What is "ululant"

Usage examples of "ululant".

For there was such a zest in him that- -Except here Radu's thoughts were arrested by an echoing, ululant, faint but concerted howling from the high plateaux and passes, as his grey brothers in the heights began to serenade a full and glorious moon where she tumbled through the darkening skies.

Worst of all, punctuating those ululant cries were bursts of words, too, spoken raspily, urgently: "