Jane Goodall's work in 1960 showed that ________ were not the only ones to make tools. Since then, scientists have observed different kinds of animals making tools. New Caledonian crows, for example, make tools in order to retrieve the 9. ________ that they eat in the wild. Scientists believe that generally these birds 10. ________ how to make tools. In 2002, a captive New Caledonian crow named Betty invented a new tool. Scientists observed Betty use pieces of wire to make 11. ________ which she used to retrieve food. The interesting thing is that other crows did not 12. ________ the tools. Once the scientists saw Betty make a tool, they tried to get her to 13. ________ the behavior, which she did successfully.
— Crows harassed researchers because they had worn the mask when handling crows (perceived as a threat). the intelligence of corvids ielts reading answers
An inclination or natural tendency to behave in a particular way. Jane Goodall's work in 1960 showed that ________