This week a few but mostly 2 females are acting out with each other. They push their chests up to each other and kind of push each others necks with their beaks. I have 18 ducks and have not seen this behavior before, I have seen the males sometimes bicker and compete over a female mostly chasing but have never really seen the females do anything. Is this aggression or something else? The temperature has been single digits and they are penned up more with the shorter days. Could this be the issue? Any thoughts? Thanks in advance. Also it seems to be the Pekin female who has started this. Are Pekins typically more aggressive?