Chicks chirping loudly then stopping

[JoshHayes]

Hi, I have two chicks that are two days old, and they were fine yesterday, chirping happily, but today one of the chicks was being rather loud and randomly stopping.

 

[MrFluffyandGirls]

Hi, I have two chicks that are two days old, and they were fine yesterday, chirping happily, but today one of the chicks was being rather loud and randomly stopping.

Are they warm enough?

 

[JacinLarkwell]

They might be too cold or one might have picked on the other a bit and hurt or scared it