Natural Born Killers

I found a snake in the wolf exhibit earlier this year.  That’s not entirely accurate – I actually found half a snake.  The week before that it was an opossum.  Earlier that month some visitors ran to me in a panic to let me know that the wolves were trotting around with a duck – still alive – in their mouths, taking turns handing the prize off to one another like an Olympic torch.  Our wolves may have spent all of their lives in zoos, but when they turned to look at me, their quacking prize held tightly in their jaws, their eyes said it all 

– Still got it.

I was proud of our pack... until I saw the news about the cheetahs over at the National Zoo.  It made our wolves look like rank amateurs. 

A major part of the zoo transformation of the last several decades has been environmental enrichment, or providing stimulus that improves the psychological well being of captive animals.  A key component of enrichment from the zoo perspective has been allowing animals to engage in behaviors that they would in the wild.  Otters, seals, and other aquatic animals are given water features to swim in.  Primates and parrots are given climbing structures.  Bears and apes are encouraged to forage for food.  Beavers are given logs and branches to gnaw on.  All good, wholesome, educational, and, above all, non-controversial, right?  Well, then there are the predators.

Predators kill things.  It’s what they do.  The entire body of a predator – be it a cheetah, a harpy eagle, a sand tiger shark, or an emperor scorpion – is a machine that enables it to capture and kill other animals.  Wouldn’t the natural extension of environmental enrichment be to allow predators to… well, predate?

In turns out, there are plenty of reasons not to offer zoo predators live prey.  For one thing, there is the increased risk of injury – potentially fatal injury – to the predators.  If I were a rabbit or rat suddenly thrust into an enclosure with a python, I don’t think that I would “go gentle into that good night”, I would fight and bite like my life depended on it.  Which it would.   As someone who has been bitten by several, I can attest that rats have a nasty bite, and more than one snake keeper has checked on their prized pet to find a feeder rat calmly gnawing on the severed head of the vanquished snake.  Now, when I put a rat in with a snake, I’m not intending for it to have a fair fight.  I’m intending for it to become a meal.  This isn’t Gladiator…

Unbeknown to many, the Ancient Romans were pioneers in the field of zoo feeding enrichment...

Of course, most often it’s the predator that does the killing, but not always cleanly.  At one zoo I worked at, I watched a clouded leopard spend an hour toying with a terrified bunny that had made a serious wrong turn somewhere.  The cat snatched the rabbit up, carried it for a while, dropped it, batted it around, and basically made the last forty-five minutes of its sad, lagomorph life a living hell.  Rabbits, if you’ve never had the pleasure, are screamers, which added to the gruesomeness experience.

That brings up one of the major reasons that we don’t usually feed live prey – public objections.  A lot of people would be upset by seeing a predator dispatching prey in front of their children, especially if it was done in an especially brutal manner (primates have an evil genius for torturing small animals they capture, pulling the wings off of birds or throwing the headless carcasses of rabbits at the viewing window – it really helps you remember how close to humans they are).  Of course, zookeepers and aquarists are all animal lovers, so it can also be hard for them to watch animals kill other animals.

Not surprisingly, public attitudes towards live prey vary according to the prey.  One study published in Zoo Biology reported that almost all visitors were fine with feeding live insects to lizards, fewer with the idea of live fish being fed to penguins, and fewer still with live rabbits being fed to cheetahs.  Interestingly enough, approval ratings were higher for feeding live prey off-exhibit than on public view.  Not surprising – I wonder how many Americans would still eat meat if they had to see the cow or pig enter the slaughterhouse.

Most zoos feed live invertebrate prey, others use live fish, especially for enrichment (if you’ve ever seen a fishing cat dive into a glass-fronted pool to snag a fish, it’s pretty awesome).  Rodents and rabbits are usually fed deceased, though live prey may be offered in some cases, such as a snake that isn’t showing interest in any other food.  Various zoos – balls, paper bags, cardboard boxes, papier-mâché “prey” – are used to simulate “killing prey.”  Predators may be fed with carcasses of rabbits, chickens, goats, or deer to allow them to rip up their “prey” naturally.  The feeding of live mammals – especially those other than rodents – just isn’t commonplace at many zoos.  In some countries, it’s actually outlawed.

Some visitors that I talk to think that I feed the big cats by throwing in a live goat once a week, while others seem to think that I have persuaded them somehow to become vegans (the cats, not the goats… the goats are already vegans).  While the truth is much closer to the first theory than the second, most of the large carnivores in zoos will never hunt and kill live prey… at least, not prey provided by the keepers.  That makes it all the more exciting for them when that hapless squirrel or rabbit or duck finds its way into the enclosure… and doesn’t always find the way out.