When the East Coast was jolted by its largest earthquake in more than a half century on Tuesday, no scientists saw it coming.
But did the vampire bats of the Philadelphia Zoo sense its imminent arrival?
Zoo officials think so.
Like clockwork, the zoo's colony of 20 vampire bats drops from dark perches every day at 11:30 a.m. for a public feeding in the small mammal house.
The scheduled feeding - of blood, what else? - is a popular activity for visitors who get to see the normally nocturnal creatures up close in the darkened exhibit.
On Tuesday none came, puzzling their keepers who thought it must have been a batch of bad blood. [They eat blood from Penn State cows we are told.]
"They were all huddled in the ceiling and we thought, 'what's wrong with them?'" said Christine Bartos, curator ungulates (hoofed mammals) and small mammals. "They never don't come down. We thought something was wrong with the blood."
But that night, after the quake, they came down and ate as usual.
Baros attributes the behavior to the bats' extreme sensitivity. The other zoo animals went about their routines as normal; the tiny bats clearly sensed something was amiss.
No other keepers reported anything unusual that day as the zoo prepared for the debut Wednesday of its new jaguar cub. 
Meanwhile, in Washington D.C. keepers at the National Zoo, which is 140 miles closer to the quake's epicenter, reported many changes in animal behavior before and after the temblor.
Animals let out distress calls, huddled together, stopped eating and climbed trees. A mother gorilla shrieked, grabbed her baby and climbed to the top of a tree. 
Among the other observations:

Red-ruffed lemurs sounded an alarm call about 15 minutes before the quake and then again just after it occurred.

The howler monkeys sounded an alarm call just after the earthquake.

The black and rufous giant elephant-shrew hid in his habitat and refused to come out for afternoon feeding.

The Zoo has a flock of 64 flamingos. Just before the quake, the birds rushed about and grouped themselves together. They remained huddled during the quake.

The report ends on this note:
According to keepers, the giant pandas did not appear to respond to the earthquake.