Definition: In this task, you're given an article and an answer. Your task is to generate the fill-in-the-blank question for this answer based on the given article. The blanks are always at the end of the question, and can be filled with more than one word or phrase.
Input: Article: Passage 1 Does the early bird catch the worm? No, he saves it for tea: Animals seek out food in the morning but don't tuck in until afternoon. The early bird,strategy was revealed in an experiment in which over 2,000 birds were fitted with tiny radio tags which activated when they landed on feeders hidden in the woods. The feeders were moved around over the course of the day and the researchers noted when the birds landed on them. This revealed that the birds were much better at finding the feeders' new locations in the morning. However, they waited until the afternoon to get tucked in. The researchers said the complex strategy acts as an insurance policy, with birds remaining light yet still able to get enough fat to survive the night. It is particularly important in winter when the risks of predation are high and just one day without food can make the difference between life and death for small birds. Passage 2 What is a place where you could find old pictures of camels carrying people to Mecca, Saudi Arabia, and also books about ancient Aztecs in Mexico? It is all found in the World Digital Library (WDL). Its collection is available on the Internet. The library has 8,000 items from whole books to ancient writings, to music and photographs. James Billington, who launched the WDL in 2009, says he wanted it to include items that are both interesting and important. Every item is explained in the 6 official languages of the United Nations: English, Arabic, French, Spanish, Chinese, Russian plus Portuguese. 25 million people have visited the website from 250 places since. Anyone may search the World Digital Library by subject, time period, kind of document or area of the world. The website is www.wdl.org.
Answer: hunters who hide themselves in the woods
Output:
According to Passage 1, we can know feeders are _ .