<P> Another similar experiment was done in 1996--2002 by Hoover et al. on the relationship between the parasitic brown - headed cowbird and a host, the prothonotary warbler, Protonotaria citrea . In their experiment, researchers manipulated the cowbird egg removal and cowbird access to the predator proof nests of the warbler . They found that 56% of egg ejected nests were depredated upon in comparison to 6% of non-ejected nests when cowbirds were not prevented from getting to the hosts' nest . Of the nests that were rebuilt by hosts that had previously been predated upon, 85% of those were destroyed . The number of young produced by the hosts that ejected eggs dropped 60% compared to those that accepted the cowbird eggs . </P> <P> In this hypothesis, female cuckoos select a group of host species with similar nest sites and egg characteristics to her own . This population of potential hosts is monitored and a nest is chosen from within this group . </P> <P> Research of nest collections has illustrated a significant level of similarity between cuckoo eggs and typical eggs of the host species . A low percentage of parasitized nests were shown to contain cuckoo eggs not corresponding to the specific host egg morph . In these mismatched nests a high percent of the cuckoo eggs were shown to correlate to the egg morph of another host species with similar nesting sites . This has been pointed to as evidence for nest - site selection . </P> <P> A criticism of the hypothesis is that it provides no mechanism by which nests are chosen, or which cues might be used to recognize such a site . </P>

Brood parasitism behaviour seen between the two indian birds are