The Acoustic Atlas curated by Montana State University Library has "more than 2500 recordings of species and environments from throughout the Western United States."
I found that within this collection are 138 public domain recordings and another 957 with a Creative Commons use license. They are fun to explore and listen, and perhaps you will find a use for them in your shows. Some are brief, but some recordings stretch for several minutes.
For example, follow this link to hear a one minute flyby of Canada geese.
Here's 36 seconds of a wood stove.
And here's nearly three and half minutes of September sounds at Yellowstone Lake.
To search by license for the recordings I mention above, go to this advanced search link, then set "license type" to either "public domain" or "creative commons".