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Zoo animals thriving after an escape?
Not gonna Raichu a love song
_sexorcist_ wrote in little_details
In my novel, a respiratory disease greatly reduces the human race. Only the humans- it doesn't affect animals because it was artificially engineered that way. Yes, I promise this has something to do with a zoo. XD

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!

I can't help with the logic of the thing, but I think it couldn't possibly hurt to give calling the zoo a shot. The people who do outreach stuff or who run the docent program might be helpful, if not for their knowledge, because they might know who at the zoo WOULD know what you need to know (if you can get names, that's sooo helpful). They are also usually super-nice people.

I was in a zoo docent training program and the zookeepers and heads of the various critter departments LOVE to talk. They can be busy, but it's absolutely worth a shot.

Definitely offer to make a donation, maybe to some part of their educational services.

Good luck!

You might want to take a look at the novel Emergence by David Palmer which includes almost exactly this scenario

Basically lions, tigers etc. would flourish - they would have ample prey and no competition worth mentioning, and they stay in groups so would easily find mates, animals like snakes which tend to be solitary would probably not do so well, they would rarely find mates (and many of the zoo species will die in the first winter in a temperate climate).

Hope this helps.

Basically lions, tigers etc. would flourish

And bears? Oh my.

Peacocks. They wander around the Bronx Zoo, even when there's snow on the ground, and they thrive.

These guys aren't exactly zoo animals, but they're an exotic species you wouldn't expect -

There's so many other factors that would affect this that you could make a plausible argument for a lot of different animals that might survive, but not all of them, and it depends on how long after this escape you're talking about. It's hit or miss if tigers would make a steady population, for ex-- how far would they roam? Would they ever find each other again? That's up to chance, so yes or no. If you're in an area where they can get food, they'll probably survive if they don't get hunted down. I'd put more money on lions since they stick together and zoos are likely to have more of them than tigers (since lions are cheap and easy to breed, and social).

Why wouldn't the zoo keeper let pythons go, but they'd let the tigers go? Is it some sort of charismatic megafauna bias speaking? Releasing the reptiles would be easier if they're in a hurry since they're generally all kept in one building, versus having to wander over acres and acres to let out the big mammals. That's probably beside the point of your story, but you mentioned it so I thought I'd ask.

Smaller animals are more likely to thrive, just given my own experience-- I live in South Florida and we have a lot more than pythons. We also have zoo escapees: macaws that escape Parrot Jungle during Hurricane Andrew or after Parrot Jungle moved, since they were free-flying. We also have huge flocks of feral mitred parakeets hanging around my apartment building and school. We've also got tengu, iguanas, and other reptiles, but those're more private releases.

Pretty sure you could call a zoo, someone would probably be really excited to discuss it!

London has feral parrot flocks now - they seem to do reasonably well despite the occasional cold weather, not sure how well they'd do in a REALLY cold winter though.

"Hi! I'm a writer working on a novel, and I'd like to consult you as an expert in your field. Mind if I ask you a few odd questions?" is just about the most flattering thing you can say to a stranger. I've talked to off-duty cops, firefighters, linquists, physicists, etc. No one has ever turned me down.

If you find the right people, you'll probably get a ton of help from zoo folks. There's a zoo program affiliated with my department - you don't happen to be Cleveland local, do you? I'd be happy to introduce you to some of the zoo affiliated grad students...

Close, but no! I'm nearer to Indianapolis, and their zoo has a lot of educational programs, so hopefully I'll get some luck there!

There's a show called "Life After People" which covers the state of various cities, environments, and animals species after humanity suddenly and inexplicably disappears. Find some episodes which correspond to the environment of your book and that should give you plenty of ideas. :)

I've watching the two hour season opener of that and taken notes, but I need to go through and check specific episodes that might be helpful. Thanks for reminding me!

Wallabies seem to thrive in the UK if we don't get too many bad winters in a row (and even then there was debate for a while as to whether the Derbyshire colonies had really died out). The south of England has parakeets and the like too.

There is a colony of wallabies on an island in Loch Lomond up in Scotland. Peacock escapees are fairly common, feral peafowl populations are generally a nice safe news story in spring if it is a slow news day (because that is when they get loud with mating calls), the theory behind the mysterious big cats in the UK is that a lot were dumped into the wild in the 1970s after a law change and have bred. Wild boar have done alright after they escaped in the UK, as have various deer. I'm just going off UK examples because that is where I live, but AFAIK there is no reason why animals wouldn't prosper in other countries too if they suddenly escaped into the wild and no one went and rounded them up. Obviously there are a lot of factors, and luck would be a big one, but I see it as plausible. Try googling for feral animal populations, I think it would give some examples you could extrapolate from.

Wikipedia link to feral animal populations:

I second everyone who has said you can approach a zoo near you and ask various questions. I'm someone who visits zoos around the world, and my experience has been that generally the zookeepers (not the bored summer interns, the people trained and interested in animals) have been really friendly and excited to talk about their work/animals.

Others have mentioned peacocks, which I also agree with. They wander zoos freely and I have a friend who has raised some up in Maine, so they're not too high maintenance. They'd need peahens to mate with if they're going to survive as a breeding population, of course.

I don't know if your zookeeper is going to release smaller animals, but anything in the rodent or small bird family is going to be preyed upon not only by other, bigger zoo animals, but regular predators already in an area such as owls, hawks, and foxes.

In the area where I live (NJ) there aren't too many indigenous large animals that would pose a threat to bigger zoo animals, other than maybe bears (though I think big cats and bears would be smart enough to just stay away from each other, generally). Other parts of the US do have larger predators like mountain lions or wolves, though.

If the city's in chaos, and people are dying and panicking and civil order is going out the window, think of which animals are going to get shot on sight, either by panicking civilians or the remaining law enforcement population. Because tigers being loose in a city won't help anything, plague-related or no. Also, thinking post-apocalyptically, which animals are going to be competition for resources against the human population?

Edited at 2012-03-14 05:22 pm (UTC)

Very minor sidebar on the felines. I think I remember reading, that tigers in the wild are capable of group behaviour (perhaps not as much so as lions, still...), it's just there's strong pressure against it in the modern world. Also, in Africa anyway, leopards can live in high populations in even urban areas, so they might in the end be more important to these people than tigers.

I don't know if this would apply to animals raised in heated zoos, but some tropical animals can survive cold far better than you'd expect.

For survivors, though, my money would be on the birds, especailly the smart crows and parrots.

Good luck with the book!

I don't know, but it reminded me of the story about that guy that owned all those big cats and let them go before he committed suicide. Story here (

Yeah, I followed that story as it was happening, and as I do my research it keeps popping up. At least now I know what to do right before writing angry scenes- go look up that story, because just reading about it I get furious and sad all at the same time.

My bet for survival as long as they can get out the gates are the large hooved mammals. Zebras in particular are very hearty, fast, and adaptable. In my area it is not uncommon to see them out all winter in the snow at the zoo. Cammels are also very hearty and able to defend themselves well, and would stay in a group to reproduce.

African wild dogs reproduce quickly and are extremely intelligent pack hunters that would likely do well. Keep in mind that if there are lots of dead bodies many of these animals will not mind having a human snack until they figure out what else to hunt- even lions will scavenge if there is nothing else around.

Animals that rely on camouflage in thick vegetation will be more likely to have a hard time than animals that rely on speed or strength.

Sounds like a fun project! I hope to read it someday.

I'm not sure about long term, but an awful lot of tropical species do fine in the cold. There was snow on the ground during my last visit to our zoo, and the gorillas, zebras, elephants, ostriches, otters, red pandas, tigers, lions, camels, monkeys and warthogs were all outside. A lot of other animals were too, but they're ones you'd expect (snow leopards, wolves, ducks, owls, eagles, reindeer, caribou, buffalo, otters, moose, beavers, and other species native to our area) It was a pretty warm day (about 10-15 degrees Celsius), but we had four or five inches of snow on the ground.

That having been said, our zoo just opened a display with penguins, and they would be so screwed if they were released just by opening the doors.

Also, I think it was at the end of the Life of Pi where the narrator asserted that large predators have been known to hide in cities for years without anyone noticing. I don't know accurate that is, and I hated that book, but yeah. Evidence?

And finally, my city has a really, really healthy population of bunnies and deer, so your big predators won't starve if they can hunt. And they'd probably end up eating a lot of the dogs and cats whose owners had died, and competing against feral dog packs and cats. And if they reach the outlying areas, there will be horses, buffalo, cows, llamas, alpacas, goats, and "other" (all or which are kept outside during the winter around my city, and most of which might be set loose if their owners and everyone was dying). I think escaped grazing animals would do better, though, grass being easier to find than meat and all. It's not like your characters couldn't be attacked by wild buffalo or moose.

Well, there's the light rail coyote, also made sort of locally famous in a song by Sleater-Kinney. :D

I live very close-in to downtown, much closer than the airport. And our lots are pretty small, no big acreages unless you count the city park. A neighbor claims that a roaming coyote caught one of her cats not long ago. Make of that what you will...

Odd as it may sound? Large birds. Several (more than ten) years ago, someone decided that northeastern Oklahoma would be a great place for emu ranching. It wasn't, of course, because there's no consumer market for emu in northeastern Oklahoma. When the ranchers gave up, a lot just released the birds. It's hilly country with forested areas, tallgrass prairie, and cattle/horse ranches about evenly mixed, with lots of lakes and creeks, and there weren't a lot of natural predators for them. For a few years after the last of the ranches shut down, you were about as likely to hit an emu with your car as you were to hit a deer.

(ETA: Also, I have a story about a friend getting attacked by an ostrich at the zoo when he was dumb enough to stick his hand through a fence, so if you're wanting an absurd animal to reference, an emu or ostrich might be a good idea.)

Edited at 2012-03-14 11:58 pm (UTC)

Echoing the large birds comment - emus and cassowaries, given a few breeding pairs, could populate quite quickly, and any predators would have a hard time taking them down.

You might also want to look at - I wouldn't be familiar enough with wherever your setting is to point you a particular way, but I'd suggest any animal with a variable diet could keep going, but your very particular eaters (pandas, as suggested above) would cark it.

To the comment that predators like tigers would "forget" how to hunt while in the zoo, or even captive-bred--not true! The tiger cages at the Miami Metrozoo are marked with little stencils keeping track of the kills that the tigers have made over the years--raccoons, possums, birds, and all kinds of things that have wandered into their enclosure and became an instant snack.

Competition between the larger predators might make the biggest difference to their survival, but not necessarily lack of prey. Deer are waaaaay overpopulated in most areas in the midwest, and it's lack of habitat that limits most of the other natives. Prey would be abundant at first, but would eventually even out (with deer probably over-foraging like mad for a year or two, then declining as environmental limitations, including disease, took their toll).

I think to have a stable population of large predators over time, there's a minimum number needed. We have cougars around us in northern Illinois, for example, but the DNR doesn't acknowledge it publicly because there's not a "population" of them--probably fewer than twenty, at a guess. Ditto on wolves--they pass through every once in a while, but not in any real numbers.

Animals kept in zoos in larger numbers--people have mentioned camels, for example--would have an easier time retaining a presence than something like a snow leopard, which most zoos might have only one or two of. Zebras probably wouldn't survive. They are fed year-round in zoos, and would not have the skills to find vegetation through the winter. Deer, rabbits, and cows all digest their food twice (rabbits eat their own pellets, mmmm) and gain more nutrients from less food. But zebras need to eat pretty much constantly to survive. Of course, they migrate hundreds of miles every year, so if they made their way south they might be okay.

Tigers, after eighteen years, wouldn't have much of a presence--if there are only a few to begin with, I'd think surviving humans would have killed them off as they came across them. Maybe hyenas, Cape Hunting Dogs, and the like would still be around and would be very scary.

To the comment that predators like tigers would "forget" how to hunt while in the zoo, or even captive-bred--not true!

Very much seconding this. I volunteered at a zoo for a while (sorry, OP, not long enough to be able to offer an answer), and our lioness was notorious for catching everything she could. She had to be spayed when our lions were taken off the breeding program, and she didn't bounce back from it too quickly. She refused food for several days*, and the keepers were really starting to worry unti the day a duck blundered into the enclosure. She was more than happy to make short work of it, and after that she immediately started eating normally again.

*Yes, lions in the wild tend to gorge and then not eat for a week, but ours were on a 'smaller portions more often' diet to keep them more active and appealing to the public.

How many of each animal is in the zoo? You might look up the average age of survival for your large predators, because if there are only two or three in a zoo, they might not sustain a viable population... but they might still be around in 18 years, older and slower but still deadly. I'm not sure how long they live. Also, investigate the natural range of large predators - they roam a fair distance to get their food, because their food moves around a lot. Hooved animals like zebras, antelope, etc can travel 20+ miles a day in search of forage.

I disagree with the zebra comment above. Zebras are foragers just like horses, and naturally live in a dry but temperate climate. They are likely to survive in any ecosystem where horses will naturally survive. I live in the mid-Atlantic region, and can think of three farms within an hour of me that have zebras out on open pasture year-round. If you let them go in the midwest, they'd breed just like the feral horses... and they'd interbreed with the horses, although I don't think the offspring are fertile (look up the zorse). They might prefer a more southerly range, but that's about all the difference. Equids (zebras, horses, etc) are rather adaptable, and can go very far with very little food, so it's likely that the zebras (and other hooved things) will establish themselves in the suburbs of the city, where there will be unkempt lawns, roadsides, golf courses, parks, ball fields and the like to munch on.

Look into the animals surviving in the exclusion zone around Chernobyl. The place is pretty much a living laboratory for a humans-depleted scenario, and fits somewhat with your timeframe. There are wild horses, bears, all manner of birds, maybe wolves, too. These are mostly animals that have migrated in, although the horses were released on purpose, I believe.

Think about the niches the zoo animals fill in their native habitats. They will be competing with the local fauna that fills those same niches - gazelles vs. deer, mid-sized predators (hyenas, mid-sized cats, foxes, etc) vs. foxes, wild dogs and coyotes (of which there are many in urban areas these days), etc. The most generalist species will be the most likely to survive, which means foragers and scavengers like, again, hooved mammals, raccoon- and possum-like animals, smaller to mid-sized predators. The big question is, are there enough of these in the zoo to sustain viable populations? Two by two, ark-like, is not often sufficient, especially for larger animals, but a base population of three or four, though inbred, might be viable.

There are definitely wolves in the exclusion zone around Chernobyl. One of the PBS shows did an episode about the wolf population in the area. (Video in the link is US only.)

Last summer, a mountain lion was hit and killed here in Connecticut - they believe it was wild, not a release. We've also had rather urban bobcats living locally (not downtown, but near the shopping centers and Walmart) for years. Cats seem to be pretty adaptable. And on a trip to Chicago, I was rather surprised to see a good sized herd of deer hanging out in a cemetery - by all appearances happy and healthy...

This comment will not be at all helpful. I just had to say that reading the responses here keeps conjuring up that image from "Peewee's Big Adventure" of Peewee running out of the burning pet store with snakes in his hands, screaming in fear. :D I guess I'm picturing your zookeeper doing the same thing.

In the immortal words of John Rogers of Leverage: "Writers, if you need an expert opinion, just call someone and ask. People say that they hate their jobs, but almost everyone loves to tell people about what they do."

The only other thing I would mention only because you are talking about decades later, but you may need to think about how many pairs you are starting with of each animal. A lot of Zoo's have maybe one pair of rarer breeds making finding viable mates a problem outside of their original regions. Which doesn't mean that 18 years on there may not still be the odd one or two prowling around.

Tigers, I went and looked it up. There are approx six thousand tigers in captivity (private individuals) in the US, of which four thousand are in Texas. If the private owners release their cats then it will make zoo releases look like small fry. It is certainly enough to establish viable populations, what with the distances tigers will travel.

Ohio is another state that's given carte blanche to exotic pet owners--although that's in the process of changing, thanks to outcry over the Zanesville incident (linked above by shananagems.)

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Remember to take into account the fact that captive animals often don't have comparable survival skills with their wild counterparts. So your tigers that have eaten dead meat their whole lives are going to have a hell of a time hunting. If you have a particular species you want to survive, maybe consider having that species have been part of a reintroduction program or studies for developments of reintroduction programs (though these don't exist for all species), because they might get more survival skills from those.

Also, domestic animals gone feral produce a pretty strong competition for resources. Feral dogs exist even in non-"decaying" cities, and cities that are partially abandoned often have strong feral dog and cat populations. Some wolves can interbreed with domestic dogs too, so the might integrate with dog packs rather than remain isolated.