The guys at texlaresearch.com have some great sounds on their website. The website states “These Recordings have been captured during our Bigfoot Research outings. If the recording is listed on this page we have some reservations about making a call as to what is doing the vocalizing. We are not claiming that all of these are Bigfoot vocals, just that they are currently unidentified and interesting. In most cases we are in very remote locations with restricted disclosure of our location, making human presence unlikely.
These were recorded in Central Texas on the Trinity River in the early morning hours of July 11th. There are 10 vocals in all covering just over a minute in duration, these did not occur at any other point either before or after during the night. No call blasting or active investigation was conducted on this night, one of our researchers entered the area placed the audio recorder at 20:30hrs and returned to recover the next day. Possible candidates for this could be Owl or Fox, however, neither seem a good fit based on missing elements such as the typical Owl “Whos” that would normally follow screams of this sort.”