It's been a whole winter since I could get out and leave a recorder in my research area over night. Happily I did so Friday of last week and while it was deathly quiet on two of my three recorders, the third managed to capture some interesting audio. The first notable clip starts about a half hour after my friends and I dropped the recorder and walked away. In the clip below it sounds, to my ear anyway, as if something walks in through the forest to check out the area we've just vacated. This is what some folks in audio recording circles would call a "walk-up". While the clip is less than 4 minutes long, the visitor actually hangs around for close to half an hour, before subtly moving away. Take a listen to the foot steps as they approach. Do they sound bipedal, or quadrupedal to you?
http://sites.google.com/site/mongahela/myrecordings2011/WS500017-01-BipedalSteps-HP.mp3