Activity in the Ravine tonight

I had activity in the ravine tonight. And this time I wasn't alone in witnessing it. My girlfriend Tracey wanted to see the deck that over looks the ravine, so we walked down to to the deck. Ahead of us in the ravine we heard movement. Whatever was moving was big and moving on two feet. Tracey's two daughters were also with us. We listened to it move and Tracey saw some branches move ahead of us. I couldn't tell how far away. Probably 100 feet or so. We whistled several times and we got a response- from another part of the ravine. There were apparently two of them. Whatever was responding to us was hooting at us in a deep voice. Tracey said she had never heard anything like it before. I unfortunately did not have my digital camera or voice recorder. I was caught completely unaware. This whole incident lasted about 20 minutes. We plan on going down to the deck Wednesday night, to see if we can repeat what happened tonight. This time I will have my equipment near by.