I was cleaning the duck pen yesterday and had just filled the pool with clean, cool water - the ducks were very happy! So happy that "big momma" jumped in and started the mating ritual - head bobbing - funny quacking - flattening out, etc....my runner happily obliged her and climbed on top - the next thing I knew, my mallard drake flew in and jumped on top of him!!! My daughter was freaking out (so was I) so I went in the pen, thinking it would break it up - not the case...the mallard grabbed the runners neck, pulling out a hunk of feathers and pushed his head under water - keep in mind that the runner was on top of the pekin this whole time. I grabbed the mallard and literally pried his bill open and pulled him off and put him back outside...shutting the gate so he couldn't get back in. Why is he doing this? What can I do? Thanks!