Cows Spawn EVERYWHERE.

So, i was just playing on minecraft, flying on creative and A BUNCH OF COWS SPAWN IN MY FACE. and now there's roughly around 30 cows in my world.
Is this a bug or a glitch??? but, anyways, HELP.

I didnt spawn these cows... they spawned in front of my face while I was flying in creative. This is a creative, flat, singleplayer world.