 9 .27 .73 .19 .03 .014 .004 .06 .02
60 24 4 22.000 7 .32 .68 .13 .03 .012 .004 .08 .03
65 13 4 11.000 5 .45 .55 .07 .02 .012 .005 .12 .05
70 4 3 2.500 1 .40 .60 .04 .03 .006 .005 .10 .10
Male 0 1211 176 1123.000 221 .20 .80 .80 .01 .039 .002 .04 .00
5 814 171 728.500 33 .05 .95 .77 .01 .007 .001 .01 .00
10 610 102 559.000 29 .05 .95 .73 .01 .008 .001 .01 .00
15 479 73 442.500 63 .14 .86 .62 .02 .021 .002 .03 .00
20 343 64 311.000 52 .17 .83 .52 .02 .021 .003 .04 .01
25 227 39 207.500 36 .17 .83 .43 .02 .018 .003 .04 .01
30 152 8 148.000 30 .20 .80 .34 .02 .017 .003 .05 .01
35 114 15 106.500 27 .25 .75 .26 .02 .017 .003 .06 .01
40 72 16 64.000 15 .23 .77 .20 .02 .012 .003 .05 .01
45 41 12 35.000 16 .46 .54 .11 .02 .018 .004 .12 .03
50 13 3 11.500 3 .26 .74 .08 .02 .006 .003 .06 .03
55 7 2 6.000 2 .33 .67 .05 .02 .005 .003 .08 .06
60 3 0 3.000 2 .67 .33 .02 .02 .007 .004 .20 .12
65 1 0 1.000 1 1.00 .00 .00 .00 .003 .003 .40 .00



Life Table: Natural mortality only
Sex Interval Start Time Number Entering Interval Number Withdrawing during Interval Number Exposed to Risk Number of Terminal Events Proportion Terminating Proportion Surviving Cumulative Proportion Surviving at End
of Interval
Std. Error of Cumulative Proportion
Surviving at End of Interval
Probability Density Std. Error of Probability Density Hazard Rate Std. Error of Hazard Rate
Female 0 1096 169 1011.500 160 .16 .84 .84 .01 .032 .002 .03 .00
5 767 173 680.500 9 .01 .99 .83 .01 .002 .001 .00 .00
10 585 116 527.000 7 .01 .99 .82 .01 .002 .001 .00 .00
15 462 85 419.500 14 .03 .97 .79 .01 .005 .001 .01 .00
20 363 76 325.000 3 .01 .99 .78 .01 .001 .001 .00 .00
25 284 86 241.000 11 .05 .95 .75 .02 .007 .002 .01 .00
30 187 12 181.000 9 .05 .95 .71 .02 .007 .002 .01 .00
35 166 40 146.000 8 .05 .95 .67 .02 .008 .003 .01 .00
40 118 47 94.500 9 .10 .90 .61 .03 .013 .004 .02 .01
45 62 17 53.500 4 .07 .93 .56 .03 .009 .004 .02 .01
50 41 4 39.000 10 .26 .74 .42 .05 .029 .008 .06 .02
55 27 1 26.500 7 .26 .74 .31 .05 .022 .008 .06 .02
60 19 4 17.000 3 .18 .82 .25 .05 .011 .006 .04 .02
65 12 4 10.000 4 .40 .60 .15 .05 .020 .009 .10 .05
70 4 3 2.500 1 .40 .60 .09 .06 .012 .010 .10 .10
Male 0 1002 176 914.000 194 .21 .79 .79 .01 .042 .003 .05 .00
5 632 171 546.500 22 .04 .96 .76 .01 .006 .001 .01 .00
10 439 102 388.000 17 .04 .96 .72 .02 .007 .002 .01 .00
15 320 73 283.500 31 .11 .89 .64 .02 .016 .003 .02 .00
20 216 64 184.000 17 .09 .91 .58 .02 .012 .003 .02 .00
25 135 39 115.500 11 .10 .90 .53 .03 .011 .003 .02 .01
30 85 8 81.000 10 .12 .88 .46 .03 .013 .004 .03 .01
35 67 15 59.500 7 .12 .88 .41 .03 .011 .004 .03 .01
40 45 16 37.000 4 .11 .89 .36 .04 .009 .004 .02 .01
45 25 12 19.000 4 .21 .79 .29 .04 .015 .007 .05 .02
50 9 3 7.500 1 .13 .87 .25 .05 .008 .007 .03 .03
55 5 2 4.000 1 .25 .75 .19 .07 .012 .011 .06 .06
60 2 0 2.000 2 1.00 .00 .00 .00 .037 .013 .40 .00