My Atlas stayed chirping in January last year, he was approximately 6 months out of the water. It started out pretty random and awkward, I called it his "puberty" phase. My big female will occasionally let out a soft chirp but only when startled or when she wants a male to leave her alone. I've heard it maybe 3 or 4 times in the 4 years that i've had her. Atlas didn't get a dark throat until the following spring after he started calling, around 1 year out of the water.