There was an ethnicity poll just like this on Beast Forum, and the results on that Beast Forum poll were generally the same as the results of this poll. In other words, on the Beast Forum poll (which had hundreds of votes), about 80% to 90% of people were white.
One thing that both this poll and the Beast Forum poll have in common was a very low number of Asians.
So the question is, why are most zoos white? (I.e. about 80% white). Or, could it be that most zoos who go to online zoo forums are white, while the worldwide number of zoos (including those who don't go online) might be more diverse? Might there be large non-white, non-English-speaking portions of the worldwide population that are zoo but never go to zoo forums? Or maybe the worldwide zoo population really is 80% white.
One possibility: several major English-speaking countries like the U.S. and Australia are mostly white, so maybe that's why people on zoo forums are also mostly white. There is very little activity in the Mexico personals section of Zooville, so it seems there aren't many zoos from Mexico on Zooville.