The Macaulay Library, Cornell Lab of Ornithology has made available all its digital recordings of the natural world dating back to 1929 available and accessible to all for free! What a fantastic endeavor! And the willingness to make it open access to all is truly wonderful! Thanks Cornell!
Here is a sample of one of the recordings from the sound library. As per the title it is a "dawn chorus in tropical Queensland, Australia". Absolutely delightful!
ML: ML 107159: Environmental Recording
More details here