Boys will make noise almost everynight if their happy. I dont think theres a specific season because mine did it all fall, winter, and now spring. Yes females are rounder than males. If you have boys they will be kind of agressive in grabbing onto other ones in the water, girls will never grab onto one. If youve never seen any of them grab onto another one I doubt you have males because it doesnt take much to please them and make them want to mate. You will want an almost all water set up with filter, some say you will only get eggs if the water is running, but I dont know how true this is. Give them a few monthes, after only a week I doubt you will hear any noices, their still settling in. Girls will make noise sometimes, so when you picked it up, it could have been a girl or boy, girls just dont CALL like males do. I would trash the moss and make it an aquatic set up, no water bowl. They spoil the water FAST and they enjoy the aquatic set up A LOT more, and they try to mate more. When I had them in your kind of set up, I only heard calling every now and then, but in the new vivarium set up they call every night.