If you hear an unearthly scream in the dead of night, hopefully it's just a fox. Most of the time, foxes don't make a lot of noise, but when they do, it can be scary. In the mating season both males and females can be very loud. The males call to announce their presence and to warn off competing males in the area, and a vixen screams to attract mates.

Music: 'Brittle Rittle' 'Double Drift'
Kevin MacLeod (incompetech.com)
Licensed under Creative Commons: By Attribution 4.0
http://creativecommons.org/licenses/by/4.0