Read this now: Libya migrant deaths | Italy's Uber protests | Defaced Washington monuments | Mayo Clinic studies motivations to exercise

Here are some of the key stories CNBC is following this hour:

Libya says the bodies of 74 migrants washed ashore in a city on the Mediterranean Sea. The circumstances involving the drowning of the migrants are not yet clear. Migrant deaths have risen to record levels along the Libya-Italy smuggling route.

Italy's taxi drivers staged a sixth day of protests in major cities Tuesday. Demonstrators blocked traffic in central Rome as they pushed the government to crack down on Uber and limousine drivers. Scuffles erupted outside Democratic party headquarters.

Three national monuments in Washington were defaced with graffiti over President's Day weekend, the third major vandalism of memorials in the capital since 2013. The Lincoln Memorial, Washington Monument, and World War II Memorial were hit sometime between Sunday night and Monday morning.

A Mayo Clinic survey reveals that men and women have different motivations for exercising. It found that women exercise to lose weight while men exercise as a form of recreation. But fewer than half knew what their target heart rate should be.