what's in my yard

Alright i don't know what the hell it was but the other night it was about 3 am i went outside to roll up the wifes windows and i heard this scream come from down behind my house. Anyone who know's my house know's that i have a realy big back yard. And it realy sounded like a woman so much so that i almost called the cops it went on for about 10 minutes and i kept waiting to hear stop or help come out but it was just short burst screams. Like someone screaming at the top of there voice every 10 to 20 seconds. There's a dog around (though not sure were) that was also freaking out it would bark a few times and then you would hear this thing scream again. And i swear to god it was a woman though like i said it didn't make any works just shreaking blood curdling screams. Originaly i thought that it was a hawk but two things kind of threw me off from that the first was the fact that it sounded deaper a hawk almost sounds like a woman screaming but it's more shrill then what i heard. This had more girth more body more "size" to it then the typical bird and wasn't as high pitched. THe second thing is when it started to go away it didn't go fast and sounded more like it was coming from the ground then from the air. A hawk would have taken off and faded out much faster then this this sounded like a woman screaming as she was walking away. I heard nothing rustling though by the size of my yard and were this was and went i wouldn't hear anything like that it was farther away then that. It then moved up over the hill (again if you know my house over by brians about half way between there house and his parents) and away towards the river. I've realy heard nothing like this and was looking for some explination so much so i have been calling around about missing persons and anything that would have been reported on a scanner. There are lots of animals around this area though again it didn't sound like anything i have heard before and i've heard most if not all of them in the almost 20 years i have lived here. to be honest it's like nothing i have ever heard before. Any ideas????? And yes we have gone through the normal culprits and even joked about bigfoot. but hey you can state your case either way. Again it was close enough to a woman that i thought about running down there/ calling the cops though the time frame (3:00 to 3:30 on a monday morning) and the area (there's not alot of people roaming that area at any time we're talking about 15 or 20 a year and those are me and my kids and people i know) i realy don't know.....