Apologies if this is silly, but I've been super curious. My rooster puts on a dance for the ladies, and lately he's been dancing for some of my straight runs, ranging from 1 month to 6 months old - he picks specific birds in my flock of young ones and dances for them? Can roosters instinctually...
Imagine: a neighbor's cat gets into your yard, and kills one of your birds, what do you do? You may warn the neighbor to keep the cat contained. You may set out a trap, or have other means to keep the cat away. But, do you call the cat aggressive? More then likely not.
If a fox, coyote, hawk...