On Cooper Road in Milton there is a sizeable flock (~80) of Brown-headed 
Cowbirds.  I am sure that they are taking advantage of the near by farmyard 
so there presence does not surprise me.  However, there level of singing 
makes me wonder: because of their parasitic ways do Brown-headed Cowbirds 
begin to sing and initiate courtship in response to singing and courtship from 
potential hosts (i.e.- Northern Cardinal)?

Roger Masse