Our son Brian sent a link that included this interesting fact from Wikipedia:
Chewbacca’s dialogue was created from recordings of walruses, camels, bears, and badgers from Burtt’s personal sound library. One of the most prominent elements was an American black bear living in the Happy Hollow Zoo in San Jose, California. These sounds were mixed in different ratios to create different roars.
We often visited Happy Hollow when our children we young, and we now take our grandchildren there. We’ll view the black bear there with even more respect in the future.