Read the Passage

Monarchs on the Move Each autumn, many monarch butterflies travel south from the United States and Canada to wintering sites in Mexico. Some travel more than 2,000 miles. The butterflies that arrive in Mexico have not made the journey before, yet they follow a route that has been passed down through generations. Monarchs use more than one clue to find their way. They can sense the position of the sun and adjust their direction as the day passes. Scientists also study how an internal compass helps the butterflies orient themselves. Winds can carry monarchs along, allowing them to cover long distances while using less energy. The monarch migration faces serious challenges. The loss of milkweed and other plants leaves fewer places for monarchs to lay eggs and find food. Pesticides can harm butterflies, and changing weather can disrupt their journey. People are working to help by protecting habitats and planting milkweed.