Q.What is brood parasitism? Explain with the example of the koel (Asian koel) and the crow.

Brood parasitism is a specialised form of parasitism in which one species (the brood parasite) does not build its own nest or raise its own young, but instead lays its eggs in the nest of another species (the host), leaving the host to unknowingly incubate the eggs and raise the resulting offspring. The Asian koel is the classic example: the female koel lays her egg directly in an unattended crow's nest. Remarkably, koel eggs have evolved to closely resemble crow eggs in size and colouration, which reduces the chance that the crow parents will notice and reject the foreign egg. The crow parents then incubate the koel egg alongside their own and feed the hatched koel chick as if it were their own offspring — so the crow's own reproductive effort and re …

Mention BOTH halves of the mechanism: (1) the parasite avoids the cost of nest-building/rearing, and (2) egg mimicry helps the egg go unde …

Do not describe brood parasitism as harmless to the host — the crow's own eggs/chicks are often outcompeted or neglected once the koel chick hatche …