Brown headed cowbirds lay their eggs in other birds’ nests, abehavior called nest parasitism. When this strategy succeeds, thehost birds accept the cowbird egg as one of their own and rear thecowbird chick. When it fails, the host birds reject the cowbird eggas an imposter and remove it from the nest. Why do any host speciesaccept cowbird eggs in their nests? This seems maladaptive sincethey are expending energy that should go toward raising their ownoffspring on cowbird chicks. Biologists have proposed twohypotheses: first that the parasitized species have not yet evolvedthe behavioral response of egg ejection yet, but eventually will.The second hypothesis is that the host birds are physicallyconstrained since their beaks are too small to remove the largecowbird eggs from their nests.
Propose an experiment to determine which of these two hypothesesis correct.
