Scientists have long wondered whether propeller and engine noises from big ships stress whales out. Now, thanks to a poop-sniffing dog and an accidental experiment born of a national tragedy, they may finally have their answer.

Baleen whales use low-frequency sounds to communicate in the ocean. "They're in an environment where there's not a lot of light; they're underwater. They can't rely on eyesight like we do," says veterinarian Roz Rolland of the New England Aquarium in Boston. Some studies have found that whales alter their behavior and vocalizations when noise increases, and it stands to reason, she says, that noise pollution would hinder their ability to communicate and cause them stress. But because scientists can't control the amount of noise in the sea, that's been very hard to prove.

Researchers couldn't stop traffic, but the September 2001 terrorist attacks did. At the time, Rolland was collecting feces of right whales in the Bay of Fundy in Canada so she could try to develop pregnancy tests and other ways to study the animals' reproduction. Animals break up their hormones and get rid of the leftovers in their poop, so feces can show whether an animal is pregnant and reveal its levels of stress. Blood samples would do the same, but feces are much easier to collect.

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