Population growth:-
The size of a population for any species is not a static parameter. It keeps changing in time, depending on various factors including food availability, predation pressure and adverse weather. Infact, it is these changes in population density that give us some idea of what is happening to the population - whether it is flourishing or declining. Whatever might be the ultimate reasons , the density of a population in a given habitat during a given period, fluctuates due to changes in four basic processes , two of which ( nativity and immigration) contribute to an increase in population density and two (mortality and emigration) to a decrease.
- Natality :- It refers to the number of births during a given period in the population that are added to the initial density.
- Mortality :- It is the number of deaths in the population during a given period.
- Immigration :- It is the number of individuals of the same species that have come into the habitat from else where during the time period under consideration.
- Emigration :- It is the number of individuals of the population who left the habitat and gone else where during the time period under consideration.
