托福听力

🎧 听力原文

Listen to part of a lecture in a biology class. The professor is discussing the behavior of a particular species of bird. Professor: Today we're going to talk about the rufous hummingbird, a small bird known for its remarkable migration. Every year, these birds travel from their wintering grounds in Mexico to their breeding grounds in the western United States and Canada. What's fascinating is the route they take. Instead of flying directly north along the coast, they follow a path through the Rocky Mountains, where they rely on wildflowers for nectar. This timing is critical. The birds must arrive when the flowers are in bloom, but climate change is altering that timing. Warmer springs cause flowers to bloom earlier, sometimes before the birds arrive. As a result, the birds may face a food shortage. In recent years, researchers have observed that some rufous hummingbirds are arriving at their breeding grounds earlier than in the past, but it's unclear whether they can adjust quickly enough. This mismatch between bird arrival and flower blooming is a growing concern for conservationists.