Knocking in Placer County, California

Me and my fishing buddy went camping at French Meadows reservoir to get in the last days of the season. In the campground we were alone and everything was shut down, nighttime temps were 32 and 29 the second night. We were in the last campground on a dirt road a mile east of the lake. Very few hunters were in the area because it’s a game refuge and no other fishermen were in the area. We got in camp around 9pm because the fishing was great and it took time to clean our fish. As soon as we got there i gave out my whoop whoop whoop whoop, hoping to hear a return call. This went on every hour and my buddy all the while half cracking up looking at me like I’m nuts. At 1am my buddy was asleep in the sack [his Cherokee]. At 1:30am, I let out my last calls, you could here the echoes for 3 to 4 second's afterward. 10 second's after my call I got a woooraa back. I was shocked to get my first return call ever, it sounded to be a good 300 to 500 yards out and with a two D-cell flashlight, Ii was not going to investigate. The direction the sound came from there were no roads or camps. I knocked on my buddy’s car and got him up hoping he had heard it but all he said he heard was me. From now on I will take a recorder. I’ve been hunting fishing and hiking all my life and that was the only time I heard this sound. It was not a coyote, a cat or an owl [I know them well]. In my heart I believe it was either a person or a bigfoot. The remote area from which the sound came from tends to make me believe the latter.