I want to test the ability of students to read a passage and answer questions about it. Could you please come up with a good question for the passage "Within a population, it is common for different ages and/or sexes to have different patterns of timing and distance. Female chaffinches Fringilla coelebs in Eastern Fennoscandia migrate earlier in the autumn than males do."? 

Countries that are located in a region opposite to the Western side of said region are given which descriptor?