Mandara seemed to know something big was about to happen. So she let out a yell, caught hold of her 2-year-old daughter Kibibi and climbed up into a tree. She lives at the National Zoo in Washington, D.C. And on Tuesday, August 23rd, witnesses say she seemed to sense the big earthquake that shook much of the East Coast before any humans knew what was going on. And she's not the only one. In the moments before the quake, an orangutan   let out a loud call and then climbed to the top of her shelter. "It's very different from their normal call," said Brandie Smith, the zookeeper. "The lemurs (monkey-like animals of Madagascar) will sound an alarm call if they see or hear something highly unusual." But you can't see or hear an earthquake 15 minutes before it happens, can you? Maybe you can -- if you're an animal. "Animals can hear above and below our range of hearing," said Brandie Smith. "That's part of their special abilities. They're more sensitive to the environment, which is how they survive." Primates weren't the only animals that seemed to sense the quake before it happened. One of the elephants made a warning sound. And a huge lizard   ran quickly for _ . The flamingoes (a kind of bird) gathered before the quake and stayed together until the shaking stopped. So what kind of vibrations were the animals picking up in the moments before the quake? Scientist Susan Hough says earthquakes produce two types of waves -- a weak "P" wave and then a much stronger "S" wave. The "P" stands for "primary". And the "S" stands for "secondary". She said she thinks the "P" wave might be what set the animals off. Not all the animals behaved unusually before the quake. For example, Smith says the zoo's giant pandas didn't jump up until the shaking actually began. But many of the other animals seemed to know something was coming before it happened. "I'm not surprised at all," Smith said. Why did Mandara act strangely one day?
Because it sensed something unusual would happen. Because its daughter Kibibi was injured. Because it heard an orangutan let out a loud call. Because an earthquake had happened.