I also noted on the yahoo page that you could click on ten monogamous animals and loved it! The gibbons photo was so tender it just got to me, and it was so cool to learn that the American Bald Eagle is monogamous as well! Too cool. I did not know that swans were monogamous but do know that Canadian geese are (but were not mentioned in the given ten).
I suspect that Cardinals (the bird) are monogamous. There is a single pair here in my yard year round and they’re never far apart.