Zoo animals thriving after an escape?
In the later stages of the disease wiping out everyone, when the city is in chaos, one of the dying zoo workers at a rather large zoo decides he can't leave these animals to starve without caretakers. So, he goes in and opens every last cage, leaving double doors and exhibits wide open, and by the time anyone realizes what's happened it's far too late to contain the animals. There's no infrastructure left anyway to call the shots.
It's a temperate zone, and the remaining humans over time manage to band together and create a quarantined city. My novel takes place approximately 18 years after the collapse of society- and therein lies my question.
In a temperate zone, with few humans threatening their existence, which zoo animals might thrive? Which would die off immediately? Would the native deer and other woodland creatures get wiped out by the exotic predators, or would two or three tigers or lions even last long enough to start building a steady population? How would wolf packs extending in from the Yellowstone areas and retaking their former lands affect the apex predators that have now been unleashed? Would there be meerkat stealing my character's fish off his drying rack?
This isn't even the main plot of the story, but I'm having so much fun with the idea! "By the way, buddy, don't go hunting alone. Rogue tiger will eat you." "...A rogue WHAT?"
I've tried Google and such, but unfortunately, pretty much all the escapes I can find were able to be quickly controlled- they either caught or killed the animals fairly quickly. The closest thing I can find is exotic pets escaping, such as pythons in Florida, but pythons wouldn't be a good example of a zoo animal that would easily escape- the worker wouldn't go through and open all the tiny aquarium style exhibits, too.
I've thought about emailing the zoo nearest to me and possibly making a donation and asking for a bit of a zookeeper's time to discuss this with an expert- do you think that's plausible, or would they laugh me out of the place, since I'm not exactly Stephen King or anything? XD
Thank you for any help or advice you can provide!