Indian Elephant Population in Thailand

Problem definition

During the course of the 20th century, the population of indian elephants has decreased drastically, mostly due to a significant reduction of elephants' natural habitat, as well as decrease in utilization of elephants in logging industry and shift to a role of a tourist attraction. This model showcases the evolution of elephants' population in Thailand for upcoming 100 years.

Method

The vensim modelling tool was selected for the purpose of this simulation.

Model

Model variables

Population

Number of elephants in Thailand. Starting value is 8900 . This is the variable that we are examining.

Increase

Number of elephants that are born
=Natality*Population

Decrease

Number of elephants that have died
=Mortality*Population

Natality

Ratio of newly born elephants to elephant population. Amount of newborn elephants equals fertility multiplied by number of females in reproductive age divided by 40*2 (number of reproductive years, multiplied by 2 as elephants pregnancy takes 22-24 months). We then multiply by Governement regualtion ratio.
=((Fertility*((Ratio of females*Population)*Ratio of females in reproductive age)/80)*Government regulations)/Population

Fertility

Amount of calves a female is able to have during her reproductive lifespan. 40% of elephants' population lives in wilderness and the fertility is not affected by stress therefore a wild female is able to have 10 calves, and semi-domesticated female is able to have 7 calves during her life.
=0.4*10+0.6*7

Ratio of females in reproductive age

Elephant female can have calves during her 15 to 50 years.
=0.5714

Ratio of females

Ratio of females on elephants' population
=0.53476

Government regulation

Index of government regulations <0;1>, 1 means no government regulation
=1

Mortality

Ratio of dead elephants on the elephants' population.
=((Population/Average lifespan) + Unnatural deaths)/Population

Average lifespan

=70

Unnatural deaths

Number of deaths that do not happen naturally.
=((Deaths by improper handling ratio*Population)+(Poaching ratio*Population))*Government regulations + Population*Deforestation ratio

Deaths by improper handling ratio

Ratio of deaths that happen due to unhuman behavior towards elephants and conditions they have to live in.
=0.01685

Poaching ratio

Ratio of deaths that happen because of elephants being hunted either for skin, tusks or to capture young calve.
=3.3e-05

Deforestation ratio

Ratio of deforastation in Thailand, this has a close correlation to number of elephants as this the major factor affecting the population.
=0.0035

Results

As we can see, we can expect a continuous decrease in elephants' population in Thailand. By the year 2119 the elephants' population in Thailand should decrease by 2492 elephants.

Conclusion

In this simulation I created a functional model representing the evolution of elephants' population in Thailand. The results show continuous decrease over the course of following 100 years. However there is a room for improvements, like parameter deforestation ratio because nowadays the problem of deforestation is gaining on significance in general public eyes and this might lead into deforestation ratio decrease and potentially lead into elephants' population growth. In addition, also the pressure from general public as well as organizations like WWF might lead into more strict government regulations.

Code

File:Elephant population.mdl