From the study:
"Using simple physics, we have shown a highly possible solution as to how the tiger was able to escape its enclosure. From our calculations it was shown that a tiger only needs a little over 26 miles per hour to cross the 33 ft moat and clear the 12.5 ft high wall. From the current data that is available, a tiger can attain a maximum speed of 35 miles per hour. Hence, the current dimensions of the enclosure are not enough to ensure that a tiger will not escape."A good analysis of the researchers' findings is at Greg Laden's Blog. After discussing some problems he has with the findings, he concludes:
I have no problem believing that this is physically possible. This is for two reasons. One, I've seen some pretty amazing leaping in cats, including large cats, and I suspect the range of jumping capacities of the large cats is unmeasured but impressive. Two, it actually happened, so in my own naive way I assume it was possible.Based on these calculations, it is obvious that the zoo enclosure must be higher. But the question remains: why did the tiger never try to escape before this event?