In any case, I imagine the female cuckoos have already placed their eggs in the nests of other birds. If they haven't, I suspect they will do so very shortly. Apparently, a female cuckoo will place its egg in the nest of the species that reared the female cuckoo itself. Thus, if a female cuckoo was reared by sparrows, it will inevitable place its egg in a sparrow's nest.
Cuckoos are notorious brood parasites, but the behavior of the cuckoo chick after it hatches is truly something to behold. Immediately after hatching, the cuckoo chick systematically eliminates whatever competition it happens to find. If it hatches early enough, it pushes the other eggs out of the nest (as the short video below shows). If it hatches at the same time as or slightly later than the host hatchlings, it will doggedly eject its step brothers and sisters from the nest until none remain, thereby ensuring that it alone will be the sole beneficiary of its hosts incessant feeding.
The cuckoo chick in the video reminded me of Sisyphus; however, unlike Sisyphus, the cuckoo chick's efforts ultimately proved fruitful, at least for it.