Male doesn't bellow (call) anymore

I am not sure what that would be caused by, maybe stressed? Tank too cold?? I'm not sure, I hope someone here can help you, google certainly didn't help me find the answer.

Doing some more reading...maybe it stopped calling because there are no other males to respond to the calling? Therefore your frog doesn't feel the need to call and defend his territory? Just taking some guesses here off some of the literature I was reading (specifically WHY they call in the first place other than for breeding purposes)

Wow,
Thanks for doing that research. That is very nice of you. One thing I thought of myself is maybe it is because I have not put him through aestivation. On the other hand he used to bellow quite frequently. Probably even more so in the spring and summer.

How's the humidity?

Though sometimes I get his coconut fiber too wet it is most of the time probably too dry. I've been meaning to put my Western Caliber III thermometer/hygrometer in the cage. It is extremely accurate.

I read some bizarre information last night. There is a pesticide called 'Atrazine'. It is currently being used heavily in the midwestern US on crops. Scientists are finding that it can turn male frogs into females. The small percentage of male frogs that don't turn into females become less viable.

You should do that, if the humidity is too low, he will think it isn't breeding season and has no need to call.

Not sure if you are blaming Atrazine, but don't. Humidity and temperature are usually the reasons to start/stop an African Bullfrog calling. Also bear in mind that while it's a deep sound, it doesn't travel very far, so it's also possible you're missing calls.

Thanks John,

I have read your recommended temperature settings as 77-90 degrees F in the vivarium but what do you recommend as the optimal humidity level?

Also what do you find that works best for maintaing optimal humidity?

I am curious as well what optimal humidity for croaking is. I have a baby Adspersus and he croaked a couple of times a month or so ago and hasn't in a while.

Well, I keep my bullfrog terrarium on the dry side, but he spends a lot of time in his pool. That's where he always calls. He also responds to thunderstorms by calling.