Zoo mystery: How did apes and birds know quake was coming?

Zoo mystery: How did apes and birds know quake was coming? - The Washington Post:

The zoo documented a broad range of animal behavior before, during and after the tremor that began in central Virginia and shook much of the eastern United States. For example, a gorilla, Mandara, shrieked and grabbed her baby, Kibibi, racing to the top of a climbing structure just seconds before the ground began to shake dramatically. Two other apes — an orangutan, Kyle, and a gorilla, Kojo — already had dropped their food and skedaddled to higher turf.