Kitten meowing a LOT

I realized this weekend that we have a momma cat and her (I believe) 3 kittens living in my neighborhood. I am trying to trap them to, at least, spay/neuter them. I caught 1 kitten yesterday and have been trying to let it settle in in its own room. I think it is about 5-6 weeks old. This kitten has been meowing A LOT thoughout this evening. I have gone in a few times today and put a little food near its safe zone. When I leave he has come out to eat. He also seems to have used the litter box. When I check on it the meowing stops. He does not want my attention. My best guess is it's trying to call for its mom. I don't know if I should put it out in a secure crate for the night near the trap in hopes of luring the others. How can I help it calm down?