Proportion of deer population is given as

$$\frac{Taggeddeerincapture1}{Deerpopulation}=\frac{Taggeddeerincapture2}{Deerincapture2}$$

$$\frac{108}{Deerpopulation}=\frac{36}{54}$$

$$Deerpopulation=\frac{108\times 54}{36}=162$$