Cm. Crockett et al., MODELING MANAGED MONKEY POPULATIONS - SUSTAINABLE HARVEST OF LONGTAILED MACAQUES ON A NATURAL HABITAT ISLAND, American journal of primatology, 40(4), 1996, pp. 343-360
Computer simulation of population dynamics can be useful in managing h
arvested populations of monkeys on islands. Between 1988 and 1991, 420
adult female and 58 adult male simian retrovirus-free Macaca fascicul
aris were released onto Tinjil Island, Indonesia, to provide the nucle
us for a free-ranging breeding colony. Natural habitat breeding facili
ties are excellent alternatives to wild trapping and compound breeding
, maximizing the health and well-being of animals destined for essenti
al biomedical research. To avoid a population crash, the number of off
spring that can be harvested annually must be based on life table char
acteristics such as age-specific natality and mortality. We used a mod
ified Leslie matrix to model changes in female population size over 26
years. First, we assumed that all 420 females were released simultane
ously and varied the annual birth rate (50%, 60%, 70%), survival rate,
and number of offspring harvested per year. Assuming high survival an
d birth rates vs. low rates, about four times as many female offspring
could be harvested annually from a stable population (87 vs. 20 offsp
ring). Terminal population size after 26 years did not differ much acr
oss rates modeled (568-696 females). Second, we modeled the number of
females actually released (including the recent addition of 42 new fem
ale breeders) and harvested (averaging 49 annually 1991-1994), and pro
jected the population through 2014. This indicated that threshold harv
est rates and terminal population sizes increased considerably over th
e first model, assuming intermediate (78 harvested, 952 females) and h
igh (152 harvested, 1,331 females) rates of survivorship and natality,
but were unchanged assuming low rates (20 harvested, 559 females). A
review of the literature and held observations on Tinjil suggest that
actual birth and survival rates resemble the intermediate values model
ed. If so, the present density on the island, projected to be similar
to 215 males and females per square kilometer, is approaching carrying
capacity. The high values are realistic upper limits. If actual survi
vorship and birth rates are at the high end of those modeled, the isla
nd's population may be on the verge of rapid expansion, requiring incr
eased harvest and provisioning. (C) 1996 Wiley-Liss, Inc.