Non veni pacem mittere, sed gladium.
That's a lady fox in heat.
If a women sounds like that in heat....what will she sound like when she wants you to take out the trash?
Solution: take the trash out before she asks.
It's called the "Vixen Scream". During the previous 2-3 years, that's all we heard at night; spring and summer. Very eerie. This year the fox seem to have completely disappeared for some reason. Our little cat survived the invasion though.