Zoo animals being preyed upon by wild animals

Back in May, a wild fox killed 25 American flamingos and one Northern pintail duck at the Smithsonian’s National Zoo. This made me wonder about other cases in which zoo animals are preyed upon by wild animals. Which zoo animals are most vulnerable to predation? Which types of exhibits are least secure at keeping these predators out?

One thing that comes to mind is open-topped small mammal exhibits. These exhibits are common for prairie dogs in the United States, and it seems like it would be very easy for a hawk to grab one of the animals and fly away with it.

Are there any other notable examples of this? What can zoos do / should zoos do to prevent these cases from occurring?

 

Another example the Edinburgh Zoo in Scotland, a Northern Rockhopper Penguin named Mrs. Wolowitz was killed by a fox on August 10. Mrs Wolowitz, oldest penguin at Edinburgh zoo, killed by fox

 

The last wood stork in Europe (in Vogelpark Niendorf) was killed by a fox.

There are fox-proof fences (Aalborg Zoo lost a lot of their Patagonian cavies to foxes), but I'm not sure what exactly they are/how they work. To my knowledge, zoos generally avoid electric fences unless it's to keep in dangerous animals, don't they?

With waterfowl like the pintail you mention, it seems like keeping them in open ponds is getting increasingly rarer as wing-clipping is becoming more and more controversial, so I think that problem will be more or less solved in a couple of decades when they all live in aviaries.

I'm not sure about small mammals like prairie dogs, though I do know many zoos let them in for the night so they're at least safe from owls. As for the daytime, aren't most birds of prey too skittish/sky around humans to even strike down in such a crowded area as a zoo? Here in Denmark, our most common birds of prey (sparrowhawks, kestrels, and buzzards) and owls (tawny owls and long-eared owls) don't take prey as large as a prairie dog.

 

Henry Vilas Zoo has lost several penguins to wild raccoons.

 

In a sense, I wonder if each of these incidents should actually be thought of as two breaches: One breach of the habitat/enclosure. And one breach of the zoo grounds themselves, which are supposed to have perimeter fencing.

 

Hoofstock are very vulnerable to predation, both being killed directly and being run into fences, startled, etc and dying. California zoos, especially safari parks, have lost a number of animals to cougars. Loose/stray dogs are another major culprit. They're rarely trying to kill (except the occasional bird), they just think it's fun to chase things. For smaller species, flamingos and penguins are more common victims because of the way their exhibits are built, and how many are kept together.

 

I’ve heard of zoos like Los Angeles avoiding open-air small monkey exhibits due to birds of prey being a danger to the animals.
I’ve also heard of raccoons preying on fish in open-air ponds or tanks.

 

The Alaska Zoo lost an Alpaca to a wild Brown Bear about 2 years ago.
@TinoPup mentioned Cougars killing hoofstock in California zoos, but P-22 killed one of LA’s koalas in 2016.
And while this isn’t a case of predation, Mr Stubbs the Alligator (who was most famous for receiving a prosthetic tail to help him swim) was stung on the tongue by a wild scorpion and drowned in his pool at the Phoenix Herpetological Society (just another reason for me to hate scorpions…).

 

Lots of examples of wild predation out there, with raccoons being the worst offenders in my experience, with owls a close second (though I do remember one dramatic cause of a zoo’s waterfowl collection being decimated by an otter in one night).

Even animals within completely enclosed exhibits aren’t always safe. I’ve had Cooper’s hawks perch on top of aviaries and grab birds from the outside.

 

No-one seems to mention rats. These were a problem for some aviaries in Chessington Zoo, and several birds were lost to them during the 1960s.

 

Indirectly, rats and other pest animals can be equally as deadly via spread of disease.

A two year old ch'mpanzee at Taronga Zoo named Kibale died in 1992 after contracting the Encephalomyocarditis virus (EMCV). EMCV is thought to be spread by rodents, where food and water is contaminated by infected urine and faeces. As in the case of Kibale, EMCV can result in sudden death as a result of acute myocarditus (inflammation of the heart).

Similarly, many animals in the region have succumbed to Toxoplasmosis, spread by feral cats.

 

This happened to an American Avocet Chick. It got pulled through the mesh and the staff was puzzled as to where it had gone the next morning.

Chronic Wasting (the deer kind) has been decimating populations in North America for years. Most namely half of the Nubian Ibex population being lost due to the disease. That’s one of the fears with Avian Influenza currently. Either a wild bird or person (through bird remnants on the shoe) will transmit the disease just by being near the animal.

 

I guess I'm a little surprised that the husbandry/ security/ exhibit/ accreditation standards aren't continuously updated or set higher any time one of these incidents happens. (Or maybe they are, but the predators just keep getting smarter and smarter).

I guess it may also be a case of sensationalized news making us think that such attacks are more common than they actually are (as a proportion of animals in zoos overall), and thus the accreditors don't feel an overhaul of the rules is actually warranted, even if the individual instances are memorable.

The idea might also be that these are natural behaviors (for the predators), and that while zoos need to take basic precautions to acknowledge this, they don't need to go to extraordinary lengths to stop every instance? Which seems a little odd given the conservation focus, but is perhaps a holdover assumption from earlier periods of zoo theory. For example, I've been reading the Amphibian Ark website where they basically want to assure full bio-security isolation for endangered amphibians, so it seems strange that we'd just have birds and other creatures getting killed over and over, and not demand a change in exhibit styles/security.

 

It's more like the opposite, predation is more common than it's made out to be. There's just only so much you can do about it, especially when it comes to species like foxes and raccoons that quickly dig, climb, etc right in.

 

I'm still shocked a single fox, in one night, could take out over twenty-five animals. I'm sure it's difficult for handlers to lose an individual animal to a predator but to lose two dozen in one day to a single predator... yikes!

 

Additionally San Francisco Zoo lost a couple kangaroos and wallabies to a mountain lion a couple years back.
Safari West and SDZSP are fighting a constant battle to keep mountain lions out of the hoofstock fields, as has been mentioned.

I also remember hearing of SDZ losing Crested Screamer chicks to a wild Great Blue Heron quite awhile ago.

In a particularly unusual case, Monterey Bay Aquarium had an octopus come in through their intake pipes and take up residence in one of the tanks; it got large enough to start eating the neighboring crabs and mystified staff for quite awhile until nighttime security discovered the culprit.
I believe it was Seattle Aquarium that had the same type of incident but with a much larger Giant Pacific Octopus that snuck in and started chowing on their dogfish sharks.

 

Fascinating. Thanks for this. As a guest I was always lead to believe the habitats were more secure. (But I'm a sucker for a false sense of security).

It seems like if we have the technology and expertise to keep foxes and raccoons and other predators inside enclosures elsewhere in the zoo, that we could just re-use (or reverse) that technology to keep them out of other enclosures that hold their prey. And that it would mostly be a lack of willpower or funding that would keep this from happening. Or perhaps a choice somewhere up the line that a particular exhibit design/style is more important to the zoo than protection from predators. (Or a balancing of those priorities, more likely).

But it's possible that I'm underestimating how often animals escape as well as how often they break in. After all, it's less likely that an escaped raccoon is going to make the evening news the way an escaped lion would!

 

This is used frequently, and is stated in every AZA care manual. The goal is to keep predators out as much as absolutely possible, but hungry wild animals can be a difficult adversary to thwart.

 

Animals really do have all the time in the world to try to figure out how to beat the barriers, whether it's to get in or get out.

 

I believe the Seattle aquarium mixed the octopus in the tank on purpose but stopped when the sharks were being eaten. There was a pretty well known clip of it eating one which was filmed for a documentary. This article says that the film maker wanted to film giant pacific octopuses brooding at the aquarium but when they heard about the octopus eating the sharks they filmed that instead but they did move the shark towards the octopus.

Eight arms not enough: Octopus had help snagging shark