The Democrats didn't choose their own mascot. It was assigned to them by a Republican, newspaper, comic artist, in the 19th century. I think it was in the 1870s.
I think a long time ago the Democrat symbol (to help illiterate voters cast their ballots) was a rooster, before the cartoon jackass caught on.
all the more reason for them to make a change. i think the artist was being too kind. *natch, natch, wink*. when i look at my donks, i don't see cowardly creatures. quite the opposite. i'm leaning toward pollyannaish's suggestion. but those are hard to find. lol
(The immortal) Thomas Nast.
Thomas Nast - same guy who broke Boss Tweed and Tamany Hall.