22 mayo 2015
Mexican Jays (Aphelocoma wollweberi) distinguish between heavier and lighter peanuts without opening the nuts. The birds do it by shaking the nuts in their beaks, which allows them to ‘feel’ nut heaviness and to listen to sounds produced by peanuts during handling.
http://feeds.sciencedaily.com/~r/sciencedaily/~3/iJ7VGnZDSIE/150522174719.htm
