What is brood parasitism ? Explain with the help of an example.

Brood parasitism in birds is a fascinating example of parasitism.

$\Rightarrow$ In this parasitism, the parasitic bird lays its eggs in the nest of its host and let the host incubate them.

During the course of evolution, the eggs of the parasitic bird have evolved to resemble the host's egg in size and colour to reduce the chances of the host bird detecting the foreign eggs and ejecting them from the nest.