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Native Californian, biologist, wildlife conservation consultant, retired Smithsonian scientist, father of two daughters, grandfather of 4 small primates. INTJ. Believes nature is infinitely more interesting than shopping malls. Born 100 years too late.

Friday, December 28, 2007

On escaping zoo tigers

I would like to weigh in with a few remarks about the recent tragedy at the San Francisco Zoo where on Christmas Eve a Siberian tiger escaped, killing a young man and wounding two others.

So far there are no witnesses to the escape, but Police Chief Heather Fong did not exclude the possibility of intentional or inadvertent human activities and called for a criminal investigation.

Such a notion is reinforced when a television zoo celebrity like Jack Hanna states that the tiger's leap from the moated enclosure would be "virtually impossible". Apparently he was under the impression that the moat was in compliance with AZA standards.

If working with wildlife teaches you anything, it teaches you not to underestimate the abilities of animals.

The depth of the tiger moat at the outer wall is now said to be 12.5 feet, which is less than 16 feet with a two-foot overhang -- the height recommended by the Association of Zoos and Aquariums (AZA). The width of the moat, as shown in a diagram in the SF Chronicle on Dec 27 -- is 15 to 25 feet, but SF Zoo Director Mollinedo reports that it is 33 ft.

This brings me to 2 observations which are common knowledge among zoo biologists.

First, the leaping or escape abilities of tigers or any other species obey the principle of the bell-shaped curve. A barrier may stop most animals--the ones with average abilities, but an exceptionally athletic or clever animal may be able to breach it.

Second, when an animal is strongly motivated to escape, it may perform feats perceived as "virtually impossible". Years or lifetimes may pass before rare circumstances compel a previously complacent animal to attempt escape. Designing an escape proof enclosure must take these realities into account.

Dave Rentz, a childhood habitue of the SF zoo recently posted a good example of the motivational factor at work. In 1959, Carey Baldwin, then the zoo's director tempted the resident tiger with a chunk of meat at the end of a pole. It motivated the cat to take the tremendous leap, which it accomplished on the first attempt. Fortunately, it ricocheted back into the enclosure. That was enough to decide the director to curtail the tiger's access to the outdoor enclosure.

That was nearly 50 years ago, and since then the zoo and the tiger exhibit have changed a lot.

It is possible that Tatiana simply decided to make her break at the time the three young men were outside the enclosure, and then the cat went into predation mode.

It is also possible that one or more of the young men crossed over the public guard rail and taunted the cat, thus giving it motive to breach the barrier and "pursue the prey". I have a feeling that the survivors of the attack may know some things that haven't yet come to light.

Zoo workers must protect the public from the animals and the animals from the public. In reality they are called upon to check the escape tendencies of their charges far less often than they are called to protect people from the consequences of their own ignorance or stupidity.

In any event, the zoo is ultimately held accountable when an animal escapes. More often than not, animal escape policies kick into practice and disaster if not embarrassment is averted. But now and then an animal escape takes a tragic turn, as did this one, and the zoo director's worse nightmare comes true. It remains to be seen whether the AZA accreditation team that routinely reviews the practices and conditions of member zoos, actually failed to note this deficiency and/or enforce its recommendation.

All of this reminds me of a similar tragedy that Dr Theodore Reed, former Director of the National Zoo in Washington DC related to me before his retirement. Nearly 50 years ago, a small child in the care of an inattentive grandparent squeezed through the public barrier and walked up to the lion cage. The cat reached through the bars and killed the child instantly. It took this tragedy for the US Congress to finally respond to the zoo's standing request to fund major renovation and safety upgrades.


Anonymous said...

That's an excellent commentary on this whole sorry affair.

I hope that laws on keeping tigers as pets in certain states are given their long overdue tightening in 2008. All too often, it turns out tragically for both the cat and the people around it.

Camera Trap Codger said...

Thanks, and I couldn't agree with you more about tigers, or exotic cats in general as pets.

Owlman said...

Chris I agree with you and think that this Tiger was motivated to exceed it's "normal"
capabilities in this instance. The barrier is apparently not high enough and that should change. I encourage you to write a letter to the Chronicle with your commentary.

Camera Trap Codger said...

Sunday's SF Chronicle had another piece on the event, and some interesting though emotional responses. Dave Rentz's and Carey Baldwin's experience with the moat'-leaping tiger in 1959 was also cited. Reno Taini also sent Chronicle information on the leaping abilities of tigers based on the filming of Chang, by the producers of King Kong -- interesting stuff.

Steve Bodio said...

If you have worked in zoos ( I did almost 40 years ago) the public's determination to abuse animals and/ or try to get killed is a given, but for others it is amazing.

How about trying to put your kid against bars, inside a moat, in the leopard cage for a photo- op?

How about using the escape of a tapir in the children's zoo to make a SECOND attempt, the first having been firmly refused, to put your kid in the chimp cage?

Two of infinitely many. PEOPLE are the problem, usually.

mscriver said...

When I was a little kid (about the end of WWII), I was by the Portland OR zoo lion cage, which had bars only -- no mesh or glass -- and saw that the lion was asleep with his paw thrust out through the bars about a foot. So I gave it a nice friendly stroke. Lion was both startled and offended! Attacked by a little girl! I used to shake hands with the monkeys, too.

But then the polar bear reached through its bars, grabbed a friendly little boy, and crushed him against the bars -- got him flat enough to pull him through, in pieces. Mostly.

Some heavy thinking on the part of the zoo, and the bars were augmented with mesh. But I still remember the feel of that lion.

At the Lincoln Park Zoo in Chicago (grown up), I used to spend hours in the "cat house." They loved it when the little kids would run pellmell across the wide concrete floor -- their eyes followed every move, they crouched, their tails switched -- esp. on the days the keepers didn't feed them, fasting days to keep them healthy.

Prairie Mary

Camera Trap Codger said...

Steve and Prairie Mary,
Couldn't agree more. Zoo visitors seem to leave their brains at the entrance gate. A retired curator once told me he found a keeper throwing peanuts at a cringing tearful kid in the monkey house. When he asked what was going on the keeper said he was teaching the boy what it like when somebody throws peanuts at you.