I've since done a little research on this and now have a somewhat clearer understanding of brood parasites and I've learned that it's no simple matter. However, one thing is apparent and that's despite there being many quite logical theories about it there's no clear proof about why the parasites and those being parasitized act the way they do—see my comment to vagrantJin.
I've since done a little research on this and now have a somewhat clearer understanding of brood parasites and I've learned that it's no simple matter. However, one thing is apparent and that's despite there being many quite logical theories about it there's no clear proof about why the parasites and those being parasitized act the way they do—see my comment to vagrantJin.