การฟัง TOEFL

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Listen to part of a lecture in a biology class. The professor is discussing the behavior of a specific type of bird, the cuckoo. Professor: Today, let's talk about brood parasitism, a fascinating reproductive strategy. The common cuckoo, for instance, doesn't build its own nest. Instead, the female lays her eggs in the nests of other bird species, like the reed warbler. Now, you might wonder, why doesn't the host bird reject the foreign egg? Well, research shows that the cuckoo egg often mimics the host's eggs in color and pattern, making it difficult to detect. But there's more. The cuckoo chick, once hatched, has a special behavior: it pushes the host's eggs and chicks out of the nest. This ensures the host parents focus all their attention on feeding the cuckoo, which grows much larger than its foster parents. Interestingly, some host species have evolved defenses, like recognizing and removing foreign eggs. This leads to an evolutionary arms race between the cuckoo and its hosts.