Flamingos are pink due to the presence of the pink dye canthaxanthin that they acquire through their diet.
Step-by-step explanation:
Flamingos are not born with pink feathers. Instead their feathers are grey at birth. The diet of flamingos consists of brine shrimp and blue green algae and through this diet they acquire a pink dye called canthaxanthin.
It is the presence of canthaxanthin that gives the characteristic pink color to flamingo feathers. The breakdown of carotenoid into pink pigment molecules takes place in the intestine of the flamingo by the action of enzymes and the fat deposits in the feathers, legs etc of the flamingo absorbs these pigments.