Apply! I once decided that my local zoo would never take me and applied to every zoo job that existed, including curators! I have 9 months of volunteering weekends at my local zoo, that is all and I got offered 5 interviews, in the end I decided I couldn't move, so turned them down and am just waiting patiently for my local zoo to spot my potential!
But basically, you should go for it, apply for all 3 and show them how passionate you are about zoos, you have a good chance.