Some female ducks and geese have evolved complex genitalia to thwart unwelcome mating attempts, according to a new study. Males of some species, such as mallard, have a notorious habit of "raping" females. They and other wildfowl are among the 3% of bird species whose males have phalluses big enough to insert into the vaginas of females, whether or not the female consents. Now, in the most detailed analysis yet of duck and goose vaginas, researchers have established that females of these species have evolved vaginal features to thwart unwelcome males. Tim Birkhead at the University of Sheffield in the...