A、Some of them are living in the wild in Hawaii. B、None of them live in the wild. C、They are the most valuable species of crows.

Hello, everybody. Today, I am going to talk about birds using tools.
Scientists have long known that a crow native to New Caledonia is able to use tools. The birds use them to remove food from deep inside holes and crevices. Now, American researchers have discovered a second species of crow that uses tools. Researchers with the San Diego Zoo reported on their experiments with Alala crows—a species from the Hawaiian Islands. There are no more Alala crows living in the wild. But there are some of the birds still living in a protected area in Hawaii. They are considered critically endangered. In an experiment, the researchers placed pieces of food in crevices inside a big piece of wood. The holes are too deep for the birds to reach with their beaks. But, by using small pieces of wood held in their beaks, the birds quickly found a way to get the food. The scientists said the crows demonstrated the ability to reach food in those cannot-reach-it places. The birds used small objects as tools, sometimes changing them by shortening a too-long stick. They also made tools from plant material. "Current evidence strongly suggests that tool use is part of the species’ natural behavioural pattern" , Rutz said.
   Alalas are not the only intelligent crows to use tools. The other is the New Caledonian crow on New Caledonia Island in the Pacific Ocean. The New Caledonian crow can use tools to remove insects and other food from dead wood and plants.
   How did crows learn to use tools? How did these birds learn to use tools? Scientists think their tool-using skills may have resulted, in part, from conditions in their Pacific island habitat. The two species have one more thing in common: unusually straight beaks. The birds use their beaks like the way people use thumbs on their hands.
   All the Alala crows left in the world live in Hawaii. There were less than 20 Alalas left in the late 1990s when scientists decided to bring them into a protected area to increase their population. Now, there are over 100 birds living in captivity. The San Diego Zoo said its researchers tested almost all of them and "they determined that the vast majority of them spontaneously used tools. " Scientists are working to increase the population so that the Alala can be released back into the wild. They plan to release some of the birds back into the wild later this year.
Questions 23 to 25 are based on the recording you have just heard.
23. What does the speaker say about Alala crows?
24. What does Rutz say about the tool use of Alala crows?
25. What can we learn about the two species of crows?