INFLOWS:
TIME_3 ¼ TWO_YEAR_OLDSÀDIE_2 {Net graduation of the two year olds to
adulthood. Individuals per Time Period}
OUTFLOWS:
DIE_3 ¼ ADULTS * PRELIM_FRAC_DIE {Individuals per Time Period}
CALVES(t) ¼ CALVES(t À dt) + (BIRTHS À TIME_1 À DIE_0) * dt
INIT CALVES ¼ 3640 {Individuals}
INFLOWS:
BIRTHS ¼ (BETA * TWO_YEAR_OLDS + B * ADULTS) * .7 {.7 is the fraction
of the adult population which is female. Fecundity is greater among the adults.
Individuals per Time Period}
OUTFLOWS:
TIME_1 ¼ CALVES À DIE_0 {Individuals per Time Period}
DIE_0 ¼ (1 - Q) * (CALVES) {The survival rate q improves with time, reducing
the death rate of the calves. Individuals per Time Period}
TWO_YEAR_OLDS(t) ¼ TWO_YEAR_OLDS(t À dt) + (TIME_2 À TIME_3 À
DIE_2) * dt
INIT TWO_YEAR_OLDS ¼ 1680 {Individuals}
INFLOWS:
TIME_2 ¼ YEARLINGSÀDIE_Y {The net number of yearlings graduating to two
year olds. Individuals per Time Period}
OUTFLOWS:
TIME_3 ¼ TWO_YEAR_OLDSÀDIE_2 {Net graduation of the two year olds to
adulthood. Individuals per Time Period}
DIE_2 ¼ TWO_YEAR_OLDS * PRELIM_FRAC_DIE {Individuals per Time
Period}
YEARLINGS(t) ¼ YEARLINGS(t À dt) + (TIME_1 À TIME_2 À DIE_Y) * dt
INIT YEARLINGS ¼ 2240 {Individuals}
INFLOWS:
TIME_1 ¼ CALVES À DIE_0 {Individuals per Time Period}
OUTFLOWS:
TIME_2 ¼ YEARLINGSÀDIE_Y {The net number of yearlings graduating to two
year olds. Individuals per Time Period}
DIE_Y ¼ YEARLINGS * PRELIM_FRAC_DIE {Individuals per Time Period}
B ¼ .92 {Given adult female fecundity. Births per Female}
BETA ¼ .3 {Given two year old female fecundity. Births per Female}
NONCALF_POP ¼ YEARLINGS + TWO_YEAR_OLDS + ADULTS
PRELIM_FRAC_DIE ¼ WB_DIE/NONCALF_POP {A death rate assumed to
apply to yearlings, two year olds and adults. Individuals per Individuals per
Time Period}
TOTAL_WB ¼ CALVES+NONCALF_POP {Individuals}
WB_DIE ¼ ( WB_PER_LION * LIONS + CROPPING * 1) {The number of wildebeest eaten and shot in the game park per year.}
31.2 Wildebeest Model Equations
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