A bird called hermit warbler breeds（繁殖）along the U.S.West Coast. They all kind of look the same and they have a cute little yellow head and a gray body. Typically, birds sing the same one song within one region because the song attracts mates. And different regions can have slightly different dialects of the song. But recently biologists noticed that there are some places that are exceptions to this rule-in some places, there is more than one song in the same place. “So we were curious why that would be the case.” Brett Furnas, a bio-statistician at the California Department of Fish and Wildlife said.

To investigate, Furnas and his team recorded lots of hermit warbler’s songs. In 10 years, they went to 100 different locations throughout the state and all the different potential habitats of the species. The researchers analyzed all the hermit warbler songs they collected and discovered that the hermit warbler doesn’t just break the usual one-song-per-region rule-they positively demolish it, for the researchers found, actually, an amazing 35 different dialects across the state.

But why would the bird repeatedly “alter its song” when any changes could affect its ability to attract a mate? Basically, hermit warblers are very sensitive to fire in the short term, so they will abandon an area temporarily, even if it’s just a low-severity fire that doesn’t destroy the whole stand. And then other hermit warblers singing different dialects move into this area. And then they end up, maybe a few years later, with two or more different dialects in the same place.

Furnas says that such musical diversity might actually work in the hermit warblers’ favor. “They may have greater resiliency（恢复力）to things like climate change. So understanding that helps us to make better conservation decisions to protect biodiversity. But it’s also what makes the outdoors interesting and a beautiful place to be, because even though you might not know it’s a hermit warbler, your experience outdoors is enriched by that diversity.”

【小题1】What is the purpose of Furnas’ research on hermit warbler?

A．To figure out how the bird breeds.

B．To study the one-song-per-region rule.

C．To find why its songs differ within one region.

D．To investigate different habitats of the bird.

【小题2】What does “demolish” in paragraph 2 probably mean?

A．To show the rule is wrong.

B．To prove the rule to be true.

C．To explain what the rule means.

D．To make the rule difficult to understand.

【小题3】Why does hermit warbler frequently have its song “changed”?

A．Because of the food shortage.

B．Because of the less-severe wildfire.

C．Because of the need to attract a mate.

D．Because of the competition for habitats.

【小题4】What does the last paragraph talk about?

A．The effect climate change has on birds.

B．The importance of biodiversity protection.

C．The ways to enrich your outdoor experience.

D．The significance of the musical diversity of hermit warbler.