Gadagkar, Raghavendra and Kolatkar, Milind (1996) Evidence for Avian mafia! In: Current Science, 70 (2). pp. 115-117.
An unwritten rule in evolutionary biology is that anything that can evolve will evolve. Birds are remarkable for their extraordinary effort at nest building and brood care. Given that so many species of birds spend so much time and effort at these activities, there is plenty of room for some species to take it easy, lay their eggs in the nests of other species and hitch-hike on their hosts. The cuckoo that lays its eggs in the nests of a variety of host species is well known. Indeed, over 80 species, i.e. over 1% of bird species are known to be such obligate inter-specific brood parasites. These include two-sub-families of cuckoos, two types of finches, the honey-guides, the cowbirds and the black-headed $duck^1$. Because parasite species often use more than one host species, many more than 1% of bird species act as hosts to brood parasites. Interspecific brood parasitism has evolved independently at least seven times in birds and can have a significant effect on the populations of the host species and even lead to their extinction. Although hosts sometimes detect and eject alien eggs, their success in ridding their nests of parasite eggs is often very limited and that is why brood parasitism has survived as a way of life. One reason for such limited success of the hosts is the often exquisite mimicry on the part of the parasites whose eggs are virtually indistinguishable from those of the host1. What is perplexing, however, is that many parasite species lay eggs that look nothing like their host's eggs and yet get away with it. Obviously hosts have not perfected the art of removing all or most of the alien eggs. But why should this be so?
|Item Type:||Journal Article|
|Additional Information:||Copyright of this Article belongs to Indian Academy of Sceinces.|
|Department/Centre:||Division of Biological Sciences > Centre for Ecological Sciences|
|Date Deposited:||11 Dec 2006|
|Last Modified:||19 Sep 2010 04:31|
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