“from the very childhood I used to hear stories about birds and their kids from my grandma……She used to tell me that
cuckoos usually lay eggs in the nests of crows …so I am going to present the actual phenomenon of this very interesting
happening; this is in a nutshell termed as Brood Parasitism.”
Parasitism is a non-mutual symbiotic relationship between species, where one species, the parasite is benefitted at the expense of the other, the host. Unlike predators, parasites typically do not kill their host, though they are found to be much smaller than their host. Brood parasites are organisms that use the strategy of “BROOD PARASITISM”; it is found among birds, fish or insects involving the manipulation and use of host individuals (unknowingly for the host) either the same or different species for bringing up the young of the brood parasite. We take the example of cuckoo here. The female cuckoo consciously laid eggs in the nest made by crow. A cuckoo egg usually closely mimics the eggs of the host (crow eggs) .The host may recognise the intruding egg and abandon the nest or it may incubate and hatch the cuckoo egg.
Shortly after hatching, the young cuckoo using a scoop-like depression on its back; instinctively shoves over the edge of the nest anysolid object that it comes in contact with. With the disappearance of their own eggs and the rightful young, the foster parents devote the totalcare to the young cuckoos for their upbringing .One of the tragicomic scenes in nature is a pair of small foster parents to keep up with the voracious appetite of an outsized young one. Only about 40 % of cuckoo species worldwide are BROOD PARASITES, and the rest of the species care for their own egg & young.The brood parasitism is not restricted to females of one species laying eggs in the nest of the other species. In addition to some of our cuckoos, females of a wide variety of species lay eggs in the nests of other females of the same species also. Brood Parasitism is much less common in the other groups of birds. It is observed among four percent of bird species; including the member of such diverse groups like DUCKS, WEAVERS, & COWBIRDS.
By INDRANI BANERJEE CHAITAK Vol-2/February 2015