The logistic population growth is expressed by the equation

A population growing in a habitat with limited resources show initially a lag phase, followed by phases of acceleration and deceleration and finally an asymptote, when the population density reaches the carrying capacity. A plot of $\mathrm{N}$ (population density at time $t$ ) in relation to time (t) results in sigmoid curve. This type of population grown is called Verhulst-Pearl Logistic Growth and is describes by the following equation : $d N / d t=r N\left(\frac{K-N}{K}\right)$ where, $N=$ Population density at time $t$, $r=$ Intrinsic rate of natural increase $K$ = Carrying capacity Since resources for growth for most animal populations are finite and become limiting soner or later, the logistic growth model is considered a more realistic one.