I started a survival mode vault this week, and verrrrry carefully limited my population to 19 dwellers. Then I got a string of lunchboxes. Loathe to kill a dweller, and even more loathe to keep a Legendary dweller waiting at the door, I beefed up security on the 1st level and opened the vault for Jericho. I was expecting a swift and immediate Deathclaw response, but none came. That was two days ago. Since then I've let my population creep up to 30 and still no Deathclaws.

Am I tempting fate with a population above 20? Is it the fact I don't have a radio room?

I think Deathclaws come only after the 60 dwellers mark, or am I wrong ?

You should have attack from mercenaries by now.

Deathclaws come at 60 dwellers in normal vault mode.

Deathclaws come at 35 dwellers in survival mode, apparently.

I've got plenty of mercenaries attacking 5 at a time. For the time being, I'm trying to stay below the Deathclaw threshold. I hit the 33 dweller mark, then a kid was born, then a loser showed up at the door. Good for me, bad for him. I drug him straight to the killing room to unlock the Fitness room. That'll teach him to show up uninvited. Muhahaha!