Why is my cat (and others) laying on my new onions in my garden?!?

[mel.]

I planted yellow onions last month; they were doing just fine. However, I started to notice that the "tails" of my onions were laying down after a couple weeks. I've discovered my cat (and 2 in the neighborhood) like to lay in my onion "patch"...which is an empty space in between some perennials. They seem to like to roll on them- WHY is this? They're killing my onions, I think! (Will my onions grow without the "tails"- because then they cannot bloom?) ^^----~~