Originally posted by sjusovare
I would advise not to, apple cider is fermented and contains alcohol and potentially yeast.
Not all cider is fermented. @Glidingcameron probably refers to fresh apple cider as purchased in the grocery store -- it's basically unfiltered apple juice so perfectly acceptable as a substitute for apple juice.
However, that is NOT to be confused with what @sjusovare is referring to, hard ciders like Angry Orchard. Those should NOT be fed to your gliders.