Everybody's being mean to the duck!!!

[ccs123]

I have a male and a female mallard who are about 5 months old, as well as 4 guineas of about the same age and some 8 month old chickens. For the past two days some of the guineas and the rooster have been extremely aggressive toward the male mallard. They've been peacefully coexisting in a reee-range environment for the last two months. Please help!